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<!-- Creation Date      : 2021-03-25T17:09:15.2924499+00:00 -->
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<!-- Copyright (c) 2021 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
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  <xsd:element id="fdmt_AccruedAndOtherCurrentLiabilities" name="AccruedAndOtherCurrentLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_ResearchAndDevelopmentExpenseRelatedParty" name="ResearchAndDevelopmentExpenseRelatedParty" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues" name="TemporaryEquityStockIssuedDuringPeriodSharesNewIssues" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_TemporaryEquityStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" name="TemporaryEquityStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_TemporaryEquityStockIssuedDuringPeriodValueConversionOfConvertibleSecurities" name="TemporaryEquityStockIssuedDuringPeriodValueConversionOfConvertibleSecurities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_AdjustmentsToAdditionalPaidInCapitalVestingOfStockWarrantIssuedForServices" name="AdjustmentsToAdditionalPaidInCapitalVestingOfStockWarrantIssuedForServices" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_TemporaryEquityIssuanceCost" name="TemporaryEquityIssuanceCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_VestingOfCommonStockWarrantInReturnForServices" name="VestingOfCommonStockWarrantInReturnForServices" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_WriteOffOfPublicOfferingCosts" name="WriteOffOfPublicOfferingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_UnpaidOfferingCosts" name="UnpaidOfferingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_AccruedAndOtherLiabilitiesTextBlock" name="AccruedAndOtherLiabilitiesTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ResearchAndCollaborationArrangementsAbstract" name="ResearchAndCollaborationArrangementsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_LicenseArrangementsTextBlock" name="LicenseArrangementsTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_LicenseArrangementsAbstract" name="LicenseArrangementsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_TemporaryEquityDisclosureTextBlock" name="TemporaryEquityDisclosureTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CommonStockWarrantsTextBlock" name="CommonStockWarrantsTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_OtherRisksAndUncertaintiesPolicyPolicyTextBlock" name="OtherRisksAndUncertaintiesPolicyPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_RedeemableConvertiblePreferredStockPolicyPolicyTextBlock" name="RedeemableConvertiblePreferredStockPolicyPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CommonStockWarrantsPolicyPolicyTextBlock" name="CommonStockWarrantsPolicyPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_AccruedResearchAndDevelopmentPolicyPolicyTextBlock" name="AccruedResearchAndDevelopmentPolicyPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_DeferredOfferingCostsPolicyPolicyTextBlock" name="DeferredOfferingCostsPolicyPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ScheduleOfCollaborationAndLicenseRevenueTableTextBlock" name="ScheduleOfCollaborationAndLicenseRevenueTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ScheduleOfCommonShareReservedForFutureIssuance" name="ScheduleOfCommonShareReservedForFutureIssuance" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CommonStockSharesIssuedUponUnderwritersExerciseOfOverallotmentOption" name="CommonStockSharesIssuedUponUnderwritersExerciseOfOverallotmentOption" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_OrganizationAndNatureOfBusinessLineItems" name="OrganizationAndNatureOfBusinessLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_OrganizationAndNatureOfBusinessTable" name="OrganizationAndNatureOfBusinessTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_SummaryOfSignificantAccountingPoliciesLineItems" name="SummaryOfSignificantAccountingPoliciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_SummaryOfSignificantAccountingPoliciesTable" name="SummaryOfSignificantAccountingPoliciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_DeferredRevenueMember" name="DeferredRevenueMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_NumberOfFinancialInstitutionsWhereCashIsHeld" name="NumberOfFinancialInstitutionsWhereCashIsHeld" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CustomerAMember" name="CustomerAMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_CustomerBMember" name="CustomerBMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_AccruedClinicalAndPreclinicalStudyCosts" name="AccruedClinicalAndPreclinicalStudyCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_CollaborationAndLicenseRevenueMember" name="CollaborationAndLicenseRevenueMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_UniQureBiopharmaBVMember" name="UniQureBiopharmaBVMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_BenitecBiopharmaLimitedMember" name="BenitecBiopharmaLimitedMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_ChoroideremiaResearchFoundationMember" name="ChoroideremiaResearchFoundationMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_FHoffmannLaRocheLtdAndHoffmannLaRocheIncMember" name="FHoffmannLaRocheLtdAndHoffmannLaRocheIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_CysticFibrosisFoundationMember" name="CysticFibrosisFoundationMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_AstraZenecaMember" name="AstraZenecaMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_UniQureAgreementMember" name="UniQureAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_AmendedUniQureAgreementMember" name="AmendedUniQureAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_CollaborativeArrangementInitialResearchTerm" name="CollaborativeArrangementInitialResearchTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_UpfrontPaymentReceived" name="UpfrontPaymentReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_CollaborativeArrangementResearchAndDevelopmentMilestonesEntitledToReceiveForEachLicensedProduct" name="CollaborativeArrangementResearchAndDevelopmentMilestonesEntitledToReceiveForEachLicensedProduct" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_OptionsToPurchaseOrdinaryShares" name="OptionsToPurchaseOrdinaryShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_VestingPeriodOfShareAwards" name="VestingPeriodOfShareAwards" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_FairValueOfOptions" name="FairValueOfOptions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_FairValueOfNonMonetaryConsiderationOfIntellectualPropertyRights" name="FairValueOfNonMonetaryConsiderationOfIntellectualPropertyRights" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_NumberOfProjectVariants" name="NumberOfProjectVariants" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="fdmt_BenitecAgreementMember" name="BenitecAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_CollaborativeArrangementExtendedIncrementsTerm" name="CollaborativeArrangementExtendedIncrementsTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CollaborativeArrangementAdditionalResearchTerm" name="CollaborativeArrangementAdditionalResearchTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ConsiderationReceivedUponAmendmentOfAgreement" name="ConsiderationReceivedUponAmendmentOfAgreement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_DeferredRevenueRecognizedAsUpfrontPayment" name="DeferredRevenueRecognizedAsUpfrontPayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_CollaborativeArrangementReimbursementsForCostsIncurred" name="CollaborativeArrangementReimbursementsForCostsIncurred" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_ChangeInCollaborativeArrangementTransactionPrice" name="ChangeInCollaborativeArrangementTransactionPrice" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_CollaborativeArrangementContributionUponDevelopmentMilestone" name="CollaborativeArrangementContributionUponDevelopmentMilestone" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_ChoroideremiaResearchFoundationAgreementMember" name="ChoroideremiaResearchFoundationAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_MaximumContingentPaymentUponExerciseOfOptionToConvertAProduct" name="MaximumContingentPaymentUponExerciseOfOptionToConvertAProduct" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_DevelopmentMilestonePayments" name="DevelopmentMilestonePayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_DevelopmentMilestonePaymentsRelatingToChoroideremia" name="DevelopmentMilestonePaymentsRelatingToChoroideremia" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_CollaborativeArrangementSalesBasedMilestonePayments" name="CollaborativeArrangementSalesBasedMilestonePayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_ContingentPaymentForEachNominatedProductBeyondFirstThree" name="ContingentPaymentForEachNominatedProductBeyondFirstThree" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_TwoThousandAndSeventeenRocheAgreementMember" name="TwoThousandAndSeventeenRocheAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_CollaborationArrangementsEstimatedReimbursementsForResearchAndDevelopmentServices" name="CollaborationArrangementsEstimatedReimbursementsForResearchAndDevelopmentServices" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_CollaborativeArrangementAdjustmentToTransactionPrice" name="CollaborativeArrangementAdjustmentToTransactionPrice" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_CollaborativeArrangementIncreaseOfProjectScopeAndExpectedReimbursableCosts" name="CollaborativeArrangementIncreaseOfProjectScopeAndExpectedReimbursableCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_CollaborativeArrangementAdditionOfVariableConsideration" name="CollaborativeArrangementAdditionOfVariableConsideration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_IncreaseDecreaseInContractWithCustomerRevenueRecognized" name="IncreaseDecreaseInContractWithCustomerRevenueRecognized" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_CollaborativeArrangementAchievedMilestones" name="CollaborativeArrangementAchievedMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_ExpectedPaymentsPercentageToEqualActualAwardReceived" name="ExpectedPaymentsPercentageToEqualActualAwardReceived" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_NumberOfInstallmentsToPayActualAward" name="NumberOfInstallmentsToPayActualAward" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ActualAwardPaymentPeriodUponFirstCommercialSaleOfProduct" name="ActualAwardPaymentPeriodUponFirstCommercialSaleOfProduct" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CollaborativeArrangementsFutureSalesBasedMilestonePaymentsPercentage" name="CollaborativeArrangementsFutureSalesBasedMilestonePaymentsPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CollaborativeArrangementsRoyaltiesPercentageOnActualAwardReceived" name="CollaborativeArrangementsRoyaltiesPercentageOnActualAwardReceived" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ContinuousPeriodWhereCompanyCeasesToDevelopOrCommercializeAnyProduct" name="ContinuousPeriodWhereCompanyCeasesToDevelopOrCommercializeAnyProduct" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CollaborativeArrangementTransactionPriceAdjustment" name="CollaborativeArrangementTransactionPriceAdjustment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_NumberOfProjectsVectorVariantsGrantedOptionToLicenseToDevelopmentAndCommercialization" name="NumberOfProjectsVectorVariantsGrantedOptionToLicenseToDevelopmentAndCommercialization" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CollaborativeArrangementExtendAdditionalResearchTerm" name="CollaborativeArrangementExtendAdditionalResearchTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CollaborativeArrangementProjectsExpiresOnConclusionOfResearchPhase" name="CollaborativeArrangementProjectsExpiresOnConclusionOfResearchPhase" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_NonRefundableLicenseFeePayableUponExecution" name="NonRefundableLicenseFeePayableUponExecution" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_AmountObligatedToPayUponClosingFirstQualifiedFinancingAtOption" name="AmountObligatedToPayUponClosingFirstQualifiedFinancingAtOption" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_PercentageOfEquityInterestUponClosingFirstQualifiedFinancingAtOption" name="PercentageOfEquityInterestUponClosingFirstQualifiedFinancingAtOption" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_NonRefundableLicenseFeePayableEveryYearAfterExecution" name="NonRefundableLicenseFeePayableEveryYearAfterExecution" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_PercentageOfEquityInterestsIssuedAsCommonStock" name="PercentageOfEquityInterestsIssuedAsCommonStock" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_UCAgreementsMember" name="UCAgreementsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_AmountObligatedToPayNonRefundableLicenseFeeAnnually" name="AmountObligatedToPayNonRefundableLicenseFeeAnnually" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_AmountPaidNonRefundableLicenseFee" name="AmountPaidNonRefundableLicenseFee" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_AnnualRoyalty" name="AnnualRoyalty" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_DevelopmentMilestones" name="DevelopmentMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_IncurredExpenses" name="IncurredExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_TenantLeaseImprovementAllowance" name="TenantLeaseImprovementAllowance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_OperatingLeaseTermExtendedExpirationPeriod" name="OperatingLeaseTermExtendedExpirationPeriod" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_CommitmentAndContingenciesLineItems" name="CommitmentAndContingenciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_CommitmentAndContingenciesTable" name="CommitmentAndContingenciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_AccruedAndOtherCurrentLiabilitiesMember" name="AccruedAndOtherCurrentLiabilitiesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_PercentageOfAnnualRentEscalations" name="PercentageOfAnnualRentEscalations" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_OperatingLossCarryforwardsExpirationYear" name="OperatingLossCarryforwardsExpirationYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_TaxCreditCarryforwardExpirationDescription" name="TaxCreditCarryforwardExpirationDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_TaxCreditCarryforwardBeginningExpirationYear" name="TaxCreditCarryforwardBeginningExpirationYear" type="us-types:gYearListItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_NetOperatingLossCarryforwardsExpectedToExpireUnutilized" name="NetOperatingLossCarryforwardsExpectedToExpireUnutilized" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_CARESActReliefDescription" name="CARESActReliefDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_SeriesCRedeemableConvertiblePreferredStockMember" name="SeriesCRedeemableConvertiblePreferredStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_SeriesBRedeemableConvertiblePreferredStockMember" name="SeriesBRedeemableConvertiblePreferredStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_FundingAgreementProductMember" name="FundingAgreementProductMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_SeriesARedeemableConvertiblePreferredStockMember" name="SeriesARedeemableConvertiblePreferredStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_SeriesA1RedeemableConvertiblePreferredStockMember" name="SeriesA1RedeemableConvertiblePreferredStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_MinimumGrossProceedsFromIPOForAutomaticConversionToCommonStock" name="MinimumGrossProceedsFromIPOForAutomaticConversionToCommonStock" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_AdditionalFundingCommitted" name="AdditionalFundingCommitted" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="fdmt_FounderMember" name="FounderMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_TwoThousandFifteenEquityIncentivePlanMember" name="TwoThousandFifteenEquityIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_TwoThousandTwentyEquityIncentivePlanMember" name="TwoThousandTwentyEquityIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_TwoThousandTwentyIncentiveAwardPlanMember" name="TwoThousandTwentyIncentiveAwardPlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_TwoThousandTwentyEmployeeStockPurchasePlanMember" name="TwoThousandTwentyEmployeeStockPurchasePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_EmployeeMember" name="EmployeeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_NonemployeeMember" name="NonemployeeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_MinimumPercentageOfOutstandingSharesHeldByIndividual" name="MinimumPercentageOfOutstandingSharesHeldByIndividual" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceAsPercentageOfFairMarketValueMinimum" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceAsPercentageOfFairMarketValueMinimum" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_EmployeePurchasePriceOfCommonStockAsPercentageOfFairMarketValue" name="EmployeePurchasePriceOfCommonStockAsPercentageOfFairMarketValue" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockOverlappingOfferingPeriod" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardStockOverlappingOfferingPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ShareBasedCompensationArrangementByShareBasedPaymentAwardDurationPurchasePeriod" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardDurationPurchasePeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesAvailableForGrantGrantsInPeriodGross" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesAvailableForGrantGrantsInPeriodGross" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesAvailableForGrantExpirationsInPeriod" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesAvailableForGrantExpirationsInPeriod" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesAvailableForGrantForfeituresInPeriod" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesAvailableForGrantForfeituresInPeriod" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_NumberOfWarrantsIssued" name="NumberOfWarrantsIssued" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_WarrantExpiresYear" name="WarrantExpiresYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_SeriesBFinancingMember" name="SeriesBFinancingMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_WarrantVestsOverPeriod" name="WarrantVestsOverPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_FairValueAssumptionsChangeOfControlPayment" name="FairValueAssumptionsChangeOfControlPayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="fdmt_FairValueAssumptionsProbabilityOfChangeInControlEventPercentage" name="FairValueAssumptionsProbabilityOfChangeInControlEventPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_FairValueAssumptionsProbabilityOfChangeInControlDiscountRate" name="FairValueAssumptionsProbabilityOfChangeInControlDiscountRate" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_PfizerMember" name="PfizerMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_CoFounderAndChiefScientificAdvisorMember" name="CoFounderAndChiefScientificAdvisorMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_UCRegentsMember" name="UCRegentsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_ConsultingServicesMember" name="ConsultingServicesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_SponsoredResearchAgreementsMember" name="SponsoredResearchAgreementsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_IgniteMember" name="IgniteMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="fdmt_ConvertiblePreferredStockNumberOfSharesConverted" name="ConvertiblePreferredStockNumberOfSharesConverted" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="fdmt_NumberOfAgreementsEntered" name="NumberOfAgreementsEntered" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_TermOfAgreement" name="TermOfAgreement" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="fdmt_TwoThousandFourteenPlanMember" name="TwoThousandFourteenPlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
</xsd:schema>
