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  <xsd:element id="ptct_EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017TransitionTaxOnAccumulatedForeignEarningsPercent" name="EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017TransitionTaxOnAccumulatedForeignEarningsPercent" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_EmflazaMember" name="EmflazaMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_EmployeeStockPurchasePlanVotingPercentageLimitPercent" name="EmployeeStockPurchasePlanVotingPercentageLimitPercent" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_Equity2009AndLongTermIncentivePlanAndStockIncentivePlan2013Member" name="Equity2009AndLongTermIncentivePlanAndStockIncentivePlan2013Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_EquityAndLongTermIncentivePlan2009Member" name="EquityAndLongTermIncentivePlan2009Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_FairValueAssetsTransfersBetweenLevel1AndLevel2Amount" name="FairValueAssetsTransfersBetweenLevel1AndLevel2Amount" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="ptct_FiniteLivedIntangibleAssetsAmortizationExpenseYearFiveAndThereafter" name="FiniteLivedIntangibleAssetsAmortizationExpenseYearFiveAndThereafter" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="ptct_FirstFiveYearsMember" name="FirstFiveYearsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_FurnitureFixturesAndLabEquipmentMember" name="FurnitureFixturesAndLabEquipmentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_InducementGrantPlanMember" name="InducementGrantPlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_InventoriesAndCostOfProductSalesPolicyTextBlock" name="InventoriesAndCostOfProductSalesPolicyTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_LineOfCreditFacilityAdditionalCapacityAvailable" name="LineOfCreditFacilityAdditionalCapacityAvailable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="ptct_LineOfCreditFacilityNetProductRevenueThresholdAdditionalCapacity" name="LineOfCreditFacilityNetProductRevenueThresholdAdditionalCapacity" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="ptct_LineOfCreditFacilityNetProductRevenueThresholdAdditionalCapacityTrailingPeriod" name="LineOfCreditFacilityNetProductRevenueThresholdAdditionalCapacityTrailingPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_LongTermIncentivePlan2013Member" name="LongTermIncentivePlan2013Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_MarathonPharmaceuticalsLLCMember" name="MarathonPharmaceuticalsLLCMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_MidCapFinancialTrustMember" name="MidCapFinancialTrustMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_MilestoneAxis" name="MilestoneAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_MilestoneDomain" name="MilestoneDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_MinimumAgeOfAmbulatoryPatient" name="MinimumAgeOfAmbulatoryPatient" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_MinimumPercentageOfDebtPrincipalAmountByInstrumentHolders" name="MinimumPercentageOfDebtPrincipalAmountByInstrumentHolders" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_NetDeferredTaxLiabilitiesConvertibleDebtInstruments" name="NetDeferredTaxLiabilitiesConvertibleDebtInstruments" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="ptct_NumberOfCountries" name="NumberOfCountries" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_OperatingLossCarryforwardsForImmediateUse" name="OperatingLossCarryforwardsForImmediateUse" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="ptct_OperatingLossCarryforwardsInNextTwelveMonths" name="OperatingLossCarryforwardsInNextTwelveMonths" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="ptct_PropertyPlantAndEquipmentUsefulLifeTableTextBlock" name="PropertyPlantAndEquipmentUsefulLifeTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_RenewalOfMarketingAuthorizationPeriod" name="RenewalOfMarketingAuthorizationPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_ResearchAndDevelopmentEventMilestonesMember" name="ResearchAndDevelopmentEventMilestonesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_RocheAndSmaFoundationMember" name="RocheAndSmaFoundationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_SalesAllowanceAndOtherRelatedCosts" name="SalesAllowanceAndOtherRelatedCosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="ptct_SalesMilestonesMember" name="SalesMilestonesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_ScheduleOfInterestExpenseRecognizedRelatedToConvertibleDebtTableTextBlock" name="ScheduleOfInterestExpenseRecognizedRelatedToConvertibleDebtTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_ScheduleOfPurchasePriceTableTextBlock" name="ScheduleOfPurchasePriceTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedAnnualIncreaseAsPercentageOfStockOutstanding" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedAnnualIncreaseAsPercentageOfStockOutstanding" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedAnnualIncreaseNumber" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedAnnualIncreaseNumber" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedSharesSubjectToOutstandingAwards" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedSharesSubjectToOutstandingAwards" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
  <xsd:element id="ptct_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedExercisePriceAsPercentageOfFairMarketValueOfCommonStock" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedExercisePriceAsPercentageOfFairMarketValueOfCommonStock" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="ptct_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedToStockholdersWithSpecifiedOwnershipPercentageExercisePriceAsPercentageOfFairMarketValueOfCommonStock" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedToStockholdersWithSpecifiedOwnershipPercentageExercisePriceAsPercentageOfFairMarketValueOfCommonStock" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="ptct_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePrice" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePrice" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsIntrinsicValueRollForward" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsIntrinsicValueRollForward" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockholdersSpecifiedOwnershipPercentage" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardStockholdersSpecifiedOwnershipPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="ptct_StockAppreciationRightsLiabilityOutstanding" name="StockAppreciationRightsLiabilityOutstanding" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="ptct_StockIncentivePlan2013Member" name="StockIncentivePlan2013Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_TaxCutsAndJobsActOf2017ChangeInTaxRateIncomeTaxExpenseBenefit" name="TaxCutsAndJobsActOf2017ChangeInTaxRateIncomeTaxExpenseBenefit" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="ptct_TermOfGrantProgram" name="TermOfGrantProgram" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_ThereAfterFiveYearsMember" name="ThereAfterFiveYearsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_TranslarnaMember" name="TranslarnaMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="ptct_WarrantLiabilityPolicyTextBlock" name="WarrantLiabilityPolicyTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="ptct_WellcomeTrustLimitedMember" name="WellcomeTrustLimitedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
</xsd:schema>
