title: De novo mtDNA point mutations are common and have a low recurrence risk.
abstract: Severe, disease-causing germline mitochondrial (mt)DNA mutations are maternally inherited or arise de novo. Strategies to prevent transmission are generally available, but depend on recurrence risks, ranging from high/unpredictable for many familial mtDNA point mutations to very low for sporadic, large-scale single mtDNA deletions. Comprehensive data are lacking for de novo mtDNA point mutations, often leading to misconceptions and incorrect counselling regarding recurrence risk and reproductive options. We aim to study the relevance and recurrence risk of apparently de novo mtDNA point mutations.
  
  
  
  Systematic study of prenatal diagnosis (PND) and recurrence of mtDNA point mutations in families with de novo cases, including new and published data. 'De novo' based on the absence of the mutation in multiple (postmitotic) maternal tissues is preferred, but mutations absent in maternal blood only were also included.
  
  
  
  In our series of 105 index patients (33 children and 72 adults) with (likely) pathogenic mtDNA point mutations, the de novo frequency was 24.6%, the majority being paediatric. PND was performed in subsequent pregnancies of mothers of four de novo cases. A fifth mother opted for preimplantation genetic diagnosis because of a coexisting Mendelian genetic disorder. The mtDNA mutation was absent in all four prenatal samples and all 11 oocytes/embryos tested. A literature survey revealed 137 de novo cases, but PND was only performed for 9 (including 1 unpublished) mothers. In one, recurrence occurred in two subsequent pregnancies, presumably due to germline mosaicism.
  
  
  
  De novo mtDNA point mutations are a common cause of mtDNA disease. Recurrence risk is low. This is relevant for genetic counselling, particularly for reproductive options. PND can be offered for reassurance.
authors.affiliation: Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.
authors.forename: Suzanne C E H
authors.initials: SC
authors.lastname: Sallevelt
authors.affiliation: Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.|Research School for Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands.
authors.forename: Christine E M
authors.initials: CE
authors.lastname: de Die-Smulders
authors.affiliation: Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.
authors.forename: Alexandra T M
authors.initials: AT
authors.lastname: Hendrickx
authors.affiliation: Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.
authors.forename: Debby M E I
authors.initials: DM
authors.lastname: Hellebrekers
authors.affiliation: Department of Neurology, Erasmus MC-Sophia Children's Hospital Rotterdam, Rotterdam, The Netherlands.
authors.forename: Irenaeus F M
authors.initials: IF
authors.lastname: de Coo
authors.affiliation: Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Charlotte L
authors.initials: CL
authors.lastname: Alston
authors.affiliation: Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Knowles
authors.affiliation: Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Taylor
authors.affiliation: Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: McFarland
authors.affiliation: Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.|Research School for Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands.|Research School for Cardiovascular Diseases in Maastricht, CARIM, Maastricht University, Maastricht, The Netherlands.
authors.forename: Hubert J M
authors.initials: HJ
authors.lastname: Smeets
mesh_terms: D000328:Adult; D002648:Child; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D005817:Genetic Counseling; D030342:Genetic Diseases, Inborn / Q000175:diagnosis*; D006801:Humans; D008297:Male; D000072741:Maternal Inheritance / Q000235:genetics*; D009865:Oocytes / Q000378:metabolism; D017354:Point Mutation / Q000235:genetics; D011247:Pregnancy; D019836:Preimplantation Diagnosis; D011296:Prenatal Diagnosis
chemical_list: D004272:DNA, Mitochondrial
keywords: de novo; genetic counselling; mDNA mutations; prenatal diagnosis (PND)