Maternal Mosaicism

Inheritance mosaicism2

This new article by Emma Bedoukian and collegues present the first report of germline inheritance of Bohring-Opitz Syndrome.
“[…] Most patients [affected with Bohring-Opitz Syndrome (BOS)] […] have a de novo nonsense or frameshift variant in ASXL1. We report a case of BOS caused by a pathogenic ASXL1 variant inherited from a germline mosaic mother. The ASXL1 mutation was detected via trio exome sequencing. The sequencing data demonstrated that the variant was inherited maternally but that the maternal variant was underrepresented in comparison to the normal allele. These results suggested maternal mosaicism for the variant. Additional testing on the mother was performed on buccal cell DNA, which was also consistent with mosaicism. The mother had been reported to be healthy and the family history is unremarkable. This is the first report of BOS caused by a mutation inherited from an unaffected, presumed germline mosaic parent. This phenomenon has been reported for other traditionally de novo dominant disorders like CHARGE syndrome and Cornelia de Lange syndrome. This case emphasizes the need for accurate low but non‐negative recurrence risk counseling for families with children with BOS and it impacts exome interpretation strategy.”

» Bedoukian E, Copenheaver D, Bale S, Deardorff M. Bohring‐Opitz syndrome caused by an ASXL1 mutation inherited from a germline mosaic mother. Am J Med Genet Part A. 2018;176A:1249–1252. https://doi.org/10.1002/ajmg.a.38686

Inheritance mosaicism1

In most of the cases Bohring-Opitz syndrome (BOS) is the result of a novo mutation in the  ASXL1 gene. The risk of having another child with Bohring-Opitz Syndrome is low. (Russell, B. et al. 2018)

Inheritance de novo

»Read also our blog post https://bohring-opitz.org/2017/10/30/bos-inherited-by-germline-mosaicism/

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