Frontiers in Genetics (Dec 2023)

Case report: Complete paternal isodisomy on chromosome 18 induces methylation changes in PARD6G-AS1 promotor in a case with arthrogryposis

  • Johanna Moch,
  • Maximilian Radtke,
  • Janina Gburek-Augustat,
  • Maike Karnstedt,
  • Senta Schönnagel,
  • Stephan H. Drukewitz,
  • Laura Pilgram,
  • Julia Hentschel,
  • Isabell Schumann

DOI
https://doi.org/10.3389/fgene.2023.1297754
Journal volume & issue
Vol. 14

Abstract

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Uniparental disomy (UPD) is the inheritance of both alleles of a chromosome from only one parent. So far, the detection of UPDs in sequencing data is not well established and a known gap in next-generation sequencing (NGS) diagnostics. By developing a new tool for UPD detection, we re-evaluated an eight-year-old individual presenting with scoliosis, muscle weakness and global developmental delay. Previous panel analysis identified a homozygous likely pathogenic loss-of-function variant in the PIEZO2-gene associated with arthrogryposis (OMIM # 617146). Interestingly, during a re-evaluation process, we identified a region of homozygosity (ROH) covering over 95% of chromosome 18. Segregation and microsatellite analysis within the family revealed that only the father is a heterozygous carrier of the variant in PIEZO2 and confirmed paternal uniparental isodisomy (iUPD) on chromosome 18 in the individual. Further methylation analysis indicated demethylation of the promotor region of PARD6G-AS1, which is described to be maternally imprinted and could possibly influence the individuals’ phenotype. Our report describes the first complete iUPD on chromosome 18 and highlights that UPDs can be a cause for homozygous pathogenic variants, which reduces the risk of reoccurrence in case of a new pregnancy in comparison to an autosomal recessive inheritance trait significantly.

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