Clinical and genetic characterization of PYROXD1-related myopathy patients from Turkey


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Daimagueler H., Akpulat U., Oezdemir Ö. , YİŞ U., GÜNGÖR S., TALİM B., ...More

AMERICAN JOURNAL OF MEDICAL GENETICS PART A, vol.185, no.6, pp.1678-1690, 2021 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 185 Issue: 6
  • Publication Date: 2021
  • Doi Number: 10.1002/ajmg.a.62148
  • Title of Journal : AMERICAN JOURNAL OF MEDICAL GENETICS PART A
  • Page Numbers: pp.1678-1690

Abstract

Congenital myopathies (CMs) are a heterogeneous group of inherited muscle disorders characterized by muscle weakness at birth, while limb-girdle muscular dystrophies (LGMD) have a later onset and slower disease progression. Thus, detailed clinical phenotyping of genetically defined disease entities are required for the full understanding of genotype-phenotype correlations. A recently defined myopathic genetic disease entity is caused by bi-allelic variants in a gene coding for pyridine nucleotide-disulfide oxidoreductase domain 1 (PYROXD1) with unknown substrates. Here, we present three patients from two consanguineous Turkish families with mild LGMD, facial weakness, normal CK levels, and slow progress. Genomic analyses revealed a homozygous known pathogenic missense variant (c.464A>G, p.Asn155Ser) in family 1 with two affected females. In the affected male of family 2, we found this variant in a compound heterozygous state together with a novel frameshift variant (c.329_332delTCTG, p.Leu112Valfs*8), which is the second frameshift variant known so far in PYROXD1. We have been able to define a large homozygous region in family 1 sharing a common haplotype with family 2 in the critical region. Our data suggest that c.464A>G is a Turkish founder mutation. To gain deeper insights, we performed a systematic review of all published PYROXD1-related myopathy cases. Our analysis showed that the c.464A > G variant was found in 87% (20/23) of the patients and that it may cause either a childhood- or adult-onset phenotype, irrespective of its presence in a homozygous or compound heterozygous state. Interestingly, only four patients had elevated CK levels (up to 1000 U/L), and cardiac involvement was found in few compound heterozygous cases.