A pathogenic haplotype, common in Europeans, causes autosomal recessive albinism and uncovers missing heritability in OCA1

Karen Grønskov*, Cathrine Jespersgaard, Gitte Hoffmann Bruun, Pernille Harris, Karen Brøndum-Nielsen, Brage S Andresen, Thomas Rosenberg

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Abstrakt

Oculocutaneous albinism (OCA) is a genetically heterogeneous disorder. Six genes are associated with autosomal recessive OCA (TYR, OCA2, TYRP1, SLC45A2, SLC24A5 and LRMDA), and one gene, GPR143, is associated with X-linked ocular albinism (OA). Molecular genetic analysis provides a genetic diagnosis in approximately 60% of individuals with clinical OA/OCA. A considerably number of the remaining 40% are heterozygous for a causative sequence variation in TYR. To identify missing causative sequence variants in these, we used a NGS based approach, genotyping and segregation analysis. We report two putative pathogenic haplotypes which only differ by two extremely rare SNVs, indicating that the haplotypes have a common derivation. Both haplotypes segregate consistent with an autosomal recessive inheritance pattern and include the allele p.S192Y-p.R402Q. An explanation for the pathogenicity of the haplotypes could be the combination of p.S192Y and p.R402Q. Homozygosity for the pathogenic haplotypes causes a partial albinism phenotype. In our cohort, 15% of affected individuals had a molecular genetic diagnosis involving the pathogenic haplotype. Consequently, the prevalence of albinism seems to be substantially underestimated, and children with unexplained bilateral subnormal vision and/or nystagmus should be analysed clinically and molecularly for albinism.

OriginalsprogEngelsk
Artikelnummer645
TidsskriftScientific Reports
Vol/bind9
Udgave nummer1
Antal sider7
ISSN2045-2322
DOI
StatusUdgivet - 24. jan. 2019

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