Dataset Information

Identification and Computational Analysis of Novel TYR and SLC45A2 Gene Mutations in Pakistani Families With Identical Non-syndromic Oculocutaneous Albinism.

ABSTRACT: Non-syndromic oculocutaneous albinism (nsOCA) is an inherited disorder of melanin biosynthesis with autosomal recessive mode of inheritance, presenting either hypopigmented or depigmented skin, hair, and eyes. It is genetically heterogeneous with seven loci (OCA1-OCA7) reported to date. In the present study, we have reported three consanguineous families (A, B, C) presenting identical nsOCA phenotypes. Sanger sequencing revealed a novel [NM_000372.5: c.826 T > C, p.(Cys276Arg)] and a recurrent variant [NM_000372.5: c.832C > T, p.(Arg278^∗)] in tyrosinase (TYR) in families A and B, respectively. Microsatellite marker-based homozygosity mapping linked family C to OCA4. Sequence analysis identified a novel insertion variant (NM_016180.5: c.1331_1332insA) in the SLC45A2. Further, in silico mutagenesis and dynamic simulation approaches revealed that a novel Cys276Arg variant abolished the cysteine bridge and might contribute toward decreased stability of the TYR protein. Our study expands the mutation spectrum of the TYR and SLC45A2 genes and emphasizes that molecular investigations are essential for accurate disease diagnosis.

SUBMITTER: Bibi N

PROVIDER: S-EPMC7385404 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Publications

Identification and Computational Analysis of Novel <i>TYR</i> and <i>SLC45A2</i> Gene Mutations in Pakistani Families With Identical Non-syndromic Oculocutaneous Albinism.

Bibi Nousheen N Ullah Asmat A Darwesh Lubna L Khan Waqas W Khan Tanzeela T Ullah Kalim K Khan Bushra B Ahmad Wasim W

Frontiers in genetics 20200721

Non-syndromic oculocutaneous albinism (nsOCA) is an inherited disorder of melanin biosynthesis with autosomal recessive mode of inheritance, presenting either hypopigmented or depigmented skin, hair, and eyes. It is genetically heterogeneous with seven loci (OCA1-OCA7) reported to date. In the present study, we have reported three consanguineous families (A, B, C) presenting identical nsOCA phenotypes. Sanger sequencing revealed a novel [NM_000372.5: c.826 T > C, p.(Cys276Arg)] and a recurrent v ...[more]

PMID: 32849781

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Project description:Autosomal recessive conditions are often associated with homozygous mutations showing common ancestral origins and are frequently linked to consanguinity. However, an increasing number of compound heterozygotes are found in diverse, admixed populations. Oculocutaneous albinism (OCA) is a recessive condition caused mainly by mutations in the TYR and OCA2 genes involved in skin pigmentation. We previously screened the TYR and OCA2 genes in Colombian OCA families, identifying both known and novel mutations. Affected family members were found to be either homozygous or compound heterozygous for these gene mutations. Compound heterozygosity, where two different recessive alleles inherited from each parent lead to the expression of an autosomal recessive trait, poses a challenge in genetic diagnosis. Estimating the ancestry of these disease-associated variants, in conjunction with understanding the colonization history of admixed populations, can enhance the precision of association mapping in genetic studies. The aim of this study was to determine the ancestral origins of TYR and OCA2 mutations for OCA patients from two populations located in the Andes region of Colombia-Altiplano Cundiboyacense and Marinilla-Santuario. Comparison of OCA patients, and their unaffected relatives, with global reference populations showed a pattern of European and Native American admixture, with little African ancestry, for these two populations. Mutation-bearing TYR and OCA2 haplotypes from Colombian OCA patients were compared against haplotypes from Spanish, Native American, and Sephardic Jewish reference populations to infer their ancestral origins. For 12 OCA1 patients from the Altiplano Cundiboyacense region, 21 out of 24 mutated TYR haplotypes show Spanish origins, two show Native American origins, and one shows a Sephardic Jewish origin. The two Native American TYR haplotypes, and the single Sephardic Jewish haplotype, are all found in compound heterozygote patients, paired with the predominant Spanish TYR haplotype G47D. OCA in these three patients is a result of genetic admixture that brought together disease-causing mutations with distinct ancestral origins. Both OCA2 patients from the Marinilla-Santuario region show homozygous OCA2 mutations with a Spanish origin. These findings underscore the complexity of the genetic architecture of Mendelian disease in admixed American populations, with both consanguinity and admixture contributing to the risk of autosomal recessive OCA in Colombia.

Dataset Information

Identification and Computational Analysis of Novel TYR and SLC45A2 Gene Mutations in Pakistani Families With Identical Non-syndromic Oculocutaneous Albinism.

Publications

Identification and Computational Analysis of Novel <i>TYR</i> and <i>SLC45A2</i> Gene Mutations in Pakistani Families With Identical Non-syndromic Oculocutaneous Albinism.

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