Identification of Genetic Mutations in TYR and OCA2 Genes in Congenital Families with Oculocutaneous Albinism (OCA)

Abstract

Aim: The objective of the present study was to recruit congenital families of oculocutaneous albinism (OCA) and mutations in TYR and OCA2 genes are identified, which is further expanding the mutation spectrum in this population. Methods: Two consanguineous families with OCA were recruited and whole blood was collected. Clinical examination was carried out to determine the visual acuity and related eye, skin and hair examinations. Genomic DNA was extracted by standard phenol-chloroform method. Targeted exome sequencing by TruSight one sequencing panel sequencing was carried out. Sanger sequencing was performed for mutation detection in tyrosinase (TYR) and the OCA2 genes and co-segregation in OCA families. Results: Clinically, the affected individuals of two OCA families showed clinical characteristics including white to pale skin, white or blonde hairs, irritant to light, nystagmus and reduced vision. DNA sequencing showed the genetic mutation of TYR and OCA2 genes in two OCA families. In family 1, the nucleotide variant (c.1255G>A; p.Gly419Arg) was detected inTYR gene, while in another family, the splice-site variant c.1045-15T>G was identified in OCA2. Conclusion: This study concluded that identification of TYR and OCA2 mutations in OCA disease are commonly associated with the population where the consanguinity is persistent. These findings expanded the molecular basis of oculocutaneous albinism in Pakistani families and established the mode of genetic counselling and for diagnostic outcome. Keywords: Consanguineous families; Oculocutaneous albinism (OCA); mutations; tyrosinase (TYR); OCA2 gene.