School of Pathology (ETDs)

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Investigating the genetic cause of oculocutaneous albinism type 2 in individuals of African descent through exome sequencing
(University of the Witwatersrand, Johannesburg, 2024) Mmbi, Phophi Mmapole; Ngcungcu, Thandiswa G.
Oculocutaneous Albinism type 2 (OCA2) is a hypopigmentation disorder caused by variants in the OCA2 gene. A 2.7kb intragenic deletion is known to be the common variant that causes OCA2 in individuals of African descent. This variant accounts for 78% of OCA2-causing variant in the Southern African population. The diagnostic utility for individuals who tested either negative or heterozygous for the common 2.7kb deletion remained unsolved. This study reports on the identification of the NM 000275.3:c.1503+5G>A variant found in 3/8 (37.5%) non-2.7kb deletion OCA2 chromosomes within a small sample of OCA2 patients from the Southern African population, strongly suggesting the possibility of a second common variant, pending a larger screening study. This variant has been previously described in this population, but new variant interpretation tools have now permitted its reclassification. Furthermore, limitations encountered during the interpretation of data step in this study highlight the importance of informative clinical and phenotypic data for improved and sensible interpretation of genetic results.