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. 2022 Sep;36(9):e24625.
doi: 10.1002/jcla.24625. Epub 2022 Jul 23.

Genetic analyses of Vietnamese patients with oculocutaneous albinism

Ma Thi Huyen Thuong  1   2 , Luong Thi Lan Anh  3 , Vu Phuong Nhung  1 , Tran Thi Bich Ngoc  1 , Hoang Thu Lan  3 , Doan Kim Phuong  3 , Nguyen Hai Ha  1   2 , Nong Van Hai  1   2 , Nguyen Dang Ton  1   2
Affiliations

Genetic analyses of Vietnamese patients with oculocutaneous albinism

Ma Thi Huyen Thuong et al. J Clin Lab Anal. 2022 Sep.

Abstract

Background: Oculocutaneous albinism (OCA) is an autosomal recessive disease with hypopigmentation in skin, hair, and eyes, causing by the complete absence or reduction of melanin in melanocytes. Many types of OCA were observed based on the mutation in different causing genes relating to albinism. OCA can occur in non-syndromic and syndromic forms, where syndromic OCA coexists with additional systemic consequences beyond hypopigmentation and visual-associated symptoms.

Methods: We performed whole exome sequencing in seven affected individuals (P1-P7) for mutation identification, and then, Sanger sequencing was used for verifications.

Results: Among them, five patients (P1-P5) have mutations on TYR gene including c.346C > T, c.929insC, c.115 T > C, and c.559_560ins25. The mutation on OCA2 and HPS1 genes was found in patient 6 (P6, OCA2 c.2323G > A) and patient 7 (P7, HPS1 c.972delC), respectively. Confirmation in parents (except the family of the elderly patient, P5) showed that the mother and the father in each family carried one of the variants that were detected in patients. Additionally, the effective genetic counseling was applied in the third pregnancy of a family with two OCA children (P1 and P2).

Conclusion: To our best knowledge, this is the first case with a novel homozygous missense mutation (c.115 T > C, p.W39R) in the TYR gene. This study provides a broader spectrum of mutations linked to the oculocutaneous albinism, an additional scientific basis for diagnosis, and appropriate genetic counseling for risk couples.

Keywords: HPS1; OCA2; TYR; WES; oculocutaneous albinism; vietnamese.

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Conflict of interest statement

All authors declare that they have no conflict of interest.

Figures

FIGURE 1
FIGURE 1
Clinical features of six albinism cases in Vietnam (patient 6 was not present) with hypopigmentation in skin, hair (white skin and hair in P1, P2, and P5; pinkish‐white skin and light yellow hair in P3 and P4; white skin and brown hair in P7), and iris color arrange from blue (P1, P2, and P7) to brown (P3, P4, and P5)
FIGURE 2
FIGURE 2
Pedigree charts of two families (A and B) and electropherograms of five affected individuals and their families (except the family of P5) with TYR mutations. Full/half black represents patient/carrier individuals. Mutated/normal nucleotides (A and B) and insertion sequence (C) were marked with red/blue arrows and red box, respectively.
FIGURE 3
FIGURE 3
Pedigree chart and electropherograms of P6 family with OCA2 mutation. Full/half black represents patient/carrier individuals. Mutated/normal nucleotides were marked with red/blue arrows
FIGURE 4
FIGURE 4
Pedigree chart and electropherograms of P7 family with HPS1 mutation. Full/half black represents patient/carrier individuals. Mutated nucleotides were marked with red arrows
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