Prenatal diagnosis of oculocutaneous albinism type II and discovery of two novel mutations

Objective: To investigate the genotype of oculocutaneous albinism type II (OCA2) and perform prenatal gene diagnosis for OCA2. Methods: Peripheral blood samples were collected from a 9-year-old girl with OCA and her parents, the mother being pregnant. PCR, automatic sequence analysis and denaturing high performance liquid chromatography (DHPLC) were used to analyze the TYR gene and P gene so as to screen the OCA genes. Amniocentesis was conducted when the mother was 20-week pregnant and the amniotic cells underwent screening of the 2 specific mutations. Peripheral blood samples were collected from 100 healthy persons without phenotype of OCA to undergo genetic analysis. Results: The TYR gene of the proband did not show any mutation, and 2 new mutations were found in her P gene: p. N476D (c. 1426 A > G) and p. Y827H (c. 2479T > C). Her father and mother were heterozygote of Y827H and N476D respectively. Based on these findings the amniotic cells underwent sequencing of enlarged fragments of the exons 14 and 24 containing the mutation sites. The result showed that the fetus only got the maternal N476D mutation and didnt get the paternal Y827H mutation. So the fetus was predicted to be a carrier of OCA2 with normal appearance. The baby was born normal later as predicted. None of these 2 mutations was found in the 100 healthy persons. Conclusion: This is a success of prenatal gene diagnosis of OCA2. Two novel mutations of the P gene related to OCA have been discovered.