[Analysis of TYR gene variant in a patient with Oculocutaneous albinism]

To explore the genetic basis of a patient with suspected Oculocutaneous albinism (OCA).

An OCA patient presented at the West China Second Hospital of Sichuan University and his mother were selected as the study subjects. Peripheral blood samples were collected for the extraction of, genomic DNA, and whole exome sequencing (WES) was carried out. Candidate variants were verified through specific primer amplification, Sanger sequencing, and agarose gel electrophoresis. Bioinformatic analysis and pathogenicity rating were conducted on the candidate variants. This study has been approved by the Medical Ethics Committee of West China Second Hospital (No. 2024-228).

Genetic testing revealed that the patient had harbored variants in exon 1 of the TYR gene, including a c.157G>T (p.G53C) missense variant and a c.609dup (p.A204fs) frameshifting variant. Specific primer amplification and Sanger sequencing, combined with agarose gel electrophoresis, confirmed that these are compound heterozygous variants. Based on the guidelines from the ACMG, the c.157G>T was rated as likely pathogenic, and c.609dup was rated as pathogenic. Alphafold3 predicted that the variant proteins had significant structural changes.

The patient was diagnosed with OCA due to compound heterozygous variants of the TYR gene. Discovery of the c.609dup variant has enriched the mutational spectrum of OCA and provided a basis for genetic counseling and prenatal diagnosis for this patient.