Description
DNA sequence analysis of the TYR gene demonstrated a sequence change, c.1205G>A, in exon 4 that results in an amino acid change, p.Arg402Gln. The p.Arg402Gln substitution is a well-documented temperature-sensitive reduced function allele that alone is not sufficient to cause an oculocutaneous albinism phenotype. However, the p.Arg402Gln substitution, if found in compound heterozygous state with a pathogenic mutation, may be associated with a mild oculocutaneous albinism type 1B (OCA1B) or ocular albinism (OA) phenotype (PMIDs: 7704033, 19938076, 18463683, 18326704, 23504663). The p.Arg402Gln substitution has been described in the gnomAD database with a high population frequency of 28% in the European American population (dbSNP rs1126809). Some studies have suggested that the p.Arg402Gln substitution is not associated with mild OCA1B or OA phenotype, due to its high frequency in the general population and the presence of this variant in trans with a pathogenic variant in unaffected parents (PMID: 19208379). It has been proposed that the p.Arg402Gln variant causes a partial albinism phenotype only when paired with certain genetic backgrounds (PMIDs: 7704033, 19938076) and multiple studies have shown that the p.Arg402Gln variant is more common in OCA patients with one TYR pathogenic variant than in patients with two pathogenic variants (PMIDs: 18463683, 18326704, 19938076, 23504663).
# | Sample | Method | Observation |
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Origin | Affected | Number tested | Tissue | Purpose | Method | Individuals | Allele frequency | Families | Co-occurrences |
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1 | germline | no | not provided | not provided | not provided | | not provided | not provided | not provided | not provided |