MYO7A p.Ile134Asn

The c.401T>A (p.Ile134Asn) is a missense variant in MYO7A predicted to cause a substitution of isoleucine to asparagine at amino acid 134. The filtering allele frequency (the lower threshold of the 95% CI of 60/1179894) of this variant is 0.004019% in the European (non-Finnish) population which meets the threshold (≤0.00007, 0.007%) defined by the ClinGen Hearing Loss Expert Panel for PM2_Supporting for autosomal recessive Usher syndrome (PM2_Supporting). The REVEL computational prediction tool produced a score of 0.938, which is above the threshold necessary to apply PP3 (PP3). This variant has been detected in 7 probands with Usher syndrome. For 2 of those probands, pathogenic variants (c.19-1G>A and p.Gly214Arg) were observed in trans, and in the other 5 probands, a pathogenic variant was observed with unknown phase (4.5 points, PM3_Very Strong, PMIDs: 25468891, 26969326, 33089500, 37510321, Partners LMM Internal Data ClinVar SCV000059786.6). The variant has been reported to segregate with hearing loss in one affected family member (PP1, Partners LMM Internal Data ClinVar SCV000059786.6). At least one patient with this variant displayed features of sensorineural hearing loss and retinitis pigmentosa, which are consistent for Usher syndrome, a condition highly specific for MYO7A (PP4, Partners LMM Internal Data ClinVar SCV000059786.6). In summary, this variant meets criteria to be classified as pathogenic for autosomal recessive Usher syndrome based on the ACMG/AMP criteria applied as specified by the ClinGen Hearing Loss Expert Panel (PM3_Very Strong, PM2_Supporting, PP1, PP3, PP4). (ClinGen Hearing Loss VCEP specifications version 2; 9/18/2024).