Usher syndrome is an autosomal recessive disorder associated with sensorineural hearing impairment and progressive visual loss attributable to retinitis pigmentosa. The syndrome is both clinically and genetically heterogeneous. Of the 3 different clinical types that have been described, ... Usher syndrome is an autosomal recessive disorder associated with sensorineural hearing impairment and progressive visual loss attributable to retinitis pigmentosa. The syndrome is both clinically and genetically heterogeneous. Of the 3 different clinical types that have been described, USH1 (276900), consisting of the association of profound congenital deafness, constant vestibular dysfunction, and prepubertal onset retinitis pigmentosa, is the most severe.
Bashir et al. (2010) reported 4 affected members of a consanguineous Pakistani family with Usher syndrome type IG. The patients had an atypical form of the disorder, with moderate to severe hearing loss, normal vestibular function, and lack ... Bashir et al. (2010) reported 4 affected members of a consanguineous Pakistani family with Usher syndrome type IG. The patients had an atypical form of the disorder, with moderate to severe hearing loss, normal vestibular function, and lack of eyesight problems. However, funduscopy showed mild symptoms of retinitis pigmentosa and pale optic discs in 3 of the older affected patients at ages 13, 15, and 22 years, respectively.
In affected members of Tunisian, German, and Jordanian families segregating Usher syndrome type IG, Weil et al. (2003) identified mutations in the SANS gene (607696.0001-607696.0004).
In 4 affected members of a consanguineous Pakistani family with a ... In affected members of Tunisian, German, and Jordanian families segregating Usher syndrome type IG, Weil et al. (2003) identified mutations in the SANS gene (607696.0001-607696.0004). In 4 affected members of a consanguineous Pakistani family with a mild form of Usher syndrome type IG, Bashir et al. (2010) identified a homozygous 15-bp deletion (163_164+13del15) involving nucleotides in the first exon and intron of the USH1G gene (607696.0006). The mutation was not found in 200 control chromosomes. Investigation of the effect of the mutation was hampered because RNA from patient blood did not show sufficient expression of SANS. In silico analysis predicted that retention of the first intron in the RNA resulting from the mutation would introduce a frameshift and premature termination, which could result in nonsense-mediated mRNA decay. However, if the mRNA is processed, the frameshift would result in a truncated nonfunctional protein of 58 amino acids. The findings indicated that even a truncating mutation in the USH1G gene can result in a relatively mild phenotype.