Usher syndrome (USH) is an autosomal recessive disorder characterized by bilateral sensorineural deafness and progressive loss of vision due to retinitis pigmentosa. It is the most frequent cause of deafness and concurrent blindness, with a prevalence of 1 in 16,000 to 1 in 50,000. USH can be classified into three clinical subtypes, the most severe of which is type 1 Usher syndrome (USH I), characterized by profound prelingual hearing loss, vestibular areflexia, and prepubertal onset of retinitis pigmentosa. Although the disorder is panethnic, and multiple causative genes have been identified, one mutation in the PCDH15 gene (p.R245X) has a carrier frequency of approximately 1 in 147 in the Ashkenazi Jewish population. Screening this single mutation will detect at least 75% of carriers in this population**. Carrier screening for USH I may be considered for individuals of Eastern European (Ashkenazi) Jewish ancestry before/during pregnancy.
Full gene sequencing is available for reproductive partners of known mutation carriers. Prenatal diagnosis is also available. Prior to ordering prenatal testing, please contact our laboratory at 212-241-7518 to discuss.
** A carrier detection rate of 75% is lower than that of the other conditions offered on this panel. Please be aware of the limitations of this test.
1. Ahmed ZM et al., (2003) The molecular genetics of Usher syndrome. Clin Genet. Jun63(6):431-44.
2. Alagramam KN et al., (2001) Mutations in the novel protocadherin PCDH15 cause Usher syndrome type 1F. Hum Mol Genet. Aug 110(16):1709-18.
3. Ben-Yosef T et al., (2003) A mutation of PCDH15 among Ashkenazi Jews with the type 1 Usher syndrome. N Engl J Med. Apr 24348(17):1664-70.
4. Petit C (2001) Usher syndrome: from genetics to pathogenesis. Annu Rev Genomics Hum Genet. 2:271-97.
5. Scott, S.A., Edelmann, L., Liu, L., Luo, M., Desnick, R.J. and Kornreich, R. Experience with carrier screening and prenatal diagnosis for sixteen Ashkenazi Jewish Genetic Diseases. Hum. Mutat. 31:1-11, 2010.
Amniotic Fluid: 10 ml in conical tube
Cultured Cells: two confluent T-25 flasks
Additionally, please send:5-10 ml maternal blood in EDTA (lavender top) required to perform MCC studies on all prenatal samples and in case maternal confirmation studies are necessary
5-10 ml paternal blood in EDTA (lavender top) in case paternal confirmation studies are necessary