Review of Genotype-Phenotype Correlations in Usher Syndrome.
Eric Nisenbaum, Torin P Thielhelm, Aida Nourbakhsh and 8 others
PMID 34039936WHAT IT FOUND
Usher syndrome subtypes have different hearing loss patterns: USH1 severe congenital deafness, USH2 high-frequency loss with normal balance, USH3 progressive post-lingual loss.
Mutation type can change expected course.
Key findings
01Usher syndrome type 1 causes severe to profound hearing loss from birth or the first year, with absent balance reflexes and possible gross motor delays.
02Usher syndrome type 2 usually leaves balance normal and causes frequency-specific hearing loss, while type 3 causes progressive post-lingual hearing loss with balance problems in about half.
03Some genetic links are not settled, and molecular testing can change the diagnosis: CIB2 may not cause Usher syndrome type 1, PDZD7 is disputed, and testing changed diagnosis in 52% of deaf-blind families in one clinic.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
This is a narrative review, not an original study, so it cannot show that any therapy works. It reviewed English-language literature from 2000-2020, so relevant non-English reports may be missing. Some gene associations are uncertain, including CIB2, PDZD7, and HARS. Phenotypes vary within genes and families, so genotype alone may not predict a patient's course. Ongoing gene therapy trials had not reported outcomes.
Declared interests
NIH extramural support is listed in the publication types. The supplied text does not include an author conflict-of-interest declaration.
The easy way to misread this
Do not read this as evidence that gene therapy, cochlear implantation, or vestibular therapy works for Usher syndrome. The paper is a review of genetic and clinical patterns, and it says current treatment is symptom-directed.