Novel ABHD12 mutations in PHARC patients: the differential diagnosis of deaf-blindness.

OBJECTIVE

This study examines ABHD12 mutation analysis in 2 PHARC patients, originally thought to be Usher syndrome.

METHODS

The ABHD12 gene of 2 patients, who suffered from deaf-blindness and dysfunctional central and peripheral nervous systems, were sequenced.

RESULTS

We identified that both cases carried the same novel splice site mutation in the ABHD12 gene. However, 1 had epilepsy and the other had peripheral neuropathy. Based on haplotype analysis, the mutation is likely not a hot spot, but rather could be attributable to a common ancestor.

CONCLUSION

This study shows that PHARC has phenotypic variability, even within a family, which is consistent with previous reports. Differential diagnosis of "deaf-blindness" diseases is crucial. Confirming the presence of associated symptoms is necessary for differentiating some deaf-blindness syndromes. In addition, mutation analysis is a useful tool for confirming the diagnosis.