Longitudinal phenotypic analysis in patients with connexin 26 (GJB2) (DFNB1) and connexin 30 (GJB6) mutations.
In 15 Belgian subjects with prelingual sensorineural hearing impairment, the connexin 26 (GJB2) gene and the connexin 30 (GJB6) gene were analyzed for the presence of the 35delG mutation and the delta(GJB6-D13S1830) deletion first described by del Castillo et al in 2002. Seven patients were found to be homozygous for the 35delG mutation; 7 were combined heterozygotes for the 35delG mutation and the GJB6 deletion. In 11 subjects, phenotype and genotype were correlated. Significant, transient progression, in the range of 1.7 to 2.7 dB/y, was only found in 2 patients in the first part of the second decade of life. Hearing impairment was otherwise stable, with mean thresholds of 75, 90, and 100 dB at 0.125, 0.25, and 0.5 kHz, respectively, and 100 dB or higher at 1 to 4 kHz. There was no significant difference in hearing impairment between the patients with the homozygous 35delG mutation in GJB2 and those who are heterozygous for both the 35delG mutation and the deletion encompassing part of GJB6.
Department of Otorhinolaryngology, University Hospitals Leuven, Leuven, Belgium.
Christel
C
Stinckens
Hannie
H
Kremer
Erwin
E
van Wijk
Lies H
LH
Hoefsloot
Patrick L M
PL
Huygen
Lieve
L
Standaert
Jean Pierre
JP
Fryns
Cor W R J
CW
Cremers
D000293:Adolescent; D000328:Adult; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000502:physiology; D002648:Child; D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins / Q000235:genetics*; D053938:DNA Fragmentation; D004252:DNA Mutational Analysis; D005500:Follow-Up Studies; D017353:Gene Deletion; D005838:Genotype; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D010375:Pedigree; D010641:Phenotype; D017354:Point Mutation / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012720:Severity of Illness Index
D000075302:Connexin 30; D017630:Connexins; C000607042:GJB2 protein, human; C491020:GJB6 protein, human; D000072259:Connexin 26