The R245X mutation of PCDH15 in Ashkenazi Jewish children diagnosed with nonsyndromic hearing loss foreshadows retinitis pigmentosa

Usher syndrome is a frequent cause of the combination of deafness and blindness due to retinitis pigmentosa (RP). Five genes are known to underlie different forms of Usher syndrome type I (USH1). In the Ashkenazi Jewish population, the R245X mutation of the PCDH15 gene may be the most common cause of USH1 (Ben-Yosef T, Ness SL, Madeo AC, Bar-Lev A, Wolfman JH, Ahmed ZM, Desnick RK, Willner JP, Avraham KB, Ostrer H, Oddoux C, Griffith AJ, Friedman TB N Engl J Med 348: 1664-1670, 2003). To estimate what percentage of Ashkenazi Jewish children born with profound hearing loss will develop RP due to R245X, we examined the prevalence of the R245X PCDH15 mutation and its carrier rate among Ashkenazi Jews in Israel. Among probands diagnosed with nonsyndromic hearing loss not due to mutations of connexin 26 (GJB2) and/or connexin 30 (GJB6), and below the age of 10, 2 of 20 (10%) were homozygous for the R245X mutation. Among older nonsyndromic deaf individuals, no homozygotes were detected, although one individual was heterozygous for R245X. The carrier rate of the R245X mutation among the normal hearing Ashkenazi population in Israel was estimated at 1%. Ashkenazi Jewish children with profound prelingual hearing loss should be evaluated for the R245X PCDH15 mutation and undergo ophthalmologic evaluation to determine whether they will develop RP. Rehabilitation can then begin before loss of vision. Early use of cochlear implants in such cases may rescue these individuals from a dual neurosensory deficit.     

Müllerian anomalies, hearing loss, and connexin 26 mutations

In a study of the possible inter-relationship among müllerian anomalies, hearing loss, and connexin 26 mutations, we evaluated all women in whom müllerian anomalies were diagnosed on hysterosalpingography during a 6-year period (n = 24/519). Audiometric testing revealed five (22.7%) with unrecognized sensorineural hearing loss; however, on genetic evaluation, none harbored a connexin 26 mutation.     

Association of serum relaxin with striae gravidarum in pregnant women

Aims  

The cause of striae gravidarum is still unclear. The study objective was to test the hypothesis that relaxin is involved in the process of striae gravidarum appearance during pregnancy.     

Urea uptake enhances barrier function and antimicrobial defense in humans by regulating epidermal gene expression

Urea is an endogenous metabolite, known to enhance stratum corneum hydration. Yet, topical urea anecdotally also improves permeability barrier function, and it appears to exhibit antimicrobial activity. Hence, we hypothesized that urea is not merely a passive metabolite, but a small-molecule regulator of epidermal structure and function. In 21 human volunteers, topical urea improved barrier function in parallel with enhanced antimicrobial peptide (AMP; LL-37 and β-defensin-2) expression. Urea stimulates the expression of, and is transported into, keratinocytes by two urea transporters (UTs), UT-A1 and UT-A2, and by aquaporins 3, 7, and 9. Inhibitors of these UTs block the downstream biological effects of urea, which include increased mRNA and protein levels of (i) transglutaminase-1, involucrin, loricrin, and filaggrin, (ii) epidermal lipid synthetic enzymes, and (iii) cathelicidin/LL-37 and β-defensin-2. Finally, we explored the potential clinical utility of urea, showing that topical urea applications normalized both barrier function and AMP expression in a murine model of atopic dermatitis. Together, these results show that urea is a small-molecule regulator of epidermal permeability barrier function and AMP expression after transporter uptake, followed by gene regulatory activity in normal epidermis, with potential therapeutic applications in diseased skin.     

Chromosomal mapping and phenotypic characterization of hereditary otosclerosis linked to the OTSC4 locus

OBJECTIVE: To perform chromosomal mapping and clinical analysis of hereditary otosclerosis linked to the fourth locus for otosclerosis (OTSC4) in an Israeli family. DESIGN: Pedigree study. SETTING: A genetics of hearing loss research laboratory, a clinical genetics laboratory, a center for speech and hearing, and an otolaryngology department at a university and medical centers in Israel. SUBJECTS: An Israeli family of which 24 members were ascertained and a pedigree was constructed; 12 members had otosclerosis. INTERVENTIONS: Confirmation of otosclerosis by surgery (3 subjects) and by audiologic evaluation, medical history, and family history (9 subjects), and whole-genome scanning to identify the chromosomal region of the mutant locus. MAIN OUTCOME MEASURES: Chromosomal location of the otosclerosis locus. RESULTS: Linkage to the 16q21-23.2 interval was identified and confirmed with a logarithm of odds (LOD) score of 3.97 at theta = 0. The new locus for otosclerosis was designated OTSC4. The OTSC4 interval of 9 to 10 megabase includes several genes involved in the immune system and bone homeostasis that may be good candidates for genes otosclerosis. CONCLUSION: The elucidation of the OTSC4 gene may disclose the etiology of the disorder, and the functional and structural analysis of the protein may open new options for diagnosis, treatment, and prevention of otosclerosis.     

Connexin-associated deafness and speech perception outcome of cochlear implantation

OBJECTIVE: To compare performance after cochlear implantation in children with mutations in connexin (Cx) 26 (GJB2) or Cx30 (GJB6) and children with deafness of unknown etiology. DESIGN: Genetic analysis and speech perception evaluation was performed in the children with and without Cx mutations who had undergone cochlear implantation. Speech perception performance was retrospectively analyzed 6, 12, 24, 36, and 48 months after implantation. Test material was selected according to the child's age and cognitive and language abilities. SETTING: The study took place at speech and hearing and genetic centers of a hospital in the central part of Israel and the genetics departments of 3 additional centrally located hospitals. PATIENTS: A total of 30 children who had undergone cochlear implantation were selected for the study, with control patients matched according to age at implantation, duration of implant use, and mode of communication. There was no evidence for additional disabilities or handicaps in either group. MAIN OUTCOME MEASURES: Speech perception measurements included a questionnaire, as well as closed and open-set tests. RESULTS: Overall, the 2 groups showed significant improvement in speech perception results after implantation. Four years after implantation, both groups achieved mean open-set speech perception scores of approximately 60%, 75%, and 90% for monosyllabic, 2 syllables, and words in sentences tests, respectively. CONCLUSIONS: There were no apparent differences in speech perception performance after implantation between the children with Cx mutations and children with deafness of unknown etiology. These data have important implications as a prognostic indicator when counseling candidates for cochlear implantation.