A single-nucleotide polymorphism of the DAZL gene promoter confers susceptibility to spermatogenic failure in the Taiwanese Han.

BACKGROUND: Deleted in AZoospermia-like (DAZL) is an autosomal homologue of Y chromosome-linked DAZ gene located on chromosome 3p24. DAZL is only expressed in the gonads and is critical to germ cell development in different species. However, the regulation of DAZL has not been explored. METHODS: Reporter assays, electrophoretic mobility shift assays, supershift assays and bisulfate sequencing were used to identify the core promoter region of DAZL. Sequence analysis was used to identify single-nucleotide polymorphisms (SNPs) in the promoter region. A total of 337 infertile men with abnormal semen parameters and 203 fertile men with normal semen parameters were subjected to sequence analysis of the DAZL promoter region. RESULTS: The DAZL gene core promoter is located 1 kb upstream of the transcription start site. Three SNPs (-792G>A, -669A>C and -309T>C) were identified in our population. Of these three SNPs, -792G>A was more prevalent in the infertile men (P= 0.0005). Quantitative analysis revealed that genotypes of -792G>A had effects on sperm concentration (P= 0.0025) and motility (P= 1.5 × 10(-7)). The G to A substitution was associated with decreased binding of the nuclear respiratory factor-1 (NRF-1) to the promoter region and decreased reporter gene activity. CONCLUSION: We have identified the core promoter of the human DAZL gene. We also provide preliminary evidence for the role of a novel SNP of the DAZL gene promoter in human spermatogenic failure.

Screening of Prader-Willi syndrome and Angelman syndrome in school children with moderate to profound mental retardation in southern Taiwan.

BACKGROUND AND PURPOSE: Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are caused by deficiencies of gene expression from paternal or maternal chromosome 15q11-q13, respectively. The study was conducted to estimate the prevalence of PWS and AS in children with moderate to profound mental retardation in Taiwan. METHODS: The screening began with methylation studies in all enrolled cases. If methylation results were positive, Fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) was used to determine whether deletion, uniparental disomy, or imprinting mutation was present. RESULTS: Of 1053 children with moderate to profound mental retardation, we identified three cases of AS (0.28%) and one case of PWS (0.09%). CONCLUSIONS: The prevalence of PWS is lower than AS in school children with moderate to profound mental retardation. The greater number of AS identified than that of PWS is most likely a reflection of more severe mental retardation for AS than for PWS.

Isochromosome of Yp in a man with Sertoli-cell-only syndrome.

OBJECTIVE: To address phenotype/genotype correlation in a man with i(Y)(p10). DESIGN: Case report. SETTING: University-based reproductive genetics laboratory. PATIENT(S): A 27-year-old azoospermic man with i(Y)(p10), relatively normal stature, and testicular Sertoli-cell-only syndrome. INTERVENTION(S): Testicular biopsy, cytogenetic study, Y-chromosome deletion mapping analysis, fluorescence in situ hybridization (FISH). MAIN OUTCOME MEASURE(S): Expression of Y-chromosome genes. RESULT(S): We have identified one azoospermic man with i(Y)(p10) of 312 Taiwanese men presenting with a severe spermatogenic defect. Y-chromosome deletion mapping analysis confirmed deletions of all Yq sequences, including a putative growth controlling gene. Fluorescence in situ hybridization (FISH) analysis showed duplication of Yp material. The patient had normal stature considering midparental height. He also had no germ cells in the testicular tissue (Sertoli-cell-only syndrome) resulting from the loss of azoospermia factor in Yq. CONCLUSION(S): Among structural rearrangements of the Y-chromosome, the isochromosome of Yp occurs very rarely. This case is the first reported case of an isochromosome Yp with a detailed description of testicular histology and body height.