Identification of a novel mutation in the ß-globin gene 3' untranslated region [+1,506 (A>C)] in a Japanese male with a heterozygous ß-thalassemia phenotype.

ß-Thalassemia (ß-thal) is characterized by the absent or reduced production of ß-globin chains. The precise molecular lesion that causes decreased ß-globin synthesis in ß(+)-thal is difficult to predict when mutations occur in the locus control region (LCR), the promoter, the introns or 3' untranslated regions (3'UTRs). Among them, the role of the 3'UTR of ß-globin gene in mRNA stability is poorly understood, mainly due to very few cases that have mutations in this region. So far, only three mutations have been reported in the 3'UTR of ß-globin gene. Although, it is speculated that some of these reported mutations could be associated with mRNA stability, the precise molecular basis still remains unclear. We report here a novel mutation in the ß-globin gene 3'UTR [+1,506 (A>C)] in a 31-year-old Japanese male with hematological parameters suggestive of heterozygous ß-thal. Further functional studies on this novel mutation reported here, may help in understanding of the regulation and expression of the ß-globin gene and its products.

Duplications of BHLHA9 are associated with ectrodactyly and tibia hemimelia inherited in non-Mendelian fashion.

BACKGROUND: Split-hand/foot malformation (SHFM)-also known as ectrodactyly-is a congenital disorder characterised by severe malformations of the distal limbs affecting the central rays of hands and/or feet. A distinct entity termed SHFLD presents with SHFM and long bone deficiency. Mouse models suggest that a defect of the central apical ectodermal ridge leads to the phenotype. Although six different loci/mutations (SHFM1-6) have been associated with SHFM, the underlying cause in a large number of cases is still unresolved. METHODS: High resolution array comparative genomic hybridisation (CGH) was performed in patients with SHFLD to detect copy number changes. Candidate genes were further evaluated for expression and function during limb development by whole mount in situ hybridisation and morpholino knock-down experiments. RESULTS: Array CGH showed microduplications on chromosome 17p13.3, a locus previously associated with SHFLD. Detailed analysis of 17 families revealed that this copy number variation serves as a susceptibility factor for a highly variable phenotype with reduced penetrance, particularly in females. Compared to other known causes for SHFLD 17p duplications appear to be the most frequent cause of SHFLD. A ~11.8 kb minimal critical region was identified encompassing a single gene, BHLHA9, a putative basic loop helix transcription factor. Whole mount in situ hybridisation showed expression restricted to the limb bud mesenchyme underlying the apical ectodermal ridge in mouse and zebrafish embryos. Knock down of bhlha9 in zebrafish resulted in shortening of the pectoral fins. CONCLUSIONS: Genomic duplications encompassing BHLHA9 are associated with SHFLD and non-Mendelian inheritance characterised by a high degree of non-penetrance with sex bias. Knock-down of bhlha9 in zebrafish causes severe reduction defects of the pectoral fin, indicating a role for this gene in limb development.

Internet-based approach to population screening for common hemoglobinopathies in United Arab Emirates.

This article reports on efforts to overcome common hurdles that were faced during population-based screening for common hemoglobinopathies in the United Arab Emirates. An Internet-based approach was designed and implemented to increase the acceptance of the screening program. The process involved: an awareness campaign, a simple bilingual (Arabic/English) online consent form and registration process, the use of a barcode for sample labeling, an equipment upgrade, electronic communication of a successful registration process, test results, and a counseling process. Before the implementation of the Internet-based system, great concern was noted among the clients in terms of the availability of accurate and timely test results, the need for pretest and post-test counseling, and the way that their personal health information was handled. Lapses in information exchange between the clients who participated in the screening program for the carrier state of inherited disorders and the screening laboratory posed significant challenges. The emphasis on confidentiality and the ease of access to services was instrumental in increasing the level of acceptance of these services in our community. Based on an analysis of > 10,000 samples, we conclude that Internet-based reporting holds much promise for improving the quality of care that clients receive.

Genomewide linkage scan for split-hand/foot malformation with long-bone deficiency in a large Arab family identifies two novel susceptibility loci on chromosomes 1q42.2-q43 and 6q14.1.

Split-hand/foot malformation with long-bone deficiency (SHFLD) is a rare, severe limb deformity characterized by tibia aplasia with or without split-hand/split-foot deformity. Identification of genetic susceptibility loci for SHFLD has been unsuccessful because of its rare incidence, variable phenotypic expression and associated anomalies, and uncertain inheritance pattern. SHFLD is usually inherited as an autosomal dominant trait with reduced penetrance, although recessive inheritance has also been postulated. We conducted a genomewide linkage analysis, using a 10K SNP array in a large consanguineous family (UR078) from the United Arab Emirates (UAE) who had disease transmission consistent with an autosomal dominant inheritance pattern. The study identified two novel SHFLD susceptibility loci at 1q42.2-q43 (nonparametric linkage [NPL] 9.8, P=.000065) and 6q14.1 (NPL 7.12, P=.000897). These results were also supported by multipoint parametric linkage analysis. Maximum multipoint LOD scores of 3.20 and 3.78 were detected for genomic locations 1q42.2-43 and 6q14.1, respectively, with the use of an autosomal dominant mode of inheritance with reduced penetrance. Haplotype analysis with informative crossovers enabled mapping of the SHFLD loci to a region of approximately 18.38 cM (8.4 Mb) between single-nucleotide polymorphisms rs1124110 and rs535043 on 1q42.2-q43 and to a region of approximately 1.96 cM (4.1 Mb) between rs623155 and rs1547251 on 6q14.1. The study identified two novel loci for the SHFLD phenotype in this UAE family.

Genomewide scan for nonsyndromic cleft lip and palate in multigenerational Indian families reveals significant evidence of linkage at 13q33.1-34.

Nonsyndromic cleft lip with or without cleft palate (CL-P) is a common congenital anomaly with incidence ranging from 1 in 300 to 1 in 2,500 live births. We analyzed two Indian pedigrees (UR017 and UR019) with isolated, nonsyndromic CL-P, in which the anomaly segregates as an autosomal dominant trait. The phenotype was variable, ranging from unilateral to bilateral CL-P. A genomewide linkage scan that used approximately 10,000 SNPs was performed. Nonparametric linkage (NPL) analysis identified 11 genomic regions (NPL>3.5; P<.005) that could potentially harbor CL-P susceptibility variations. Among those, the most significant evidence was for chromosome 13q33.1-34 at marker rs1830756 (NPL=5.57; P=.00024). This was also supported by parametric linkage; MOD score (LOD scores maximized over genetic model parameters) analysis favored an autosomal dominant model. The maximum LOD score was 4.45, and heterogeneity LOD was 4.45 (alpha =100%). Haplotype analysis with informative crossovers enabled the mapping of the CL-P locus to a region of approximately 20.17 cM (7.42 Mb) between SNPs rs951095 and rs726455. Thus, we have identified a novel genomic region on 13q33.1-34 that harbors a high-risk variant for CL-P in these Indian families.

Ectrodactyly with aplasia of long bones (OMIM; 119100) in a large inbred Arab family with an apparent autosomal dominant inheritance and reduced penetrance: clinical and genetic analysis.

Ectrodactyly with aplasia of long bones syndrome is one of the most recognizable defects involving the extremities. We have studied a very large eight-generation consanguineous Arab family from the United Arab Emirates (UAE) with multiple severe limb anomalies resembling this condition (OMIM; 119100), for which the affected gene is unknown. The pedigree consists of 145 individuals including 23 affected (14 males/9 females) with limb anomalies. Of these, 18 had tibial aplasia (TA) usually on the right side. The expression of the phenotype was variable and ranged from bilateral to unilateral TA with ectrodactyly and other defects of the extremities. The mode of inheritance appears to be autosomal dominant with reduced penetrance. There were 10 consanguineous marriages observed in this pedigree. This could suggest possible pseudodominance due to high frequency of the mutant allele. Candidate loci for the described syndrome include GLI3 (OMIM: 165240) on 7p13, sonic hedgehog; (OMIM: 600725) on 7q36, Langer-Giedion syndrome (OMIM: 150230) on 8q24.1 and split-hand/foot malformation 3 (OMIM: 600095) on 10q24. In addition, bilateral tibial hemimelia and unilateral absence of the ulna was previously observed to co-segregate with deletion of 8q24.1. Two-point linkage and haplotype analyses did not show the involvement of the above regions in this family.