Androgen receptor genotyping in a large Australasian cohort with androgen insensitivity syndrome; identification of four novel mutations

We genotyped the androgen receptor (AR) gene in 31 Australasian patients with androgen insensitivity syndrome (AIS). The entire coding region of AR was examined including analysis of polymorphic CAG and GGN repeats in all patients. AR defects were found in 66.7% (6/9) of patients with complete AIS (CAIS) and 13.6% (3/22) of patients with partial AIS (PAIS). A novel deletion (N858delG) leading to a premature stop codon was found in CAIS patient P1. CAIS patient P2 has a novel deletion (N2676delGAGT) resulting in a stop at codon 787. These mutations would result in inactivation of AR protein. A novel insertion of a cysteine residue in the first zinc finger of the AR DNA-binding domain (N2045_2047dupCTG) was found in CAIS patient P3. PAIS patient P4 has a novel amino acid substitution (Arg760Ser) in the AR ligand binding domain, which may impair ligand binding. Five patients were found to have previously reported AR mutations and no mutations were identified in the remaining patients.

Deletions involving long-range conserved nongenic sequences upstream and downstream of FOXL2 as a novel disease-causing mechanism in blepharophimosis syndrome

The expression of a gene requires not only a normal coding sequence but also intact regulatory regions, which can be located at large distances from the target genes, as demonstrated for an increasing number of developmental genes. In previous mutation studies of the role of FOXL2 in blepharophimosis syndrome (BPES), we identified intragenic mutations in 70% of our patients. Three translocation breakpoints upstream of FOXL2 in patients with BPES suggested a position effect. Here, we identified novel microdeletions outside of FOXL2 in cases of sporadic and familial BPES. Specifically, four rearrangements, with an overlap of 126 kb, are located 230 kb upstream of FOXL2, telomeric to the reported translocation breakpoints. Moreover, the shortest region of deletion overlap (SRO) contains several conserved nongenic sequences (CNGs) harboring putative transcription-factor binding sites and representing potential long-range cis-regulatory elements. Interestingly, the human region orthologous to the 12-kb sequence deleted in the polled intersex syndrome in goat, which is an animal model for BPES, is contained in this SRO, providing evidence of human-goat conservation of FOXL2 expression and of the mutational mechanism. Surprisingly, in a fifth family with BPES, one rearrangement was found downstream of FOXL2. In addition, we report nine novel rearrangements encompassing FOXL2 that range from partial gene deletions to submicroscopic deletions. Overall, genomic rearrangements encompassing or outside of FOXL2 account for 16% of all molecular defects found in our families with BPES. In summary, this is the first report of extragenic deletions in BPES, providing further evidence of potential long-range cis-regulatory elements regulating FOXL2 expression. It contributes to the enlarging group of developmental diseases caused by defective distant regulation of gene expression. Finally, we demonstrate that CNGs are candidate regions for genomic rearrangements in developmental genes.

Principal mutation hotspot for central core disease and related myopathies in the C-terminal transmembrane region of the RYR1 gene

The congenital myopathies are a group of disorders characterised by the predominance of specific histological features observed in biopsied muscle. Central core disease and nemaline myopathy are examples of congenital myopathies that have specific histological characteristics but significantly overlapping clinical pictures. Central core disease is an autosomal dominant disorder with variable penetrance which has been linked principally to the gene for the skeletal muscle calcium release channel (RYR1). Two recent reports have identified the 3' transmembrane domain of this gene as a common site for mutations. Two other studies have reported single families that have features of both central core disease and nemaline myopathy (core/rod disease) caused by mutations in RYR1. Screening of the 3' region (exons 93-105) of the RYR1 gene for mutations in 27 apparently unrelated patients with either central core disease or core/rod disease by single strand conformation polymorphism analysis and DNA sequencing identified three described and nine novel mutations in 15 patients.

Ectrodactyly and glaucoma associated with a 7q21.2-q31.2 interstitial deletion

An infant with ectrodactyly, glaucoma, cleft palate, congenital heart defect and genital anomalies associated with a 7(q21.2q31.2) deletion is presented. Glaucoma and ectrodactyly in association with a 7q deletion has not been previously reported. We recommend that early ophthalmological assessment is required in infants with such deletions.

Investigation of a cryptic interstitial duplication involving the Prader-Willi/Angelman syndrome critical region

A 3-year-old female referred with developmental delay, hypotonia and seizures was found to have a cryptic interstitial duplication of the Prader-Willi/Angelman critical region (PWACR). Her clinical features form part of a common phenotype characteristic of PWACR duplications including developmental delay, behavioural problems and speech difficulties. Microsatellite analysis showed that the duplication had arisen de novo, was maternal in origin and involved the entire 4-Mb PWACR between the common deletion breakpoints. The existence of cryptic rearrangements emphasises the need for molecular tests alongside conventional cytogenetics when investigating abnormalities involving this imprinted region.

Crossover analysis in a British family suggests that Coffin-Lowry syndrome maps to a 3.4-cM interval in Xp22

Coffin-Lowry syndrome (CLS; MIM 303600) in an uncommon X-linked disorder causing mental retardation and skeletal abnormalities. Most recently it was mapped to a 5.6-centimorgan (cM) region of Xp22, flanked distally by AFM291wf5 and proximally by DXS1052 [Biancalana et al., 1994: Genomics 22:617-625]. We present information which supports this localization and further narrows the region to approximately 3.4 cM. A recombination in a carrier from a British family mean that DXS365 is the closest proximal flanking marker identified to date for the region thought to contain the CLS gene. This information reduces the region of interest by approximately 2.2 cM, a significant decrease in terms of the scale of effort which will be required to isolate and analyze candidate genes.

Nevoid basal cell carcinoma syndrome: review of 118 affected individuals

One hundred eighteen cases of nevoid basal cell carcinoma syndrome (NBCCS, Gorlin's syndrome or basal cell nevus syndrome) are presented in this study. In aiming to ascertain all the affected families in Australia, we have examined the largest series to date. Relative frequencies of associated complications are presented and compared with those of the recent English survey by Evans et al. [J Med Genet 30:460-464, 1993]. The frequencies of most manifestations are similar. However, one major difference is that the multiple basal cell carcinomas are manifest from an earlier age in the Australian population, which probably reflects greater exposure to ultraviolet radiation. Of the 64 families ascertained, 37 represented simplex cases, and, accordingly, the apparent new mutation rate is surprisingly high (14-81%) given the lack of impact of NBCCS on reproductive capabilities. There is some evidence to suggest that this may be attributable to anticipation.

Femoral hypoplasia unusual facies syndrome with preaxial polydactyly

Preaxial polydactyly of the foot is an unusual feature in femoral hypoplasia unusual facies syndrome, having been recorded with certainty in only two previous reports. We now add a further two instances of this rare association and emphasize that this finding should not preclude the underlying syndromic diagnosis.

Further localization of the gene for nevoid basal cell carcinoma syndrome (NBCCS) in 15 Australasian families: linkage and loss of heterozygosity

Nevoid basal cell carcinoma syndrome (NBCCS; basal cell nevus syndrome or Gorlin syndrome) is a cancer-predisposition syndrome characterized by multiple basal cell carcinomas (BCCs) and diverse developmental defects. The gene for NBCCS has been mapped to 9q23.1-q31 in North American and European families. In addition, loss of heterozygosity (LOH) for genetic markers in this region has been detected in sporadic BCCs, indicating that the NBCCS gene is probably a tumor-suppressor gene. In this study we have determined that the NBCCS gene is also linked to this region in Australasian pedigrees and that there is no significant evidence of heterogeneity. We have defined the localization of the gene by multipoint and haplotype analysis of 15 families, using four microsatellite markers. LOH at these loci was detected in 50% of sporadic BCCs, a rate that is significantly higher than that in other skin lesions used as controls.

Blepharophimosis, ptosis, epicanthus inversus syndrome (BPES syndrome)

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Systemic Haemophilus influenzae infection in childhood

Forty-nine children who had systemic Haemophilus infection and were treated at the Westmead Centre, Sydney, over a two-year period are described. The majority (29 of 49 children) were aged two years or less. Epiglottis and meningitis accounted for 77% of these infections. All H. influenzae isolates associated with clinical disease were of the capsular type b. Eight per cent (four of 50) of H. influenzae infections were caused by beta-lactamase producing strains. There was no geographic clustering or seasonal variation. There was no mortality. Major morbidity included two patients who had epiglottis and required tracheostomy, and two patients who had meningitis developed bilateral profound sensorineural deafness. No secondary cases were detected in household contacts of 21 patients with H. influenzae meningitis during the study period. Epiglottis frequently occurs in very young children. The rapid response to antibiotic treatment suggests that early cases of epiglottis may be undiagnosed, but treated with antibiotic agents in the community.