Fine mapping of the neurally expressed gene SOX14 to human 3q23, relative to three congenital diseases.

Members of the Sox gene family encode transcription factors that have diverse and important functions during development. We have recently described the cloning of chick and mouse Sox14 and the expression of these genes in a population of ventral interneurons in the embryonic spinal cord. We report here the cloning and sequencing of the human orthologue of Sox14. Human SOX14 shows remarkable sequence conservation compared with orthologues from other vertebrate species and probably mirrors the expression of these genes in the developing brain and spinal cord. Using radiation hybrid mapping and fluorescence in situ hybridisation, we have localised SOX14 close to the sequence tagged site D3S1576 on human chromosome 3q23. Three congenital disorders have been localised to this region: blepharophimosis-ptosis-epicanthus inversus syndrome (BPES), Charcot-Marie-Tooth neuropathy type IIB (CMT2B) and Mobius syndrome type 2 (MBS2). We have found that SOX14 is unlikely to be involved in any of these disorders because of the position of SOX14 proximal to a BPES breakpoint and the lack of SOX14 coding region alterations in BPES, CMT2B and MBS2 patients.

A FISH approach to defining the extent and possible clinical significance of deletions at the WAGR locus.

Nineteen patients were analysed by fluorescence in situ hybridisation (FISH) with selected 11p13 markers. They were examined because they had either isolated sporadic or familial aniridia, or aniridia with one or more of the WAGR (Wilms' tumour, aniridia, genital anomalies, and mental retardation) syndrome anomalies. The FISH markers from distal 11p13 were cosmids FO2121, PAX6 (aniridia), D11S324, and WT1 (Wilms' tumour predisposition). Two of the patients with isolated aniridia were abnormal, one with an apparently balanced reciprocal 7;11 translocation and an 11p13 breakpoint, which by FISH was shown to be approximately 30 kb distal to the aniridia (PAX6) gene, and the other had a submicroscopic deletion involving part of PAX6 that extended distally for approximately 245 kb. Two patients with aniridia together with other WAGR malformations had deletions involving all four cosmids. One case with aniridia associated with developmental and growth delay had a deletion including FO2121 and PAX6 but not D11S324 and WT1, while in a further case the deletion included all four test cosmids. These studies show that a combined conventional and molecular cytogenetic approach to patients presenting with aniridia is a useful method for differentiating between those with deletions extending into and including WT1 and therefore between those with high and low risks of developing Wilms' tumour.

FISH studies in a patient with sporadic aniridia and t(7;11) (q31.2;p13).

A 2 year old female presenting with bilateral sporadic aniridia was found to have an apparently balanced reciprocal translocation with a chromosome 11 breakpoint within band p13. Fluorescence in situ hybridisation (FISH) studies with distal 11p13 specific cosmids showed that the chromosome 11 breakpoint lay between the aniridia (PAX6) locus and a region approximately 100 kb distal to PAX6 defined by the cosmid FO2121. Although this patient did not have a detectable deletion within PAX6, her aniridia may have resulted from a disruption of the distal chromatin domain containing either enhancers or regulators for PAX6. This case may therefore be another example of aniridia caused by a position effect as recently described in two familial aniridia patients in which the phenotype cosegregated with chromosome abnormalities with 11p13 breakpoints.

Brachydactyly and mental retardation: an Albright hereditary osteodystrophy-like syndrome localized to 2q37.

We report five patients with a combination of brachymetaphalangia and mental retardation, similar to that observed in Albright hereditary osteodystrophy (AHO). Four patients had cytogenetically visible de novo deletions of chromosome 2q37. The fifth patient was cytogenetically normal and had normal bioactivity of the alpha subunit of Gs (Gs alpha), the protein that is defective in AHO. In this patient, we have used a combination of highly polymorphic molecular markers and FISH to demonstrate a microdeletion at 2q37. The common region of deletion overlap involves the most telomeric 2q marker, D2S125, and extends proximally for a maximum distance of 17.6 cM. We suggest this represents a consistent phenotype associated with some deletions at 2q37 and that genes important for skeletal and neurodevelopment lie within this region. Screening for deletions at this locus should be considered in individuals with brachymetaphalangia and mental retardation. Furthermore, 2q37 represents a candidate region for type E brachydactyly.

Clinical identification of a human equivalent to the short ear (se) murine phenotype.

Mutations in the BMP-5 gene at the mouse short-ear locus alter size, shape, and number of many different skeletal elements, and greatly reduce the size of the external ear. The alterations in short-ear mice are confined to particular skeletal features and a human equivalent is not known. We report on 5 patients whose features fit into the clinical criteria of the EPS (ear, patella, short stature) syndrome characterized by very short external ears, small jaw, growth retardation, and different skeletal abnormalities including absent patellae. We postulate on clinical data and phenotype comparisons that some EPS cases might be a human equivalent to the short ear murine disorder.

Evidence for locus heterogeneity in autosomal dominant torsion dystonia.

Idiopathic torsion dystonia (ITD) is most commonly an autosomal dominant disorder with reduced penetrance and variable expression. A locus on the distal long arm of chromosome 9 has been identified in one large non-Jewish and several Jewish families in the United States. Linkage analysis in a large Australian kindred with ITD, also containing two patients with Wilson's disease, excludes a locus for ITD in chromosome 9q34 or the region of chromosome 13 containing the Wilson disease gene. This study provides evidence for locus heterogeneity in autosomal dominant ITD and also gives additional information on gene order in chromosome 9q.

A YAC contig in Xp21 containing the adrenal hypoplasia congenita and glycerol kinase deficiency genes.

The gene loci for adrenal hypoplasia congenita (AHC) and glycerol kinase deficiency (GK) map in Xp21 distal to Duchenne muscular dystrophy (DMD), and proximal to DXS28 (C7), by analysis of patient deletions. We have constructed a yeast artificial chromosome (YAC) contig encompassing a 1.2 Mb region extending distally from DMD, and containing DXS708 (JC-1), the distal junction clone of a patient with GK and DMD. A pulsed-field gel electrophoresis map of the YAC contig identified 3 potential CpG islands. Whole YAC hybridization identified cosmids both for construction of cosmid contigs, and isolation of single copy probes. Thirteen new single copy probes and DXS28 and DXS708 were hybridized on a panel of patients; the deletion mapping indicates that the YAC contig contains both GK and at least part of AHC, and together with the physical map defines a GK critical region of 50-250 kb. In one AHC patient with a cytogenetically detectable deletion we used the new probes to characterize a complex double deletion. Non-overlapping deletions observed in other unrelated AHC patients indicate that the AHC gene is large, extending over at least 200-500 kb. This mapping provides the basis for the identification of the AHC and GK genes.

A reappraisal of the CHARGE association.

We describe 14 boys and six girls, including monozygotic twins, with the CHARGE association. All of the children had at least four of the seven major features included in the mnemonic CHARGE and all had ear anomalies or deafness or both and either coloboma or choanal atresia or both. All the boys had evidence of hypogonadism. A characteristic facial appearance (unusually shaped ears, unilateral facial palsy, square face, malar flattening, pinched nostrils) was observed in many of our cases. The aetiology remains unknown. All our cases are sporadic.