FRAXA and FRAXE: the results of a five year survey

We report the results of a five year survey of FRAXA and FRAXE mutations among boys aged 5 to 18 with special educational needs (SEN) related to learning disability. We tested their mothers using the X chromosome not transmitted to the son as a control chromosome, and the X chromosome inherited by the son to provide information on stability of transmission. We tested 3738 boys and 2968 mothers and found 20 FRAXA and one FRAXE full mutations among the boys and none among the mothers. This gives an estimated prevalence of full mutations in males of 1 in 5530 for FRAXA and 1 in 23 423 for FRAXE. We found an excess of intermediate and premutation alleles for both FRAXA and FRAXE. For FRAXA this was significant at the 0.001 level but the excess for FRAXE was significant only at the 0.03 level. We conclude that the excess of intermediate and premutation sized alleles for FRAXA may well be a contributing factor to the boys' mental impairment, while that for FRAXE may be a chance finding. We studied approximately 3000 transmissions from mother to son and found five instabilities of FRAXA in the common or intermediate range and three instabilities of FRAXE in the intermediate range. Thus instabilities in trinucleotide repeat size for FRAXA and FRAXE are rare, especially among alleles in the common size range.

Microdeletions in FMR2 may be a significant cause of premature ovarian failure

Genetic causes of premature ovarian failure (POF) include X chromosome deletions and fragile X (FRAXA) premutations. While screening a cohort of women with POF for FRAXA premutations, a more distal trinucleotide repeat, FRAXE, was also tested. We found an unexpected excess of FRAXE alleles with apparently fewer than 11 repeats in the POF group. However, sequence analysis of these alleles showed that the excess was caused by three females who carry cryptic deletions in FMR2, the gene associated with FRAXE. We propose that microdeletions within FMR2 may be a significant cause of premature ovarian failure, being found in 1.5% of women with the condition, and in only 0.04% of the general female population. The deletions may affect transcription of either FMR2 or an adjacent gene.

Peroxisomal disorders: clinical and biochemical studies in 15 children and prenatal diagnosis in 7 families

We describe the main clinical and biochemical findings in 15 patients with peroxisomal disorders, together with the results of 11 prenatal investigations for Zellweger syndrome. The initial laboratory diagnosis depended in most cases on demonstration of elevated very long chain fatty acids in plasma, but follow-up studies using cultured fibroblasts were essential for complete classification. The patient group comprises nine cases of Zellweger syndrome, one of neonatal adrenoleucodystrophy, two of infantile Refsum disease, one of bifunctional protein deficiency, and two of rhizomelic chondrodysplasia punctata. The study illustrates the clinical and biochemical variability of this group of patients and the detailed studies that are required for classification.

Williams syndrome: use of chromosomal microdeletions as a tool to dissect cognitive and physical phenotypes

In Williams syndrome (WS), a deletion of approximately 1.5 Mb on one copy of chromosome 7 causes specific physical, cognitive, and behavioral abnormalities. Molecular dissection of the phenotype may be a route to identification of genes important in human cognition and behavior. Among the genes known to be deleted in WS are ELN (which encodes elastin), LIMK1 (which encodes a protein tyrosine kinase expressed in the developing brain), STX1A (which encodes a component of the synaptic apparatus), and FZD3. Study of patients with deletions or mutations confined to ELN showed that hemizygosity for elastin is responsible for the cardiological features of WS. LIMK1 and STX1A are good candidates for cognitive or behavioral aspects of WS. Here we describe genetic and psychometric testing of patients who have small deletions within the WS critical region. Our results suggest that neither LIMK1 hemizygosity (contrary to a previous report) nor STX1A hemizygosity is likely to contribute to any part of the WS phenotype, and they emphasize the importance of such patients for dissecting subtle but highly penetrant phenotypes.

Hidrotic ectodermal dysplasia of hair, teeth, and nails: case reports and review

We report two families with the Witkop "tooth and nail syndrome". This term is a misnomer, as the hair was mildly involved in the original case reports and in the families reported here.

Population screening at the FRAXA and FRAXE loci: molecular analyses of boys with learning difficulties and their mothers

Preliminary results on a large population-based molecular survey of FRAXA and FRAXE are reported. All boys with unexplained learning difficulties are eligible for inclusion in the study and data are presented on the first 1013 tested. Individuals were tested for the number of trinucleotide repeats at FRAXA and FRAXE and typed for four flanking microsatellite markers. Mothers of 760 boys were tested to determine the stability of the FRAXA and FRAXE repeats during transmission and to provide a population of control chromosomes. The frequency of FRAXA full mutations was 0.5%, which gives a population frequency of 1 in 4994, considerably less than previous reports suggest. No FRAXE full mutations were detected, confirming the rarity of this mutation. In the boys' X chromosomes, we detected one FRAXA premutation with 152 repeats and one putative FRAXE premutation of 87 repeats. No full or premutations were seen in the control chromosomes. A significant excess of intermediate alleles at both FRAXA and FRAXE was detected in the boys' X chromosomes by comparison with the maternal control chromosomes. This suggests that relatively large unmethylated repeats of sizes 41-60 for FRAXA and 31-60 for FRAXE may play some role in mental impairment. No instability was found in transmissions of minimal or common alleles in either FRAXA or FRAXE, but we saw two possible instabilities in transmission of FRAXA and two definite instabilities in transmission of FRAXE among 43 meioses involving intermediate or premutation sized alleles. We found no linkage disequilibrium between FRAXA and FRAXE but did find significant linkage disequilibrium between large alleles at FRAXE and allele 3 at the polymorphic locus DXS1691 situated 5 kb distal to FRAXE.

Mirror hands and feet: a further case of Laurin-Sandrow syndrome

We report a girl with mirror hands and feet and associated groove of the nasal columella. She represents only the sixth reported case of this spectrum of congenital anomalies,first reported by Laurin and Sandrow.

Consumer audit in the NHS

Recent Department of Health publications and initiatives have emphasised the need to make services more responsive to the needs of patients. This article describes the consumer audit process, developed by the College of Health, involving a range of sensitive yet rigorous qualitative research processes to provide feedback from patients and their carers, in a form which is of practical and educational use to clinicians and managers and results in change and development.

Unusual (CGG)n expansion and recombination in a family with fragile X and DiGeorge syndrome

In a fragile X family referred for prenatal diagnosis, the female fetus did not inherit the full fragile X mutation from her mother, but an unexpected expansion within the normal range of CGG repeats from 29 to 39 was observed in the paternal X chromosome. Also, a rare recombination between DXS548 and FRAXAC1 was recorded in the maternal meiosis. Follow up of the neonate confirmed the same DNA genotype as in the CVS, but the child died of DiGeorge syndrome after four days and was subsequently found to carry a microdeletion of chromosome 22 using probe cEO. It is suggested that in this family the deletion of chromosome 22 is likely to be a chance event but the rare recombinant and the fragile X mutation might be causally related.

Cystic fibrosis mutation analysis: report from 22 U.K. regional genetics laboratories

We have collated the results of cystic fibrosis (CF) mutation analysis conducted in 22 laboratories in the United Kingdom. A total of 9,807 CF chromosomes have been analysed, demonstrating 56 different mutations so far observed and accounting for 86% of CF genes in the native Caucasian population of the United Kingdom. delta F508 is the most common at 75.3% of CF mutations (range 56.5-83.7%), followed by G551D (3.08%; range 0.71-7.60%), G542X (1.68%; range 0.85-3.66%), 621 + 1 (G > T) (0.93%; range 0.41-3.16%), 1717-1(G > A) (0.57%; range 0.17-1.14%), 1898 + 1)(G > A) (0.46%), R117H (0.46%), N1303K (0.46%), and R553X (0.46%). The data show a clear geographical variation in the distribution of some of the mutations, most notably a marked regional variation in the distribution of 621 + 1 (G > T) and 1989 + 1(G > A), which are both apparently more frequent in Wales. R560T and R117H appear to be more frequent in Ireland and Scotland, and G551D more frequent in Scotland. In summary, these data illustrate that the mutations present within a particular population need to be defined in order to provide meaningful carrier screening and testing for rare mutations in affected individuals. Furthermore, it is apparent that the ethnic origin of a patient, even within a small country such as the United Kingdom, should be taken into account.

The impact of genetic counselling on females in fragile X families

We report a retrospective study over the period 1981-1992 of the reproductive histories of 27 women, from 21 families, who were known or possible fragile X carriers. Eighteen women had cytogenetic and DNA linkage studies to establish their carrier risk. They subsequently received definitive carrier status information following the cloning of the gene in 1991. The remaining nine women had cytogenetic and mutation studies only. For 11 of the women their carrier risk was modified over the 11 year period. The results suggest that these women at risk of having a son with fragile X have carefully considered their reproductive choices. Three of the six women who were initially sterilised have had, or are awaiting, a reversal of sterilisation following clarification of their carrier status. There were 10 pregnancies to 10 women. Seven of the pregnancies were to women at "high" (40-100%) risk of being a carrier, and in this group only one woman chose to continue the pregnancy without prenatal diagnosis. Three pregnancies were to women at "medium" or "low" (< 39%) risk of being a carrier. None of the three chose prenatal diagnosis and one affected male was born to this group.

Anencephaly with spinal dysraphism, cleft lip and palate and limb reduction defects

We report three unrelated fetuses presenting with anencephaly, spinal dysraphism, cleft lip and palate and limb reduction defects. Review of the literature suggests that this association may be more commonly found than previously recognized and may indicate severe disturbance in early embryogenesis.

Relationship between academic placement and perception of abuse of the voice

Informal polling of public school speech-language pathologists indicated that special education teachers referred more children for disorders of voice than did regular classroom educators. This study evaluated the effect of academic placement (regular or special education settings) upon children's and their teachers' ratings of abuse of the voice. Analysis showed the two groups of teachers' criteria for judging abusive vocal behaviors differed while the children's ratings from each setting did not differ. The special educators appeared to perceive their students' vocal behavior as more abusive possibly due to environmental constraints, training or the social affective interactions of their students.

General practitioners' plans for developments in the inner city: a review by a primary care project

This paper describes part of the work of a development project, working in Tower Hamlets in east London in 1983-87, with the wider remit for facilitating primary care development in the inner city. Thirty-nine of the 43 practices in the district were visited and general practitioners discussed their plans for development and the problems they encountered. The paper presents the results of the discussions and the follow-up work, which explored how further developments could be brought about. It concludes that many general practitioners are considering and introducing a wide range of new developments in their inner city practices. Planning for development of primary care in the inner city should focus more closely at local levels on what practices are already planning and provide more encouragement and practical help than at present.