A new highly penetrant form of obesity due to deletions on chromosome 16p11.2.

Obesity has become a major worldwide challenge to public health, owing to an interaction between the Western 'obesogenic' environment and a strong genetic contribution. Recent extensive genome-wide association studies (GWASs) have identified numerous single nucleotide polymorphisms associated with obesity, but these loci together account for only a small fraction of the known heritable component. Thus, the 'common disease, common variant' hypothesis is increasingly coming under challenge. Here we report a highly penetrant form of obesity, initially observed in 31 subjects who were heterozygous for deletions of at least 593 kilobases at 16p11.2 and whose ascertainment included cognitive deficits. Nineteen similar deletions were identified from GWAS data in 16,053 individuals from eight European cohorts. These deletions were absent from healthy non-obese controls and accounted for 0.7% of our morbid obesity cases (body mass index (BMI) >or= 40 kg m(-2) or BMI standard deviation score >or= 4; P = 6.4 x 10(-8), odds ratio 43.0), demonstrating the potential importance in common disease of rare variants with strong effects. This highlights a promising strategy for identifying missing heritability in obesity and other complex traits: cohorts with extreme phenotypes are likely to be enriched for rare variants, thereby improving power for their discovery. Subsequent analysis of the loci so identified may well reveal additional rare variants that further contribute to the missing heritability, as recently reported for SIM1 (ref. 3). The most productive approach may therefore be to combine the 'power of the extreme' in small, well-phenotyped cohorts, with targeted follow-up in case-control and population cohorts.

Gross rearrangements of the MECP2 gene are found in both classical and atypical Rett syndrome patients.

MECP2 mutations are identifiable in approximately 80% of classic Rett syndrome (RTT), but less frequently in atypical RTT. We recruited 110 patients who fulfilled the diagnostic criteria for Rett syndrome and were referred to Cardiff for molecular analysis, but in whom an MECP2 mutation was not identifiable. Dosage analysis of MECP2 was carried out using multiplex ligation dependent probe amplification or quantitative fluorescent PCR. Large deletions were identified in 37.8% (14/37) of classic and 7.5% (4/53) of atypical RTT patients. Most large deletions contained a breakpoint in the deletion prone region of exon 4. The clinical phenotype was ascertained in all 18 of the deleted cases and in four further cases with large deletions identified in Goettingen. Five patients with large deletions had additional congenital anomalies, which was significantly more than in RTT patients with other MECP2 mutations (2/193; p<0.0001). Quantitative analysis should be included in molecular diagnostic strategies in both classic and atypical RTT.

Anderson-Fabry disease: clinical manifestations and impact of disease in a cohort of 98 hemizygous males.

OBJECTIVES: To determine the natural history of Anderson-Fabry disease (AFD) as a baseline for efficacy assessment of potentially therapeutic drugs. DESIGN: The first large cross sectional study of a patient cohort from the AFD clinical and genetic register (UK), maintained for the last 15 years. MEASURES: Prevalence, mortality, frequency of AFD manifestations, and impact of disease on patient lives, assessed from the AFD register and the disease specific questionnaire. RESULTS: The median cumulative survival was 50 years (n=51), which represents an approximately 20 year reduction of life span. Neuropathic pain was present in 77% (n=93) with mean pain score of 5 (scale 0-10) despite treatment with anticonvulsants and opiates. Pain stopped in only 11%. Cerebrovascular complications developed in 24.2% and renal failure in 30%. The onset and progression of serious AFD manifestations was highly variable. The relationship of gastrointestinal manifestations on weight, using body mass index (BMI), was significant (p=0.01). High frequency sensorineural deafness was confirmed in 78% of audiograms. Neuropathic pain and angiokeratoma were absent in five adult males (approximately 5%). Median age at diagnosis of AFD was 21.9 years (n=64). IMPACT OF DISEASE: Attendance at school, sports, and social activity were significantly affected by AFD. Only 56.6% (n=46) of patients were employed. Psychosexual effects of genital angiokeratoma, genital pain, and impotence were not previously recognised. CONCLUSION: The majority of males experience multiple disease manifestations and the duration of neuropathic pain was lifelong. The AFD register proved useful for the determination of baseline disease parameters in this cohort.

Attempts at use of strychnine sulfate in the treatment of nonketotic hyperglycinemia.

In two cases of nonketotic hyperglycinemia treated from early ages with strychnine sulphate, the patients demonstrated persistent severe psychomotor retardation and seizures. Strychnine therapy improved tone and feeding, but did not seem to alter fundamentally the course of the disease in either patient.

Radial ray defect and Duane anomaly: report of a family with autosomal dominant transmission.

We report on a family in which a mother and her 2 offspring presented with bilateral radial defects and absent thumbs. In addition, Duane anomaly was present in both offspring, one of whom also had anal stenosis. Clinical investigation showed no skeletal, cardiac, or urogenital abnormalities. Autosomal dominant transmission of radial defects is suggested, with Duane anomaly and anal stenosis representing manifestations of the same gene.

Two brothers with facial anomalies, microcephaly, hypoplastic genitalia, and a failure of psychomotor development.

We report on 2 brothers from a consanguineous Moslem family with prenatal onset of growth deficiency, microcephaly, hypoplastic genitalia, and convulsions from birth. Phenotypic anomalies consisted of a prominent glabella, arched eyebrows, a low upswept frontal hairline, a small pinched nose, large posteriorly rotated ears with overfolded upper helices, partial camptodactyly, and widespaced nipples. Psychomotor development was absent, and there was marked failure to thrive. Death occurred at ages 21 days and 7 months, respectively. Postmortem examination on one child showed dilated cerebral ventricles and hydronephrosis. Microcephaly was detectable by fetal ultrasound in one brother at 17 weeks of gestation.

Sparse hair, short stature, hypoplastic thumbs, single upper central incisor and abnormal skin pigmentation: a possible "new" form of ectodermal dysplasia.

A family is described where a mother and three sons have an unusual form of ectodermal dysplasia that may have been described in the medical literature only once before. The unusual manifestations in this family are mild short stature, sparse scalp hair, skin pigmentation and a transient urticarial-like reaction on the hands and arms. The mother and one son demonstrated a single, upper central incisor and the mother and another son had hypoplastic thumbs. The mother alone had hyperkeratosis of the palms and soles. The inheritance pattern is most likely autosomal dominant, although X-linked dominant inheritance cannot be excluded.

Neuropathic pain in Anderson-Fabry disease: pathology and therapeutic options.

An inherited deficiency of the enzyme alpha-galactosidase A is manifest clinically as Anderson-Fabry disease. Most affected patients present with severe peripheral pain in childhood or early adult life, and frequently progress to multi-organ failure by the 4th or 5th decades. The present review examines the probable mechanisms that contribute to pain in these patients, and outlines some of the treatment options that are currently used. The successful outcome of the first two trials of enzyme replacement therapy suggest that this disease might be amenable in the future to gene therapy.

Gene therapy: panacea or placebo? I. Strategies and limitations of gene therapy.

Progress in genetics and molecular medicine has led to characterization of many disorders at the level of specific genes. Techniques for reliable diagnosis of these disorders have been developed in parallel. Attempts are currently being made to develop DNA-based therapeutic procedures to correct genetic diseases. These procedures are known under a common name of gene therapy. The initial step in gene therapy is the delivery of the gene of interest into target cells. There are several conceptually different approaches to achieve this, e.g. targeting can be accomplished by using viral vectors (transduction) or DNA-mediated routes (transformation) either ex vivo or in vivo. The selection of vector systems and the choice of delivering genes either into isolated cells or directly in the organism depend on factors like: the nature of target cell or organ, the levels of expression required, stability and/or regulation of expression, safety, etc. Many viruses have been adapted for use as vectors for gene therapy, according to their specific properties. Viral genomes have been modified to remove their ability to replicate and to increase the cloning capacity. Non-viral gene delivery systems rely on cellular mechanisms to import DNA into the cell nucleus and different methods to enhance DNA uptake have been attempted. Despire many significant achievements there are still obstacles to the development of effective clinical products. Most significant are the low levels and stability of expression of introduced genes and immune responses to vectors and/or gene products.

Gene therapy: panacea or placebo? II. Main applications of gene therapy.

For most disorders the ideal goal of gene therapy is the repair of the mutated gene in the target tissue. However, the techniques required for such an approach are still at an early stage of development. Most current research is directed towards delivery of normal gene sequences in order to generate active protein and compensate for the lack of endogenous production. This approach may be suitable for the treatment of recessive monogenic disorders, but is inappropriate for dominantly inherited disorders. Therefore, gene therapy was originally intended as a most promising approach for the treatment of inborn errors of metabolism. However, apart from the correction of heritable genetic disorders, gene delivery has many potential applications including treatment of malignancies, atherosclerosis and vascular proliferative disorders, rheumatoid arthritis and viral infections. The authors discuss significant examples marking progress in the development of gene therapy for specific diseases, present some hopes and hurdles that have arisen from some recent preclinical and early clinical trials.

Hearing improvement in patients with Fabry disease treated with agalsidase alfa.

AIM: To describe the nature and prevalence of hearing loss in Fabry disease, and its response to enzyme replacement therapy (ERT) with agalsidase alfa. METHODS: Fifteen male patients with Fabry disease were enrolled in a randomized, double-blind study and received placebo (n = 8) or ERT (n = 7) with agalsidase alfa for 6 months. This was followed by an open-label extension of 36 months thus far. Alongside this trial, an additional eight men and two women have so far received open-label ERT for between 6 and 30 months. Pure-tone audiometry, impedance audiometry and otoacoustic emission testing were performed at 0 (baseline), 6, 18, 30 and 42 months. RESULTS: Nine patients (36%) had bilateral and ten (40%) had unilateral high-frequency sensorineural hearing loss (SNHL). Three (12%) had unilateral middle ear effusions with conductive losses persisting beyond 6 months. Only five patients (20%) had normal hearing. The high-frequency SNHL deteriorated over the first 6 months in both placebo and active treatment groups by a median 6.3 dB (p < 0.0001, Wilcoxon matched-pairs). This hearing loss subsequently improved above baseline by 1.5 dB at 18 months (p = 0.07), by 5.0 dB at 30 months (p = 0.006) and by 4.0 dB at 42 months (p = 0.01). CONCLUSION: Significant hearing loss, usually high-frequency SNHL, is a common manifestation of Fabry disease in adults. Alpha-galactosidase A replacement therapy with agalsidase alfa appears to reverse the hearing deterioration in these patients. This improvement, however, is gradual, suggesting the need for long-term ERT.

Female with hypohidrotic ectodermal dysplasia and de novo (X;9) translocation. Clinical documentation of the AnLy cell line case.

We present here a historical documentation of a female with X-linked hypohidrotic ectodermal dysplasia (XHED) and a de novo X/9 chromosome translocation. The patient was verbally reported by Dr. P.L. J. Cook to the HGM conference in 1973, but was subsequently lost to follow up. We have since traced her and confirmed the diagnosis of XHED with moderately severe mental retardation. According to Dr. P. L. J. Cook's records, fibroblast cell line AnLy GMO 705, was derived from this patient. Another female with a de novo X/12 chromosome translocation and hypohidrotic ectodermal dysplasia was recently reported. In both cases, the X chromosome breakpoint appears to be at Xq13.1.

Autosomal recessive hereditary motor and sensory neuropathy with mental retardation, optic atrophy and pyramidal signs.

A syndrome is described, consisting of severe neurogenic distal wasting, generalised muscle weakness, absent ankle reflexes, pyramidal signs, mental retardation, optic atrophy and retinal colloid bodies. A sural nerve biopsy from one case showed loss of nerve fibres suggesting the diagnosis of hereditary motor and sensory neuropathy. Progression of the disorder was very slow, all patients still being able to walk more than 20 years after the onset. The persons affected with this syndrome were two brothers and their female cousin from a large Gujerati pedigree where consanguinity was high. Autosomal recessive inheritance is therefore suggested.

Gene localisation of X-linked hypohidrotic ectodermal dysplasia (C-S-T syndrome).

Genetic linkage studies were carried out in families with X-linked hypohidrotic ectodermal dysplasia (C-S-T syndrome). A DNA probe DXYS1 (pDP34), which maps both to the proximal part of the long arm of the X chromosome, Xq13-Xq21, and proximally on Yp, was used to detect a TaqI restriction fragment length polymorphism of the X-chromosomal locus in the DNA samples from 11 families. This locus was found to be closely linked to the X-linked hypohidrotic ectodermal dysplasia locus, with a lod score of 2.66 at recombination fraction (theta) of 0.06 (90% confidence limits 0.01-0.26). Only one crossover was observed in nineteen meioses. This indicates that the probe DXYS1 is closely linked to the X-linked hypohidrotic ectodermal dysplasia locus and is likely to facilitate carrier detection and prenatal diagnosis tests.

The rate of purine synthesis de nova in blood mononuclear cells in vitro from patients with familial hyperuricaemic nephropathy.

We have measured the rate of purine synthesis de novo in blood mononuclear cells in vitro and the activities of the purine salvage enzymes [hypoxanthine phosphoribosyltransferase (HPRT; EC 2.4.2.8), adenine phosphoribosyltransferase (APRT; EC 2.4.2.7)] and ribosephosphate pyrophosphokinase (PP-ribose-P synthetase; EC 2.7.6.1)] and the concentration of phosphoribosylpyrophosphate (PP-ribose-P) in the erythrocytes of affected family members. These subjects belong to families where hyperuricaemia and renal failure occur together early in life, and the genetic transmission follows an autosomal dominant mode of inheritance. We term this syndrome, familial hyperuricaemic nephropathy. No significant differences were detected in either the rates of purine synthesis de novo in vitro between the index patients and the control subjects with respect to the enzyme activities or the PP-ribose-P concentrations. Two groups of controls were used, healthy individuals and patients with a comparable degree of renal failure due to non-immune complex renal disease. Mononuclear cells from patients with Lesch-Nyhan syndrome (congenital HPRT deficiency) showed the expected acceleration of purine synthesis de novo in vitro. The accelerated purine synthesis de novo in vitro associated with phytohaemagglutinin-induced lymphocyte transformation was detectable by the method used. We conclude that familial hyperuricaemic nephropathy is not due to a metabolic lesion which causes accelerated purine synthesis de novo. This suggests that the primary abnormality may be a failure of the renal tubular net excretion of urate.

Osteopenia, abnormal dentition, hydrops fetalis and communicating hydrocephalus.

We describe a single male infant who developed severe hydrops fetalis between 19 and 28 weeks of gestation. After delivery at 32 weeks he was treated by hemofiltration, prolonged ventilation and intravenous feeding. He had hypertelorism, orbital hypoplasia without proptosis, brachydactyly, frontal and temporal bossing of the skull, central hypotonia, communicating hydrocephalus, and severe delay in psychomotor development. Signs of connective tissue disorder included: osteopenia, pathological fracture, yellow/grey discolored teeth, blue sclerae and easy bruising. Laboratory investigations failed to reveal the cause of fetal hydrops or collagen abnormality. His mother and one sib had learning difficulties. Although some of these findings may be due to perinatal factors, the connective tissue abnormalities suggest a genetic syndrome in the heterogeneous group of osteogenesis imperfecta. This case either represents the more severe end of the spectrum of Type IV osteogenesis imperfecta or the mild end of the spectrum of Cole-Carpenter syndrome.

Identification of functioning sweat pores and visualization of skin temperature patterns in X-linked hypohidrotic ectodermal dysplasia by whole body thermography.

In this preliminary study, non-invasive infrared thermography has been used to visualize individual sweat pores and whole body skin temperature patterns in subjects with X-linked hypohidrotic ectodermal dysplasia (XHED) and normal controls. The findings in eight obligate heterozygotes and four affected males were compared to six normal female controls and to six non-manifesting females at risk for carrier status. Sweat secretion from individual pores in circumscribed areas was imaged using a high spatial resolution SPRITE infrared detector system working in the 8-14 microns band. In seven out of eight obligate heterozygotes, skin areas devoid of active sweat glands were found on the face, the hands or the trunk. Tear front movement over the cornea was also visualized and abnormal patterns were identified in obligate heterozygotes. Whole body skin temperature patterns, obtained with an Agema 780 Medical Thermovision system, identified abnormal skin temperature distributions, including characteristic aberrant "cascade" back patterns, in obligate carriers. Two out of six "at risk" females had skin temperature patterns comparable with obligate heterozygotes and we have tentatively concluded that they are carriers. Thermal imaging may be used for the examination of "at risk" non-manifesting females in families with a single affected male. The results of this study suggest that the random X-inactivation in females with XHED, as well as producing relatively large skin areas with sweat pore aplasia, is also associated with abnormal temperature patterns that are consistent with altered peripheral vascular perfusion.

Epiphyseal dysplasia of the femoral head, mild vertebral abnormality, myopia, and sensorineural deafness: report of a pedigree with autosomal dominant inheritance.

A family is presented with short stature, femoral epiphyseal dysplasia, mild vertebral changes, and sensorineural deafness inherited as an autosomal dominant trait. Myopia and retinal detachment presenting in adult life were also present in some affected members. We suggest that this disorder may be a distinct entity within the spondyloepiphyseal dysplasia group of disorders.