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.

Pseudoaneurysm of the peroneal artery: presentation of Ehlers-Danlos syndrome type IV.

INTRODUCTION: Pseudoaneurysms in deep or unusual sites raise the possibility of an underlying vessel wall disorder. REPORT: A 28-year-old woman presented with pain and swelling of her calf, with no history of trauma. Angiography diagnosed a peroneal artery pseudoaneurysm, which we embolised successfully. Subsequent genetic analysis revealed the COL3A1 mutation, confirming Ehlers-Danlos syndrome type IV. CONCLUSION: To our knowledge, this is the first report of a peroneal artery pseudoaneurysm associated with underlying collagen vascular disease.

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.

Fabry disease: fourteen alpha-galactosidase A mutations in unrelated families from the United Kingdom and other European countries.

The nature of the molecular lesions in the alpha-galactosidase A gene causing Fabry disease in 12 unrelated families from the United Kingdom and 4 from other European countries was determined in order to provide precise heterozygote detection and prenatal diagnosis for these families. The entire alpha-galactosidase A coding region and flanking intronic sequences were analyzed by amplification of genomic DNA and solid-phase direct sequencing or by SSCP analysis followed by solid-phase direct sequencing. Fourteen new mutations were identified including 10 missense mutations (M42V, R49S, C56Y, D92H, D93G, P205T, W236C, W287G, N298H, and W340R), 2 nonsense mutations (Q107X and Q119X) and 2 small deletions (257del18 and 1087del1). Together with the previously reported mutations, a total of 33 lesions in the alpha-galactosidase A gene have been identified in unrelated British families, further documenting the molecular genetic heterogeneity of this disease.

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.

The reliability of immunohistochemistry as a prescreening method for the diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC)--results of an international collaborative study.

Hereditary nonpolyposis colorectal cancer syndrome (HNPCC) is an autosomal dominant condition accounting for 2-5% of all colorectal carcinomas as well as a small subset of endometrial, upper urinary tract and other gastrointestinal cancers. An assay to detect the underlying defect in HNPCC, inactivation of a DNA mismatch repair enzyme, would be useful in identifying HNPCC probands. Monoclonal antibodies against hMLH1 and hMSH2, two DNA mismatch repair proteins which account for most HNPCC cancers, are commercially available. This study sought to investigate the potential utility of these antibodies in determining the expression status of these proteins in paraffin-embedded formalin-fixed tissue and to identify key technical protocol components associated with successful staining. A set of 20 colorectal carcinoma cases of known hMLH1 and hMSH2 mutation and expression status underwent immunoperoxidase staining at multiple institutions, each of which used their own technical protocol. Staining for hMSH2 was successful in most laboratories while staining for hMLH1 proved problematic in multiple labs. However, a significant minority of laboratories demonstrated excellent results including high discriminatory power with both monoclonal antibodies. These laboratories appropriately identified hMLH1 or hMSH2 inactivation with high sensitivity and specificity. The key protocol point associated with successful staining was an antigen retrieval step involving heat treatment and either EDTA or citrate buffer. This study demonstrates the potential utility of immunohistochemistry in detecting HNPCC probands and identifies key technical components for successful staining.

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.

Acrorenal syndrome: further observations.

A 23-year-old female patient with the acrorenal syndrome is described. In addition to acral and renal malformations, she had anomalies of the gastrointestinal and genital tracts. An annular pancreas had caused duodenal obstruction and had been associated with malrotation of the bowel. Secondary sexual characteristics were absent; no ovaries were identified by pelvic ultrasound, and endocrine investigations were compatible with non-functioning ovaries.

Microcephaly, focal segmental glomerulonephritis and marfanoid habitus in two sibs.

Two female sibs aged 15 and 18 years with microcephaly, mental retardation and marfanoid habitus who developed focal segmental glomerulonephritis leading to renal failure are described. This combination of features appears to represent a unique syndrome distinct from previous reports of microcephaly in association with the nephrotic syndrome. The mode of inheritance is likely to be autosomal recessive.

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.