SAM syndrome is characterized by extensive phenotypic heterogeneity.

Severe skin dermatitis, multiple allergies and metabolic wasting (SAM) syndrome is a rare life-threatening inherited condition caused by bi-allelic mutations in DSG1 encoding desmoglein 1. The disease was initially reported to manifest with severe erythroderma, failure to thrive, atopic manifestations, recurrent infections, hypotrichosis and palmoplantar keratoderma. We present 3 new cases of SAM syndrome in 2 families and review the cases published so far. Whole exome and direct sequencing were used to identify SAM syndrome-causing mutations. Consistent with previous data, SAM syndrome was found in all 3 patients to result from homozygous mutations in DSG1 predicted to result in premature termination of translation. In contrast, as compared with patients previously reported, the present cases were found to display a wide range of clinical presentations of variable degrees of severity. The present data emphasize the fact that SAM syndrome is characterized by extensive phenotypic heterogeneity, suggesting the existence of potent modifier traits.

Treatment outcome of acne vulgaris with oral isotretinoin.

OBJECTIVE: To determine the clinical efficacy of oral isotretinoin in the treatment of severe acne and assess its effect on total serum cholesterol, triglycerides, HDL-cholesterol and Low-Density Lipoprotein-cholesterol (LDL-cholesterol). STUDY DESIGN: A cohort, descriptive, hospital-based study. PLACE AND DURATION OF STUDY: Al-Ain Medical District, Tawam Hospital, United Arab Emirates, from 1994 to 2002. METHODOLOGY: A total of 198 patients seen at Tawam Hospital, referred with acne vulgaris for a minimum of 6 weeks, were treated by isotretinoin for the first time, were included in the study. Variables studied were as per objectives apart from demographics and distribution. RESULTS: The study included 63 (32%) males and 135 (68%) females of mean age (+/-SD) of 21.3+/-5.6 years. Majority (81%) of patients was under 25 years. Of them, 26 patients had family history of acne. The most common site of acne was on face (66.7%), followed by trunk (26.2%) and neck (9.1%). Of 198 patients treated, 32.8% were cured, 19.1% markedly improved, 11.1% moderately improved and 24.2% of patients were advised for further treatment. There was no marked change in total and LDL-cholesterol, while LDL and triglycerides changed markedly. CONCLUSION: In acne patients, isotretinoin is effective in producing remission. In addition, it was safe and its effect on serum lipids was transient, especially in healthy and young patients with normal liver functions.

Ichthyosis, follicular atrophoderma, and hypotrichosis caused by mutations in ST14 is associated with impaired profilaggrin processing.

Congenital ichthyosis encompasses a heterogeneous group of disorders of cornification. Isolated forms and syndromic ichthyosis can be differentiated. We have analyzed two consanguineous families from the United Arab Emirates and Turkey with an autosomal recessive syndrome of diffuse congenital ichthyosis, patchy follicular atrophoderma, generalized and diffuse nonscarring hypotrichosis, marked hypohidrosis, and woolly hair (OMIM 602400). By genome-wide analysis, we found a homozygous interval on chromosome 11q24-q25 and obtained a LOD score of 4.0 at D11S910. We identified a homozygous splice-site mutation in the Arab patients and a frame-shift deletion in the Turkish patient in the gene suppression of tumorigenicity-14 (ST14). The product of ST14, matriptase, is a type II transmembrane serine protease synthesized in most human epithelia. Two missense mutations in ST14 were recently described in patients with a phenotype of ichthyosis and hypotrichosis, indicating diverse activities of matriptase in the epidermis and hair follicles. Here we have further demonstrated the loss of matriptase in differentiated patient keratinocytes, reduced proteolytic activation of prostasin, and disturbed processing of profilaggrin. As filaggrin monomers play a pivotal role in epidermal barrier formation, these findings reveal the link between congenital disorders of keratinization and filaggrin processing in the human skin.

Rapid decay of alpha6 integrin caused by a mis-sense mutation in the propeller domain results in severe junctional epidermolysis bullosa with pyloric atresia.

Genetic mutations in alpha6beta4 integrin cause junctional epidermolysis bullosa with pyloric atresia, a genodermatosis characterized by blistering of the skin and pyloric occlusion. The lethal form of junctional epidermolysis bullosa with pyloric atresia has been mainly associated with the presence of premature termination codons in the mRNA encoding either the alpha6 or beta4 subunit causing rapid decay of the mutated transcript and absence of alpha6beta4 integrin. In this study, we disclose the genetic background of lethal junctional epidermolysis bullosa with pyloric atresia in a patient presenting absent expression of alpha6 integrin despite normal steady-state level of the alpha6beta4 mRNA. Screening for mutation in the alpha6 gene detected a homozygous base pair substitution (286 C-to-T), which results in the substitution of a serine with a leucine residue (S47L). The amino acid substitution S47L localizes in the first beta-strand of the seven-bladed beta-propeller structure of the extracellular head of alpha6 integrin, and triggers a rapid proteolysis of the aberrant polypeptides involving the lysosomal degradation pathway. This study provides new insight into the pathogenic effect of a mis-sense mutation affecting a functional domain of a protein, and identifies a critical peptide sequence of the beta-propeller domain conserved among the alpha integrin cell receptors.

Associations between the human insulin gene 5' VNTR and clinical variables of the renin-angiotensin system.

BACKGROUND: Blood pressure regulation is a complex process influenced by numerous environmental and genetic factors. Consequently, there's no cookie-cutter approach for the elucidation of of the genetic mechanism involved. One of the goals of molecular geneticists in the field of hypertension is to unravel the genetic architecture of blood pressure regulation. METHODS: With the aim of identifying quantitative trait loci participating in the control of blood pressure, we carried out a pilot study on a sample population of middle-aged, U.S. Caucasians (44 subjects). The design of the study was to search for associations between clinical variables of blood pressure regulation pertaining to the renin-angiotensin-aldosterone system (systolic and diastolic blood pressures, urinary excretion of sodium, potassium and aldosterone, plasma renin activity) and a genetic marker at a candidate gene locus - the human insulin gene (INS) RESULTS: We observed significant associations between a variable number of tandem repeats (VNTR) marker (visualized as a biallelic, class I/class III marker system) localized at the 5' end of the human INS gene, and plasma renin activity and urinary sodium, potassium and aldosterone. CONCLUSION: Our results indicate that between 6 and 10 QTLs with comparable effects could be involved in blood pressure regulation via the rennin angiotensin system.

Mal de Meleda (MDM) caused by mutations in the gene for SLURP-1 in patients from Germany, Turkey, Palestine, and the United Arab Emirates.

Mal de Meleda (MDM) or keratosis palmoplantaris transgrediens of Siemens is an autosomal recessive skin disorder characterized by diffuse palmoplantar keratoderma (PPK) and transgressive keratosis with an onset in early infancy. There is no associated involvement of other organs; however, a spectrum of clinical presentations with optional and variable features has been described. Mutations in the ARS (component B)-81/s gene ( LY6LS) on chromosome 8q24-qter, which encodes SLURP-1, have recently been identified in patients with MDM. Here, we have analyzed four MDM families for mutations in SLURP-1. In a large Palestinian pedigree with multiple consanguinity, patients are homozygous for a new mutation that substitutes an arginine for a conserved glycine residue at position 86. A different mutation in Turkish patients results in the same amino acid exchange. Some remarkable similarities are seen in the clinical picture of patients from both families. Patients of an Emirati Bedouin family have a homozygous alteration of the translation initiation codon. In a German family with no known consanguinity, we have shown pseudodominant inheritance. Three affected children and their affected mother are homozygous for the missense mutation W15R. Our findings indicate that the MDM type of transgressive PPK is caused by SLURP-1 mutations in patients from various origins and demonstrate allelic heterogeneity for mutations in SLURP-1.

L-2-hydroxyglutaric aciduria in two siblings.

Two Pakistani siblings with L-2-hydroxyglutaric aciduria are reported herein. A 6-year-old male and a 2-year-old female, born to consanguineous parents, had chronic slowly progressive neurodegenerative disorder with insidious onset after infancy. Mental regression and seizures were evident in both patients, whereas cerebellar dysfunction was the main motor handicap in the male and pyramidal symptoms were prominent in the female. Magnetic resonance imaging revealed bilateral symmetrical abnormal signal in the subcortical white matter, internal and external capsules, basal ganglia, and dentate nuclei. The underlying metabolic defect, which is likely inherited in an autosomal recessive mode, remains unknown in this disorder.

Junctional epidermolysis bullosa in the Middle East: clinical and genetic studies in a series of consanguineous families.

BACKGROUND: Junctional epidermolysis bullosa (JEB) is a group of inherited blistering diseases characterized by epidermal-dermal separation resulting from mutations that affect the function of critical components of the basement membrane zone. This group of autosomal recessive diseases is especially prevalent in regions where consanguinity is common, such as the Middle East. However, the clinical and genetic epidemiology of JEB in this region remains largely unexplored. OBJECTIVE: The aim of the present study was to assess a series of consanguineous JEB families originating from the Middle East. METHODS: We identified 7 families referred to us between 1998 and 1999 and originating from the United Arab Emirates, Saudi Arabia, Sudan, Yemen, and Israel. Histologic, immunofluorescence, and electron microscopy studies were performed to direct the subsequent molecular analysis. DNA obtained from all family members was amplified by means of polymerase chain reaction and analyzed by conformation-sensitive gel electrophoresis with subsequent direct sequencing. RESULTS: In 6 families presenting with the clinical and histologic features distinctive for JEB, mutations in genes encoding 1 of the 3 subunit polypeptides of laminin-5 were identified. Two families each had mutations in LAMB3, 2 in LAMA3, and 2 in LAMC2. Out of 7 distinct mutations, 5 were novel and 2 were recurrent. No relationship was found between the presence of nonsense/frameshift mutations in laminin-5 genes and perinatal mortality, contradicting a major genotype-phenotype correlation previously reported in the European and US literature. Similarly, none of the recurrent LAMB3 hot spot mutations previously described in other populations was found in our series. Finally, in a family with the clinical diagnosis of generalized atrophic benign epidermolysis bullosa, a homozygous non-sense mutation in Col17A1 gene (encoding the BPAG2 antigen) was identified. CONCLUSION: The present report suggests (1) the existence of a unique spectrum of mutations in the Middle East populations and (2) the need for the implementation of a diagnostic strategy tailored to the genetic features of JEB in this region.