The CCR5-Delta32 deletion obliterates the CCR5 chemokine and the human immunodeficiency virus (HIV)-1 coreceptor on lymphoid cells, leading to strong resistance against HIV-1 infection and AIDS. A genotype survey of 4,166 individuals revealed a cline of CCR5-Delta32 allele frequencies of 0%-14% across Eurasia, whereas the variant is absent among native African, American Indian, and East Asian ethnic groups. Haplotype analysis of 192 Caucasian chromosomes revealed strong linkage disequilibrium between CCR5 and two microsatellite loci. By use of coalescence theory to interpret modern haplotype genealogy, we estimate the origin of the CCR5-Delta32-containing ancestral haplotype to be approximately 700 years ago, with an estimated range of 275-1,875 years. The geographic cline of CCR5-Delta32 frequencies and its recent emergence are consistent with a historic strong selective event (e.g. , an epidemic of a pathogen that, like HIV-1, utilizes CCR5), driving its frequency upward in ancestral Caucasian populations.

Arterial tortuosity syndrome (ATS) is an autosomal recessive\ud disorder characterized by tortuosity, elongation, stenosis and\ud aneurysm formation in the major arteries owing to disruption\ud of elastic fibers in the medial layer of the arterial wall1.\ud Previously, we used homozygosity mapping to map a candidate\ud locus in a 4.1-Mb region on chromosome 20q13.1 (ref. 2).\ud Here, we narrowed the candidate region to 1.2 Mb containing\ud seven genes. Mutations in one of these genes, SLC2A10,\ud encoding the facilitative glucose transporter GLUT10, were\ud identified in six ATS families. GLUT10 deficiency is associated\ud with upregulation of the TGFb pathway in the arterial wall, a\ud finding also observed in Loeys-Dietz syndrome, in which aortic\ud aneurysms associate with arterial tortuosity3. The identification\ud of a glucose transporter gene responsible for altered arterial\ud morphogenesis is notable in light of the previously suggested\ud link between GLUT10 and type 2 diabetes4,5. Our data\ud could provide new insight on the mechanisms causing\ud microangiopathic changes associated with diabetes and\ud suggest that therapeutic compounds intervening with\ud TGFb signaling represent a new treatment strategy

The inherited osteolyses or 'vanishing bone' syndromes are a group of rare disorders of unknown etiology characterized by destruction and resorption of affected bones. The multicentric osteolyses are notable for interphalangeal joint erosions that mimic severe juvenile rheumatoid arthritis (OMIMs 166300, 259600, 259610 and 277950). We recently described an autosomal recessive form of multicentric osteolysis with carpal and tarsal resorption, crippling arthritic changes, marked osteoporosis, palmar and plantar subcutaneous nodules and distinctive facies in a number of consanguineous Saudi Arabian families. We localized the disease gene to 16q12-21 by using members of these families for a genome-wide search for homozygous-by-descent microsatellite markers. Haplotype analysis narrowed the critical region to a 1.2-cM region that spans the gene encoding MMP-2 (gelatinase A, collagenase type IV; (ref. 3). We detected no MMP2 enzymatic activity in the serum or fibroblasts of affected family members. We identified two family-specific homoallelic MMP2 mutations: R101H and Y244X. The nonsense mutation effects a deletion of the substrate-binding and catalytic sites and the fibronectin type II-like and hemopexin/TIMP2 binding domains. Based on molecular modeling, the missense mutation disrupts hydrogen bond formation within the highly conserved prodomain adjacent to the catalytic zinc ion.

PurposeWe aimed to identify the genetic cause to a clinical syndrome encompassing hypohidrosis, electrolyte imbalance, lacrimal gland dysfunction, ichthyosis, and xerostomia (HELIX syndrome), and to comprehensively delineate the phenotype.MethodsWe performed homozygosity mapping, whole-genome sequencing, gene sequencing, expression studies, functional tests, protein bioinformatics, and histological characterization in two unrelated families with HELIX syndrome.ResultsWe identified biallelic missense mutations (c.386C>T, p.S131L and c.2T>C, p.M1T) in CLDN10B in six patients from two unrelated families. CLDN10B encodes Claudin-10b, an integral tight junction (TJ) membrane-spanning protein expressed in the kidney, skin, and salivary glands. All patients had hypohidrosis, renal loss of NaCl with secondary hyperaldosteronism and hypokalemia, as well as hypolacrymia, ichthyosis, xerostomia, and severe enamel wear. Functional testing revealed that patients had a decreased NaCl absorption in the thick ascending limb of the loop of Henle and a severely decreased secretion of saliva. Both mutations resulted in reduced or absent Claudin-10 at the plasma membrane of epithelial cells.ConclusionCLDN10 mutations cause a dysfunction in TJs in several tissues and, subsequently, abnormalities in renal ion transport, ectodermal gland homeostasis, and epidermal integrity.

The syndrome of congenital hypoparathyroidism, mental retardation, facial dysmorphism and extreme growth failure (HRD or Sanjad-Sakati syndrome; OMIM 241410) is an autosomal recessive disorder reported almost exclusively in Middle Eastern populations. A similar syndrome with the additional features of osteosclerosis and recurrent bacterial infections has been classified as autosomal recessive Kenny-Caffey syndrome (AR-KCS; OMIM 244460). Both traits have previously been mapped to chromosome 1q43-44 (refs 5,6) and, despite the observed clinical variability, share an ancestral haplotype, suggesting a common founder mutation. We describe refinement of the critical region to an interval of roughly 230 kb and identification of deletion and truncation mutations of TBCE in affected individuals. The gene TBCE encodes one of several chaperone proteins required for the proper folding of alpha-tubulin subunits and the formation of alpha-beta-tubulin heterodimers. Analysis of diseased fibroblasts and lymphoblastoid cells showed lower microtubule density at the microtubule-organizing center (MTOC) and perturbed microtubule polarity in diseased cells. Immunofluorescence and ultrastructural studies showed disturbances in subcellular organelles that require microtubules for membrane trafficking, such as the Golgi and late endosomal compartments. These findings demonstrate that HRD and AR-KCS are chaperone diseases caused by a genetic defect in the tubulin assembly pathway, and establish a potential connection between tubulin physiology and the development of the parathyroid.

Novel Arab-specific mutations were identified in the CFTR gene underlying cystic fibrosis. As a result of this study, the CFTR mutation detection rate among Arabs with cystic fibrosis is now comparable to that of other populations.

Genes control biological processes such as muscle, cartilage and bone formation, muscle energy production and metabolism (mitochondriogenesis, lactic acid removal), blood and tissue oxygenation (erythropoiesis, angiogenesis, vasodilatation), all essential in sport and athletic performance. DNA sequence variations in such genes confer genetic advantages that can be exploited, or genetic 'barriers' that could be overcome to achieve optimal athletic performance. Predictive Genomic DNA Profiling for athletic performance reveals genetic variations that may be associated with better suitability for endurance, strength and speed sports, vulnerability to sports-related injuries and individualized nutritional requirements. Knowledge of genetic 'suitability' in respect to endurance capacity or strength and speed would lead to appropriate sport and athletic activity selection. Knowledge of genetic advantages and barriers would 'direct' an individualized training program, nutritional plan and nutritional supplementation to achieving optimal performance, overcoming 'barriers' that results from intense exercise and pressure under competition with minimum waste of time and energy and avoidance of health risks (hypertension, cardiovascular disease, inflammation, and musculoskeletal injuries) related to exercise, training and competition. Predictive Genomics DNA profiling for Athletics and Sports performance is developing into a tool for athletic activity and sport selection and for the formulation of individualized and personalized training and nutritional programs to optimize health and performance for the athlete. Human DNA sequences are patentable in some countries, while in others DNA testing methodologies [unless proprietary], are non patentable. On the other hand, gene and variant selection, genotype interpretation and the risk and suitability assigning algorithms based on the specific Genomic variants used are amenable to patent protection.

A descriptive study was undertaken to characterize the cystic fibrosis transmembrane regulator gene mutations (CFTR) in the Saudi Arabian cystic fibrosis (CF) population in relation to clinical presentation and demographic and ethnic origin. During the period October 1992 to September 1997, 70 patients from 46 families were diagnosed as having CF, based on a typical clinical picture and sweat chloride levels > 60 mmol/l and were screened for CFTR mutations. Twelve mutations were identified in 34 families, which constitutes 70% of the CF alleles in the study group. Pancreatic insufficiency (PI) was found in the following mutations: 1548delG in exon 10 (15%) which occurred mainly in native Saudi patients in the central province; 3120 + 1G-->A in intron 16 (10%) and H139L in exon 4 (7%), found mainly in native Saudis from the eastern province; delta F508 mutation (13%) which occurred mainly in expatriates of Middle Eastern origin from different provinces; L117X in exon 19 (2%); G115X in exon 4 (2%); 711 + 1G-->A in intron 5 (2%); N 1303K in exon 21 (2%) and 425del42 in exon 4 (1%); I1234V in exon 19 (13%) with a predominance of nasal polyps and a variable degree of PI and lung disease; R553X in exon 11 (1%), with electrolyte imbalance; and S549R in 11 (2%) with pancreatic sufficiency and minimal pulmonary disease. The clinical picture did not differ significantly between patients of different ethnic origins with the same CFTR mutation.