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Idiopathic congenital nystagmus is characterized by involuntary, periodic, predominantly horizontal oscillations of both eyes. We identified 22 mutations in FRMD7 in 26 families with X-linked idiopathic congenital nystagmus. Screening of 42 singleton cases of idiopathic congenital nystagmus (28 male, 14 females) yielded three mutations (7%). We found restricted expression of FRMD7 in human embryonic brain and developing neural retina, suggesting a specific role in the control of eye movement and gaze stability. Nat Genet

Psoriasis is an inflammatory skin disorder that is inherited as a multifactorial trait. Genetic analyses have repeatedly identified a primary disease susceptibility locus lying within the major histocompatibility complex (MHC), on chromosome 6p21. A small number of non-MHC susceptibility loci have also been identified. These regions tend to overlap with susceptibility intervals for Crohn's disease and atopic dermatitis, suggesting the possibility that genetic variants affecting inflammatory pathways may contribute to the pathogenesis of multiple disorders. Here, we report a genetic analysis of the interleukin 23 receptor gene (IL23R), which was recently identified as a susceptibility determinant for Crohn's disease. We initially examined the results of a whole-genome association scan, carried out on 318 cases and 288 controls. We observed a significant increase of a non-synonymous substitution (p.Arg381Gln) among controls (P = 0.00036). We validated this finding by extending our cohort to include a further 519 cases and 528 controls. In the overall sample, the frequency of the 381Gln allele was 3.6% in cases and 7% in controls, yielding a P value of 0.00014. Next, we examined genetic variation at the IL12RB1, IL23A and IL12B genes, respectively, encoding the second subunit of the IL23R receptor and the two subunits of its ligand. This analysis identified independent associations for IL12B SNPs rs10045431 (P value for the extended dataset = 0.0001) and rs3212227 (P = 0.036). Altogether, these findings indicate that genes participating in IL23 signalling play a significant role in the pathogenesis of chronic epithelial inflammation.

Objective: To investigate the molecular genetic basis of cluster headache (CH), using a genome-wide scan and candidate gene strategy. Methods: Northern European CH families and a case-control cohort of Danish, Swedish, and British origin (total n = 259 sporadic CH patients), including 267 control subjects matched for ancestry, participated in the study. A genome-wide genetic screen using approximately 400 microsatellite markers was performed for five informative Danish CH families. Additional markers were typed for those loci generating statistical evidence suggestive of linkage, together with genotypes for 111 individuals from further Danish and Italian kindreds. Sporadic CH patients and controls were investigated by association analysis for variation in the candidate gene, HCRTR2 . Finally, complete HCRTR2 sequencing was undertaken for eight independent probands. Results: Potential linkage was identified at four possible disease loci in Danish kindreds, yet no single chromosome location generated a lod or NPL score of recognized significance. No deleterious sequence variants of the HCRTR2 gene were detected by comparison to wild-type sequence. Association of the HCRTR2 gene was not replicated in this large dataset, even when the data were stratified into distinct populations. Conclusions: Cluster headache is a complex genetic disorder, with possible phenotypic and genetic heterogeneity compounding attempts at gene identification.

ypoparathyroidism is a heterogeneous group of disorders with both acquired and inherited causes, each presenting clinically with hypocalcaemia. Familial cases of hypoparathyroidism may be due to an isolated defect of the parathyroid glands or be a component of a syndrome disorder, examples of which include DiGeorge, hypoparathyroidism-retardation-dysmorphism, and KennyCaffey syndrome. 1 Familial isolated hypoparathyroidism (FIH) is characterised by hypocalcaemia and hyperphosphataemia and may be due to an inherited deficiency or the abnormal activity of parathyroid hormone (PTH). FIH is heterogeneous with X linked, autosomal dominant, and autosomal recessive modes of inheritance reported. 2 Mutations in the PTH gene on chromosome 11p have been described in both autosomal dominant and autosomal recessive forms of the disorder. 34 Mature PTH is generated by cleavage of the signal peptide from the prepro-PTH, followed by successive proteolysis of pro-PTH within the Golgi apparatus. 5 A requirement for normal PTH processing is emphasised by the detection of FIH disease causing mutations, which include two missense amino acid substitutions within the signal region of the prepro-PTH gene, leading to inefficient cleavage by signal peptidases. 35

Primary open angle glaucoma (POAG) affects 1% of people over age 40. Early detection and treatment can prevent blindness, but the disease is often asymptomatic until a late stage. Positive family history is an important risk factor and previous studies indicate that approximately 5% of POAG results from mutations in the myocilin ( MYOC) gene, raising the possibility of identifying individuals genetically predisposed to glaucoma. We collected DNA samples from 426 unselected UK POAG patients and analyzed them for MYOC mutations. The Q368X mutation was found in six patients (1.4%). No other mutations were identified, suggesting that amongst patients unselected for family history, the prevalence of MYOC mutations in the UK is lower than in other populations. Genetic and glaucoma screening was offered to first-degree relatives of these six probands (group 1) and of age/sex-matched mutation-negative controls (group 2). Of 11 group-1 relatives, three carried Q368X, one of whom already had glaucoma. Notably, of the 13 relatives in both groups who were mutation negative, one was already being treated for ocular hypertension. We therefore caution against changing glaucoma surveillance regimens in such individuals and suggest that routine untargeted genetic testing for MYOC mutations in patients with POAG would be of limited value until additional significant genetic risk factors are identified.

Meckel-Gruber syndrome (MKS), the most common monogenic cause of neural tube defects, is an autosomal recessive disorder characterised by a combination of renal cysts and variably associated features, including developmental anomalies of the central nervous system (typically encephalcoele), hepatic ductal dysplasia and cysts, and polydactyly. Locus heterogeneity has been demonstrated by the mapping of the MKS1 locus to 17q21-24 in Finnish kindreds, and of MKS2 to 11q13 in North African-Middle Eastern cohorts. In the present study, we have investigated the genetic basis of MKS in eight consanguineous kindreds, originating from the Indian sub-continent, that do not show linkage to either MKS1 or MKS2. We report the localisation of a third MKS locus (MKS3) to chromosome 8q24 in this cohort by a genome-wide linkage search using autozygosity mapping. We identified a 26-cM region of autozygosity between D8S586 and D8S1108 with a maximum cumulative two-point LOD score at D8S1179 (Z max=3.04 at θ=0.06). A heterogeneity test provided evidence of one unlinked family. Exclusion of this family from multipoint analysis maximised the cumulative multipoint LOD score at locus D8S1128 (Z max=5.65). Furthermore, a heterozygous SNP in DDEF1, a putative candidate gene, suggested that MKS3 mapped within a 15-cM interval. Comparison of the clinical features of MKS3-linked cases with reports of MKS1- and MKS2-linked kindreds suggests that polydactyly (and possibly encephalocele) appear less common in MKS3-linked families. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/s00439-002-0817-0. On that page (frame on the left side), a link takes you directly to the supplementary material.

Nat. Genet. 38, 1242–1244 (2006); published online 1 October 2006; corrected after print 6 June 2011 In the version of this article initially published, the author Andrew Bastawrous was omitted from the author list. The error has been corrected in the HTML and PDF versions of the article.