We present clinical data on 558 patients with deletions within the DiGeorge syndrome critical region of chromosome 22qll. Twenty-eight percent of the cases where parents had been tested had inherited deletions, with a marked excess of maternally inherited deletions (maternal 61, paternal 18). Eight percent of the patients had died, over half of these within a month ofbirth and the majority within 6 months. All but one of the deaths were the result of congenital heart disease. Clinically significant immunological problems were very uncommon. Nine percent of patients had cleft palate and 32% had velopharyngeal insufficiency, 60% of patients were hypocalcaemic, 75% of patients had cardiac problems, and 36% of patients who had abdominal ultrasound had a renal abnormality. Sixty-two percent of surviving patients were developmentally normal or had only mild learning problems. The majority of patients were constitutionally small, with 36% of patients below the 3rd centile for either height or weight parameters. (JMed Genet 1997;34:798-804) Data collectionParticipating centres from Europe were sent data questionnaires relating to cases of proven deletions within chromosome band 22ql 1. The probes and microsatellite markers used varied between centres but all mapped within the DGS region.2 Centres were asked to send information on all their cases, whether previously published or not. The data for all UK centres was collected by one person (AR) who also entered information into the database from the returned questionnaires. Data were requested on heart, palate, renal, and thymus abnormalities, parathyroid function, growth, developmental status, behaviour, and psychiatric illness. All available patient information was entered into an anonymous central database. Some questionnaires did not provide information on all sections, for example, the heart section was completed in more questionnaires than the renal section. Hence, the total number of patients for which data were recorded is specified in each section of the results.

Genetic mapping studies identified ATR as a candidate gene for Seckel syndrome, but its location on the physical map had not been defined. We used the ATR cDNA sequence to identify a 112-kb genomic sequence 4 that in turn retrieved two linked BACs, one of which was located at 147.77 Mb on chromosome 3, Published online 17 March 2003, doi:10.1038/ng1129 Fig. 1 F02-98 cells show an impaired response to DNA damage. a, F02-98 cells were impaired in phosphorylation of H2AX (γH2AX) and p53 Ser15 induced by ultraviolet radiation (UV) but normal in phosphorylation of these substrates after exposure to ionizing radiation (IR). Owing to difficulty in obtaining sufficient material from primary fibroblast cells for western blotting, the phosphorylation of ATR substrates after exposure to DNAdamaging agents was examined by immunofluorescence using phosphospecific antibodies (α-P-Ser15-p53). Phosphorylation was examined after exposure to ionizing radiation (10 Gy) and ultraviolet radiation (5 J m -2 ) 1 h after irradiation. Cells held under low-serum conditions for 5 d before exposure to ultraviolet radiation had an identical response to that of exponentially growing cells (data not shown). b, F02-98 cells were impaired in phosphorylation of hRad17 and Nbs1 induced by ultraviolet radiation (UV). The examination of phosphorylation was carried out as described in a using phosphospecific antibodies (α-PRad17 and α-P-Nbs1). Immunofluorescence was also analyzed using antibodies that recognize endogenous Rad17 and Nbs1 (α-Rad17 and α-Nbs1; right panels) verifying that these proteins were expressed efficiently before and after ultraviolet radiation treatment in F02-98 cells.

Nephronophthisis (NPHP), an autosomal recessive cystic kidney disease, leads to chronic renal failure in children. The genes mutated in NPHP1 and NPHP4 have been identified, and a gene locus associated with infantile nephronophthisis (NPHP2) was mapped. The kidney phenotype of NPHP2 combines clinical features of NPHP and polycystic kidney disease (PKD). Here, we identify inversin (INVS) as the gene mutated in NPHP2 with and without situs inversus. We show Correspondence should be addressed to F.H. (fhilde@umich.edu). 12 These authors contributed equally to this work 13 These authors contributed equally to this work GenBank accession numbers. INVS cDNA, NM_014425; Invs cDNA, NM_010569; invs cDNA, AF465261; INVS in chromosome 9 genome contig, NT_008470.URLs. Additional information is available at http://danio.mgh.harvard.edu/blast/blast.html. Note: Supplementary information is available on the Nature Genetics website. Competing Interests Statement:The authors declare that they have no competing financial interests. NIH Public AccessAuthor Manuscript Nat Genet. Author manuscript; available in PMC 2013 August 02. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript molecular interaction of inversin with nephrocystin, the product of the gene mutated in NPHP1 and interaction of nephrocystin with β-tubulin, a main component of primary cilia. We show that nephrocystin, inversin and β-tubulin colocalize to primary cilia of renal tubular cells. Furthermore, we produce a PKD-like renal cystic phenotype and randomization of heart looping by knockdown of invs expression in zebrafish. The interaction and colocalization in cilia of inversin, nephrocystin and β-tubulin connect pathogenetic aspects of NPHP to PKD, to primary cilia function and to leftright axis determination.NPHP, an autosomal recessive cystic kidney disease, is the most frequent genetic cause for end-stage renal failure in children and young adults [1][2][3] . Causative mutations in two genes (NPHP1 and NPHP4) have been identified by positional cloning [4][5][6][7] . There is considerable interest in identifying genes associated with NPHP because its most prominent feature is development of renal interstitial fibrosis 8 , which in chronic renal disease of all origin represents the pathogenic event correlated most strongly to loss of renal function 9 . As little was known about the pathogenesis of NPHP, positional cloning was used to identify a new gene, NPHP1, mutations in which cause NPHP1 (OMIM 256100; refs. 4,5). It encodes a novel docking protein, nephrocystin [10][11][12][13] , that interacts with components of cell-cell and cell-matrix signaling, such as focal adhesion kinase 2, tensin, p130Cas and filamin, and with nephrocystin-4 or nephroretinin, the product of NPHP4, mutations in which cause NPHP4 (OMIM 606966; refs. 6,7). Identification of the genes NPHP1 and NPHP4, which are conserved in evolution including in the nematode Caenorhabditis elegans, offered new insights into mechanisms of cell-cell and cell-matrix signaling...

We have previously described individuals presenting with transient neonatal diabetes and showing a variable pattern of DNA hypomethylation at imprinted loci throughout the genome. We now report mutations in ZFP57, which encodes a zinc-finger transcription factor expressed in early development, in seven pedigrees with a shared pattern of mosaic hypomethylation and a conserved range of clinical features. This is the first description of a heritable global imprinting disorder that is compatible with life.

Congenital Heart Defects (CHD) have a neonatal incidence of 0.8-1%1,2. Despite abundant examples of monogenic CHD in humans and mice, CHD has a low absolute sibling recurrence risk (~2.7%)3, suggesting a considerable role for de novo mutations (DNM), and/or incomplete penetrance4,5. De novo protein-truncating variants (PTVs) have been shown to be enriched among the 10% of ‘syndromic’ patients with extra-cardiac manifestations6,7. We exome sequenced 1,891 probands, including both syndromic (S-CHD, n=610) and non-syndromic cases (NS-CHD, n=1,281). In S-CHD, we confirmed a significant enrichment of de novo PTVs, but not inherited PTVs, in known CHD-associated genes, consistent with recent findings8. Conversely, in NS-CHD we observed significant enrichment of PTVs inherited from unaffected parents in CHD-associated genes. We identified three novel genome-wide significant S-CHD disorders caused by DNMs in CHD4, CDK13 and PRKD1. Our study reveals distinct genetic architectures underlying the low sibling recurrence risk in S-CHD and NS-CHD.

Membrane cofactor protein (MCP; CD46) is a widely expressed transmembrane complement regulator. Like factor H it inhibits complement activation by regulating C3b deposition on targets. Factor H mutations occur in 10 -20% of patients with hemolytic uremic syndrome (HUS). We hypothesized that MCP mutations could predispose to HUS, and we sequenced MCP coding exons in affected individuals from 30 families. MCP mutations were detected in affected individuals of three families: a deletion of two amino acids (D237͞S238) in family 1 (heterozygous) and a substitution, S206P, in families 2 (heterozygous) and 3 (homozygous). We evaluated protein expression and function in peripheral blood mononuclear cells from these individuals. An individual with the D237͞S238 deletion had reduced MCP levels and Ϸ50% C3b binding compared with normal controls. Individuals with the S206P change expressed normal quantities of protein, but demonstrated Ϸ50% reduction in C3b binding in heterozygotes and complete lack of C3b binding in homozygotes. MCP expression and function was evaluated in transfectants reproducing these mutations. The deletion mutant was retained intracellularly. S206P protein was expressed on the cell surface but had a reduced ability to prevent complement activation, consistent with its reduced C3b binding and cofactor activity. This study presents further evidence that complement dysregulation predisposes to development of thrombotic microangiopathy and that screening patients for such defects could provide informed treatment strategies.

Atypical hemolytic uremic syndrome (aHUS) is associated with defective complement regulation. Disease-associated mutations have been described in the genes encoding the complement regulators complement factor H, membrane cofactor protein, factor B, and factor I. In this study, we show in two independent cohorts of aHUS patients that deletion of two closely related genes, complement factor H–related 1 (CFHR1) and complement factor H–related 3 (CFHR3), increases the risk of aHUS. Amplification analysis and sequencing of genomic DNA of three affected individuals revealed a chromosomal deletion of ∼84 kb in the RCA gene cluster, resulting in loss of the genes coding for CFHR1 and CFHR3, but leaving the genomic structure of factor H intact. The CFHR1 and CFHR3 genes are flanked by long homologous repeats with long interspersed nuclear elements (retrotransposons) and we suggest that nonallelic homologous recombination between these repeats results in the loss of the two genes. Impaired protection of erythrocytes from complement activation is observed in the serum of aHUS patients deficient in CFHR1 and CFHR3, thus suggesting a regulatory role for CFHR1 and CFHR3 in complement activation. The identification of CFHR1/CFHR3 deficiency in aHUS patients may lead to the design of new diagnostic approaches, such as enhanced testing for these genes.

Hemolytic uremic syndrome (HUS) in adults carries a high morbidity and mortality, and its cause remains unknown despite many theories. Although familial HUS is rare, it affords a unique opportunity to elucidate underlying mechanisms that may have relevance to acquired HUS. We have undertaken a genetic linkage study based on a candidate gene approach. A common area bounded by the markers D1S212 and D1S306, a distance of 26 cM located at 1q32 segregated with the disease (Z max 3.94). We demonstrate that the gene for factor H lies within the region. Subsequent mutation analysis of the factor H gene has revealed two mutations in patients with HUS. In an individual with the sporadic/relapsing form of the disease we have found a mutation comprising a deletion, subsequent frame shift and premature stop codon leading to half normal levels of serum factor H. In one of the three families there is a point mutation in exon 20 causing an arginine to glycine change, which is likely to alter structure and hence function of the factor H protein. Factor H is a major plasma protein that plays a critical regulatory role in the alternative pathway of complement activation. In light of these findings and previous reports of HUS in patients with factor H deficiency, we postulate that abnormalities of factor H may be involved in the etiology of HUS.