DNAAF1 links heart laterality with the AAA+ ATPase RUVBL1 and ciliary intraflagellar transport.

DNAAF1 (LRRC50) is a cytoplasmic protein required for dynein heavy chain assembly and cilia motility, and DNAAF1 mutations cause primary ciliary dyskinesia (PCD; MIM 613193). We describe four families with DNAAF1 mutations and complex congenital heart disease (CHD). In three families, all affected individuals have typical PCD phenotypes. However, an additional family demonstrates isolated CHD (heterotaxy) in two affected siblings, but no clinical evidence of PCD. We identified a homozygous DNAAF1 missense mutation, p.Leu191Phe, as causative for heterotaxy in this family. Genetic complementation in dnaaf1-null zebrafish embryos demonstrated the rescue of normal heart looping with wild-type human DNAAF1, but not the p.Leu191Phe variant, supporting the conserved pathogenicity of this DNAAF1 missense mutation. This observation points to a phenotypic continuum between CHD and PCD, providing new insights into the pathogenesis of isolated CHD. In further investigations of the function of DNAAF1 in dynein arm assembly, we identified interactions with members of a putative dynein arm assembly complex. These include the ciliary intraflagellar transport protein IFT88 and the AAA+ (ATPases Associated with various cellular Activities) family proteins RUVBL1 (Pontin) and RUVBL2 (Reptin). Co-localization studies support these findings, with the loss of RUVBL1 perturbing the co-localization of DNAAF1 with IFT88. We show that RUVBL1 orthologues have an asymmetric left-sided distribution at both the mouse embryonic node and the Kupffer's vesicle in zebrafish embryos, with the latter asymmetry dependent on DNAAF1. These results suggest that DNAAF1-RUVBL1 biochemical and genetic interactions have a novel functional role in symmetry breaking and cardiac development.

Mutations in EXTL3 Cause Neuro-immuno-skeletal Dysplasia Syndrome.

EXTL3 regulates the biosynthesis of heparan sulfate (HS), important for both skeletal development and hematopoiesis, through the formation of HS proteoglycans (HSPGs). By whole-exome sequencing, we identified homozygous missense mutations c.1382C>T, c.1537C>T, c.1970A>G, and c.2008T>G in EXTL3 in nine affected individuals from five unrelated families. Notably, we found the identical homozygous missense mutation c.1382C>T (p.Pro461Leu) in four affected individuals from two unrelated families. Affected individuals presented with variable skeletal abnormalities and neurodevelopmental defects. Severe combined immunodeficiency (SCID) with a complete absence of T cells was observed in three families. EXTL3 was most abundant in hematopoietic stem cells and early progenitor T cells, which is in line with a SCID phenotype at the level of early T cell development in the thymus. To provide further support for the hypothesis that mutations in EXTL3 cause a neuro-immuno-skeletal dysplasia syndrome, and to gain insight into the pathogenesis of the disorder, we analyzed the localization of EXTL3 in fibroblasts derived from affected individuals and determined glycosaminoglycan concentrations in these cells as well as in urine and blood. We observed abnormal glycosaminoglycan concentrations and increased concentrations of the non-sulfated chondroitin disaccharide D0a0 and the disaccharide D0a4 in serum and urine of all analyzed affected individuals. In summary, we show that biallelic mutations in EXTL3 disturb glycosaminoglycan synthesis and thus lead to a recognizable syndrome characterized by variable expression of skeletal, neurological, and immunological abnormalities.

COLEC10 is mutated in 3MC patients and regulates early craniofacial development.

3MC syndrome is an autosomal recessive heterogeneous disorder with features linked to developmental abnormalities. The main features include facial dysmorphism, craniosynostosis and cleft lip/palate; skeletal structures derived from cranial neural crest cells (cNCC). We previously reported that lectin complement pathway genes COLEC11 and MASP1/3 are mutated in 3MC syndrome patients. Here we define a new gene, COLEC10, also mutated in 3MC families and present novel mutations in COLEC11 and MASP1/3 genes in a further five families. The protein products of COLEC11 and COLEC10, CL-K1 and CL-L1 respectively, form heteromeric complexes. We show COLEC10 is expressed in the base membrane of the palate during murine embryo development. We demonstrate how mutations in COLEC10 (c.25C>T; p.Arg9Ter, c.226delA; p.Gly77Glufs*66 and c.528C>G p.Cys176Trp) impair the expression and/or secretion of CL-L1 highlighting their pathogenicity. Together, these findings provide further evidence linking the lectin complement pathway and complement factors COLEC11 and COLEC10 to morphogenesis of craniofacial structures and 3MC etiology.

Rapid Paediatric Sequencing (RaPS): comprehensive real-life workflow for rapid diagnosis of critically ill children.

BACKGROUND: Rare genetic conditions are frequent risk factors for, or direct causes of, paediatric intensive care unit (PICU) admission. Such conditions are frequently suspected but unidentified at PICU admission. Compassionate and effective care is greatly assisted by definitive diagnostic information. There is therefore a need to provide a rapid genetic diagnosis to inform clinical management.To date, whole genome sequencing (WGS) approaches have proved successful in diagnosing a proportion of children with rare diseases, but results may take months to report. Our aim was to develop an end-to-end workflow for the use of rapid WGS for diagnosis in critically ill children in a UK National Health Service (NHS) diagnostic setting. METHODS: We sought to establish a multidisciplinary Rapid Paediatric Sequencing team for case selection, trio WGS, rapid bioinformatics sequence analysis and a phased analysis and reporting system to prioritise genes with a high likelihood of being causal. RESULTS: Trio WGS in 24 critically ill children led to a molecular diagnosis in 10 (42%) through the identification of causative genetic variants. In 3 of these 10 individuals (30%), the diagnostic result had an immediate impact on the individual's clinical management. For the last 14 trios, the shortest time taken to reach a provisional diagnosis was 4 days (median 8.5 days). CONCLUSION: Rapid WGS can be used to diagnose and inform management of critically ill children within the constraints of an NHS clinical diagnostic setting. We provide a robust workflow that will inform and facilitate the rollout of rapid genome sequencing in the NHS and other healthcare systems globally.

Mutations in linker for activation of T cells (LAT) lead to a novel form of severe combined immunodeficiency.

BACKGROUND: Signaling through the T-cell receptor (TCR) is critical for T-cell development and function. Linker for activation of T cells (LAT) is a transmembrane adaptor signaling molecule that is part of the TCR complex and essential for T-cell development, as demonstrated by LAT-deficient mice, which show a complete lack of peripheral T cells. OBJECTIVE: We describe a pedigree affected by a severe combined immunodeficiency phenotype with absent T cells and normal B-cell and natural killer cell numbers. A novel homozygous frameshift mutation in the gene encoding for LAT was identified in this kindred. METHODS: Genetic, molecular, and functional analyses were used to identify and characterize the LAT defect. Clinical and immunologic analysis of patients was also performed and reported. RESULTS: Homozygosity mapping was used to identify potential defective genes. Sanger sequencing of the LAT gene showed a mutation that resulted in a premature stop codon and protein truncation leading to complete loss of function and loss of expression of LAT in the affected family members. We also demonstrate loss of LAT expression and lack of TCR signaling restoration in LAT-deficient cell lines reconstituted with a synthetic LAT gene bearing this severe combined immunodeficiency mutation. CONCLUSION: For the first time, the results of this study show that inherited LAT deficiency should be considered in patients with combined immunodeficiency with T-cell abnormalities.

Mutations in SNX14 cause a distinctive autosomal-recessive cerebellar ataxia and intellectual disability syndrome.

Intellectual disability and cerebellar atrophy occur together in a large number of genetic conditions and are frequently associated with microcephaly and/or epilepsy. Here we report the identification of causal mutations in Sorting Nexin 14 (SNX14) found in seven affected individuals from three unrelated consanguineous families who presented with recessively inherited moderate-severe intellectual disability, cerebellar ataxia, early-onset cerebellar atrophy, sensorineural hearing loss, and the distinctive association of progressively coarsening facial features, relative macrocephaly, and the absence of seizures. We used homozygosity mapping and whole-exome sequencing to identify a homozygous nonsense mutation and an in-frame multiexon deletion in two families. A homozygous splice site mutation was identified by Sanger sequencing of SNX14 in a third family, selected purely by phenotypic similarity. This discovery confirms that these characteristic features represent a distinct and recognizable syndrome. SNX14 encodes a cellular protein containing Phox (PX) and regulator of G protein signaling (RGS) domains. Weighted gene coexpression network analysis predicts that SNX14 is highly coexpressed with genes involved in cellular protein metabolism and vesicle-mediated transport. All three mutations either directly affected the PX domain or diminished SNX14 levels, implicating a loss of normal cellular function. This manifested as increased cytoplasmic vacuolation as observed in cultured fibroblasts. Our findings indicate an essential role for SNX14 in neural development and function, particularly in development and maturation of the cerebellum.

Novel G6B gene variant causes familial autosomal recessive thrombocytopenia and anemia.

OBJECTIVE: To characterize the underlying genetic and molecular defects in a consanguineous family with lifelong blood disorder manifested with thrombocytopenia (low platelets count) and anemia. METHODS: Genetic linkage analysis, exome sequencing, and functional genomics were carried out to identify and characterize the defective gene. RESULTS: We identified a novel truncation mutation (p.C108*) in chromosome 6 open reading frame 25 (C6orf25) gene in this family. We also showed the p.C108* mutation was responsible for destabilizing the encoded truncated G6B protein. Unlike the truncated form, wild-type G6B expression resulted in enhanced K562 differentiation into megakaryocytes and erythrocytes. C6orf25, also known as G6B, is an effector protein for the key hematopoiesis regulators, Src homology region 2 domain-containing phosphatases SHP-1 and SHP-2. CONCLUSION: G6B seems to act through an autosomal recessive mode of disease transmission in this family and regarded as the gene responsible for the observed hematological disorder. This inference is well supported further by in vivo evidence where similar outcomes were reported from G6b-/- and SHP1/2 DKO mouse models.

Mutation of SALL2 causes recessive ocular coloboma in humans and mice.

Ocular coloboma is a congenital defect resulting from failure of normal closure of the optic fissure during embryonic eye development. This birth defect causes childhood blindness worldwide, yet the genetic etiology is poorly understood. Here, we identified a novel homozygous mutation in the SALL2 gene in members of a consanguineous family affected with non-syndromic ocular coloboma variably affecting the iris and retina. This mutation, c.85G>T, introduces a premature termination codon (p.Glu29*) predicted to truncate the SALL2 protein so that it lacks three clusters of zinc-finger motifs that are essential for DNA-binding activity. This discovery identifies SALL2 as the third member of the Drosophila homeotic Spalt-like family of developmental transcription factor genes implicated in human disease. SALL2 is expressed in the developing human retina at the time of, and subsequent to, optic fissure closure. Analysis of Sall2-deficient mouse embryos revealed delayed apposition of the optic fissure margins and the persistence of an anterior retinal coloboma phenotype after birth. Sall2-deficient embryos displayed correct posterior closure toward the optic nerve head, and upon contact of the fissure margins, dissolution of the basal lamina occurred and PAX2, known to be critical for this process, was expressed normally. Anterior closure was disrupted with the fissure margins failing to meet, or in some cases misaligning leading to a retinal lesion. These observations demonstrate, for the first time, a role for SALL2 in eye morphogenesis and that loss of function of the gene causes ocular coloboma in humans and mice.

The kinetochore protein, CENPF, is mutated in human ciliopathy and microcephaly phenotypes.

BACKGROUND: Mutations in microtubule-regulating genes are associated with disorders of neuronal migration and microcephaly. Regulation of centriole length has been shown to underlie the pathogenesis of certain ciliopathy phenotypes. Using a next-generation sequencing approach, we identified mutations in a novel centriolar disease gene in a kindred with an embryonic lethal ciliopathy phenotype and in a patient with primary microcephaly. METHODS AND RESULTS: Whole exome sequencing data from a non-consanguineous Caucasian kindred exhibiting mid-gestation lethality and ciliopathic malformations revealed two novel non-synonymous variants in CENPF, a microtubule-regulating gene. All four affected fetuses showed segregation for two mutated alleles [IVS5-2A>C, predicted to abolish the consensus splice-acceptor site from exon 6; c.1744G>T, p.E582X]. In a second unrelated patient exhibiting microcephaly, we identified two CENPF mutations [c.1744G>T, p.E582X; c.8692 C>T, p.R2898X] by whole exome sequencing. We found that CENP-F colocalised with Ninein at the subdistal appendages of the mother centriole in mouse inner medullary collecting duct cells. Intraflagellar transport protein-88 (IFT-88) colocalised with CENP-F along the ciliary axonemes of renal epithelial cells in age-matched control human fetuses but did not in truncated cilia of mutant CENPF kidneys. Pairwise co-immunoprecipitation assays of mitotic and serum-starved HEKT293 cells confirmed that IFT88 precipitates with endogenous CENP-F. CONCLUSIONS: Our data identify CENPF as a new centriolar disease gene implicated in severe human ciliopathy and microcephaly related phenotypes. CENP-F has a novel putative function in ciliogenesis and cortical neurogenesis.

IFT80, which encodes a conserved intraflagellar transport protein, is mutated in Jeune asphyxiating thoracic dystrophy.

Jeune asphyxiating thoracic dystrophy, an autosomal recessive chondrodysplasia, often leads to death in infancy because of a severely constricted thoracic cage and respiratory insufficiency; retinal degeneration, cystic renal disease and polydactyly may be complicating features. We show that IFT80 mutations underlie a subset of Jeune asphyxiating thoracic dystrophy cases, establishing the first association of a defective intraflagellar transport (IFT) protein with human disease. Knockdown of ift80 in zebrafish resulted in cystic kidneys, and knockdown in Tetrahymena thermophila produced shortened or absent cilia.

Variable phenotype of severe immunodeficiencies associated with RMRP gene mutations.

PURPOSE: Mutations in RMRP primarily give rise to Cartilage Hair Hypoplasia (CHH), a highly diverse skeletal disorder which can be associated with severe immunodeficiency. Increased availability of RMRP mutation screening has uncovered a number of infants with significant immunodeficiency but only mild or absent skeletal features. We surveyed the clinical and immunological phenotype of children who have undergone allogeneic haematopoietic stem cell transplantation for this condition in the UK. METHODS: Thirteen patients with confirmed RMRP mutations underwent allogeneic stem cell transplantation (SCT) at two nationally commissioned centres using a variety of donors and conditioning regimens. Records were retrospectively reviewed. RESULTS: Median time from clinical presentation to diagnosis was 12 months (range 1 to 276 months), with three infants diagnosed with severe combined immunodeficiency (SCID) without radiographical manifestations of CHH. A total of 17 allogeneic procedures were performed on 13 patients including two stem-cell top-ups. The median age at transplant was 32.4 months (range 1.5 to 125 months). Of the eleven surviving patients, median follow-up was 50 months (range 21.6 to 168 months). CONCLUSIONS: RMRP mutations can cause short stature and significant immunodeficiency which can be corrected by allogeneic SCT and the diagnosis should be considered even in the absence of skeletal manifestations.

Targeted gene panel sequencing in children with very early onset inflammatory bowel disease--evaluation and prospective analysis.

BACKGROUND: Multiple monogenetic conditions with partially overlapping phenotypes can present with inflammatory bowel disease (IBD)-like intestinal inflammation. With novel genotype-specific therapies emerging, establishing a molecular diagnosis is becoming increasingly important. DESIGN: We have introduced targeted next-generation sequencing (NGS) technology as a prospective screening tool in children with very early onset IBD (VEOIBD). We evaluated the coverage of 40 VEOIBD genes in two separate cohorts undergoing targeted gene panel sequencing (TGPS) (n=25) and whole exome sequencing (WES) (n=20). RESULTS: TGPS revealed causative mutations in four genes (IL10RA, EPCAM, TTC37 and SKIV2L) discovered unexpected phenotypes and directly influenced clinical decision making by supporting as well as avoiding haematopoietic stem cell transplantation. TGPS resulted in significantly higher median coverage when compared with WES, fewer coverage deficiencies and improved variant detection across established VEOIBD genes. CONCLUSIONS: Excluding or confirming known VEOIBD genotypes should be considered early in the disease course in all cases of therapy-refractory VEOIBD, as it can have a direct impact on patient management. To combine both described NGS technologies would compensate for the limitations of WES for disease-specific application while offering the opportunity for novel gene discovery in the research setting.

Combined exome and whole-genome sequencing identifies mutations in ARMC4 as a cause of primary ciliary dyskinesia with defects in the outer dynein arm.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a rare, genetically heterogeneous ciliopathy disorder affecting cilia and sperm motility. A range of ultrastructural defects of the axoneme underlie the disease, which is characterised by chronic respiratory symptoms and obstructive lung disease, infertility and body axis laterality defects. We applied a next-generation sequencing approach to identify the gene responsible for this phenotype in two consanguineous families. METHODS AND RESULTS: Data from whole-exome sequencing in a consanguineous Turkish family, and whole-genome sequencing in the obligate carrier parents of a consanguineous Pakistani family was combined to identify homozygous loss-of-function mutations in ARMC4, segregating in all five affected individuals from both families. Both families carried nonsense mutations within the highly conserved armadillo repeat region of ARMC4: c.2675C>A; pSer892* and c.1972G>T; p.Glu658*. A deficiency of ARMC4 protein was seen in patient's respiratory cilia accompanied by loss of the distal outer dynein arm motors responsible for generating ciliary beating, giving rise to cilia immotility. ARMC4 gene expression is upregulated during ciliogenesis, and we found a predicted interaction with the outer dynein arm protein DNAI2, mutations in which also cause PCD. CONCLUSIONS: We report the first use of whole-genome sequencing to identify gene mutations causing PCD. Loss-of-function mutations in ARMC4 cause PCD with situs inversus and cilia immotility, associated with a loss of the distal outer (but not inner) dynein arms. This addition of ARMC4 to the list of genes associated with ciliary outer dynein arm defects expands our understanding of the complexities of PCD genetics.

ARNT2 mutation causes hypopituitarism, post-natal microcephaly, visual and renal anomalies.

We describe a previously unreported syndrome characterized by secondary (post-natal) microcephaly with fronto-temporal lobe hypoplasia, multiple pituitary hormone deficiency, seizures, severe visual impairment and abnormalities of the kidneys and urinary tract in a highly consanguineous family with six affected children. Homozygosity mapping and exome sequencing revealed a novel homozygous frameshift mutation in the basic helix-loop-helix transcription factor gene ARNT2 (c.1373_1374dupTC) in affected individuals. This mutation results in absence of detectable levels of ARNT2 transcript and protein from patient fibroblasts compared with controls, consistent with nonsense-mediated decay of the mutant transcript and loss of ARNT2 function. We also show expression of ARNT2 within the central nervous system, including the hypothalamus, as well as the renal tract during human embryonic development. The progressive neurological abnormalities, congenital hypopituitarism and post-retinal visual pathway dysfunction in affected individuals demonstrates for the first time the essential role of ARNT2 in the development of the hypothalamo-pituitary axis, post-natal brain growth, and visual and renal function in humans.

DICER1 syndrome: clarifying the diagnosis, clinical features and management implications of a pleiotropic tumour predisposition syndrome.

BACKGROUND: Constitutional DICER1 mutations were recently reported to cause familial pleuropulmonary blastoma (PPB). AIM: To investigate the contribution and phenotypic spectrum of constitutional and somatic DICER1 mutations to cancer. METHODS AND RESULTS: The authors sequenced DICER1 in constitutional DNA from 823 unrelated patients with a variety of tumours and in 781 cancer cell lines. Constitutional DICER1 mutations were identified in 19 families including 11/14 with PPB, 2/3 with cystic nephroma, 4/7 with ovarian Sertoli-Leydig-type tumours, 1/243 with Wilms tumour (this patient also had a Sertoli-Leydig tumour), 1/1 with intraocular medulloepithelioma (this patient also had PPB), 1/86 with medulloblastoma/infratentorial primitive neuroectodermal tumour, and 1/172 with germ cell tumour. The inheritance was investigated in 17 families. DICER1 mutations were identified in 25 relatives: 17 were unaffected, one mother had ovarian Sertoli-Leydig tumour, one half-sibling had cystic nephroma, and six relatives had non-toxic thyroid cysts/goitre. Analysis of eight tumours from DICER1 mutation-positive patients showed universal retention of the wild-type allele. DICER1 truncating mutations were identified in 4/781 cancer cell lines; all were in microsatellite unstable lines and therefore unlikely to be driver mutations. CONCLUSION: Constitutional DICER1 haploinsufficiency predisposes to a broad range of tumours, making a substantial contribution to PPB, cystic nephroma and ovarian Sertoli-Leydig tumours, but a smaller contribution to other tumours. Most mutation carriers are unaffected, indicating that tumour risk is modest. The authors define the clinical contexts in which DICER1 mutation testing should be considered, the associated tumour risks, and the implications for at-risk individuals. They have termed this condition 'DICER1 syndrome'. ACCESSION NUMBERS: The cDNA Genbank accession number for the DICER1 sequence reported in this paper is NM_030621.2.

The C76R transmembrane activator and calcium modulator cyclophilin ligand interactor mutation disrupts antibody production and B-cell homeostasis in heterozygous and homozygous mice.

BACKGROUND: Mutations in TNFRSF13B, the gene encoding transmembrane activator and calcium modulator cyclophilin ligand interactor (TACI), are found in 10% of patients with common variable immunodeficiency. However, the most commonly detected mutation is the heterozygous change C104R, which is also found in 0.5% to 1% of healthy subjects. The contribution of the C104R mutation to the B-cell defects observed in patients with common variable immunodeficiency therefore remains unclear. OBJECTIVE: We sought to define the functional consequences of the C104R mutation on B-cell function. METHODS: We performed in vitro studies of TACI C104R expression and signaling. A knock-in mouse with the equivalent mutation murine TACI (mTACI) C76R was generated as a physiologically relevant model of human disease. We examined homozygous and heterozygous C76R mutant mice alongside wild-type littermates and studied specific B-cell lineages and antibody responses to T cell-independent and T cell-dependent challenge. RESULTS: C104R expression and ligand binding are significantly diminished when the mutant protein is expressed in 293T cells or in patients' cell lines. This leads to defective nuclear factor κB activation, which is proportionally restored by reintroduction of wild-type TACI. Mice heterozygous and homozygous for mTACI C76R exhibit significant B-cell dysfunction with splenomegaly, marginal zone B-cell expansion, diminished immunoglobulin production and serological responses to T cell-independent antigen, and abnormal immunoglobulin synthesis. CONCLUSIONS: These data show that the C104R mutation and its murine equivalent, C76R, can significantly disrupt TACI function, probably through haploinsufficiency. Furthermore, the heterozygous C76R mutation alone is sufficient to disturb B-cell function with lymphoproliferation and immunoglobulin production defects.

ZSWIM7 Is Associated With Human Female Meiosis and Familial Primary Ovarian Insufficiency.

BACKGROUND: Primary ovarian insufficiency (POI) affects 1% of women and is associated with significant medical consequences. A genetic cause for POI can be found in up to 30% of women, elucidating key roles for these genes in human ovary development. OBJECTIVE: We aimed to identify the genetic mechanism underlying early-onset POI in 2 sisters from a consanguineous pedigree. METHODS: Genome sequencing and variant filtering using an autosomal recessive model was performed in the 2 affected sisters and their unaffected family members. Quantitative reverse transcriptase PCR (qRT-PCR) and RNA sequencing were used to study the expression of key genes at critical stages of human fetal gonad development (Carnegie Stage 22/23, 9 weeks post conception (wpc), 11 wpc, 15/16 wpc, 19/20 wpc) and in adult tissue. RESULTS: Only 1 homozygous variant cosegregating with the POI phenotype was found: a single nucleotide substitution in zinc finger SWIM-type containing 7 (ZSWIM7), NM_001042697.2: c.173C > G; resulting in predicted loss-of-function p.(Ser58*). qRT-PCR demonstrated higher expression of ZSWIM7 in the 15/16 wpc ovary compared with testis, corresponding to peak meiosis in the fetal ovary. RNA sequencing of fetal gonad samples showed that ZSWIM7 has a similar temporal expression profile in the developing ovary to other homologous recombination genes. MAIN CONCLUSIONS: Disruption of ZSWIM7 is associated with POI in humans. ZSWIM7 is likely to be important for human homologous recombination; these findings expand the range of genes associated with POI in women.

Relevance of biallelic versus monoallelic TNFRSF13B mutations in distinguishing disease-causing from risk-increasing TNFRSF13B variants in antibody deficiency syndromes.

TNFRSF13B encodes transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI), a B cell- specific tumor necrosis factor (TNF) receptor superfamily member. Both biallelic and monoallelic TNFRSF13B mutations were identified in patients with common variable immunodeficiency disorders. The genetic complexity and variable clinical presentation of TACI deficiency prompted us to evaluate the genetic, immunologic, and clinical condition in 50 individuals with TNFRSF13B alterations, following screening of 564 unrelated patients with hypogammaglobulinemia. We identified 13 new sequence variants. The most frequent TNFRSF13B variants (C104R and A181E; n=39; 6.9%) were also present in a heterozygous state in 2% of 675 controls. All patients with biallelic mutations had hypogammaglobulinemia and nearly all showed impaired binding to a proliferation-inducing ligand (APRIL). However, the majority (n=41; 82%) of the pa-tients carried monoallelic changes in TNFRSF13B. Presence of a heterozygous mutation was associated with antibody deficiency (P< .001, relative risk 3.6). Heterozygosity for the most common mutation, C104R, was associated with disease (P< .001, relative risk 4.2). Furthermore, heterozygosity for C104R was associated with low numbers of IgD(-)CD27(+) B cells (P= .019), benign lymphoproliferation (P< .001), and autoimmune complications (P= .001). These associations indicate that C104R heterozygosity increases the risk for common variable immunodeficiency disorders and influences clinical presentation.

Novel missense variants in the RNF213 gene from a European family with Moyamoya disease.

In this report, we present a European family with six individuals affected with Moyamoya disease (MMD). We detected two novel missense variants in the Moyamoya susceptibility gene RNF213, c.12553A>G (p.(Lys4185Glu)) and c.12562G>A (p.(Ala4188Thr)). Cosegregation of the variants with MMD, as well as a previous report of a variant affecting the same amino acid residue in unrelated MMD patients, supports the role of RNF213 in the pathogenesis of MMD.