Mutations in the LRBA gene (encoding the lipopolysaccharide-responsive and beige-like anchor protein) cause a syndrome of autoimmunity, lymphoproliferation, and humoral immune deficiency. The biological role of LRBA in immunologic disease is unknown. We found that patients with LRBA deficiency manifested a dramatic and sustained improvement in response to abatacept, a CTLA4 (cytotoxic T lymphocyte antigen-4)-immunoglobulin fusion drug. Clinical responses and homology of LRBA to proteins controlling intracellular trafficking led us to hypothesize that it regulates CTLA4, a potent inhibitory immune receptor. We found that LRBA colocalized with CTLA4 in endosomal vesicles and that LRBA deficiency or knockdown increased CTLA4 turnover, which resulted in reduced levels of CTLA4 protein in FoxP3(+) regulatory and activated conventional T cells. In LRBA-deficient cells, inhibition of lysosome degradation with chloroquine prevented CTLA4 loss. These findings elucidate a mechanism for CTLA4 trafficking and control of immune responses and suggest therapies for diseases involving the CTLA4 pathway.

Familial hemophagocytic lymphohistiocytosis (HLH) is

This cohort of fatal influenza A(H1N1) infections confirms the presence of hemophagocytosis and HLH pathology. Moreover, the high percentage of HLH gene mutations suggests they are risk factors for mortality among individuals with influenza A(H1N1) infection.

Key Points Synergistic effects were observed in the granule mediated lymphocyte cytotoxicity. Digenic pathogenesis contributed to the development of hemophagocytic lymphohistiocytosis.

Objective: Mutations in both alleles of parkin have been shown to result in Parkinson disease (PD).However, it is unclear whether haploinsufficiency (presence of a mutation in only 1 of the 2 parkin alleles) increases the risk for PD. Methods:We performed comprehensive dosage and sequence analysis of all 12 exons of parkin in a sample of 520 independent patients with familial PD and 263 controls. We evaluated whether presence of a single parkin mutation, either a sequence (point mutation or small insertion/deletion) or dosage (whole exon deletion or duplication) mutation, was found at increased frequency in cases as compared with controls. We then compared the clinical characteristics of cases with 0, 1, or 2 parkin mutations. Results:We identified 55 independent patients with PD with at least 1 parkin mutation and 9 controls with a single sequence mutation. Cases and controls had a similar frequency of single sequence mutations (3.1% vs 3.4%, p ϭ 0.83); however, the cases had a significantly higher rate of dosage mutations (2.6% vs 0%, p ϭ 0.009). Cases with a single dosage mutation were more likely to have an earlier age at onset (50% with onset at Յ45 years) compared with those with no parkin mutations (10%, p ϭ 0.00002); this was not true for cases with only a single sequence mutation (25% with onset at Յ45 years, p ϭ 0.06). Conclusions:Parkin haploinsufficiency, specifically for a dosage mutation rather than a point mutation or small insertion/deletion, is a risk factor for familial PD and may be associated with earlier age at onset. Neurology

Invasive fungal infections are a significant cause of morbidity and mortality in recipients of hematopoietic stem cell transplantation (HSCT), warranting antifungal prophylaxis as a standard of care in these patients. Voriconazole is commonly used in this setting because of its broad-spectrum activity and available dosage forms. There is wide well-known inter- and intrapatient variability in voriconazole concentrations, in part because concentrations are affected by common CYP2C19 polymorphisms. In 2 successive studies we have optimized voriconazole dosing to achieve target voriconazole serum concentrations using a genotype-specific dosing algorithm for antifungal prophylaxis in the post-HSCT period. In our pilot study all patients undergoing HSCT who received voriconazole antifungal prophylaxis were prospectively followed. Voriconazole concentrations were monitored weekly and doses adjusted until concentrations reached between 1 and 5.5 μg/L. The most common CYP2C19 polymorphisms were determined and correlated with voriconazole dose and time required to reach the target concentration range. In the subsequent study patients receiving voriconazole prophylaxis were dosed based on their CYP2C19 genotype and followed prospectively. In the pilot study 25 patients received voriconazole as antifungal prophylaxis for a median of 49 days (range, 15 to 196 days). The median time to reach the target concentration was 34 days for extensive metabolizers and 11 days for poor metabolizers. Three patients were genotyped as intermediate metabolizers; they reached the target concentration in a median of 56 days. Similarly, 2 patients who were genotyped as ultrarapid metabolizers reached the target range in 18 and 25 days. The time and dose required to reach the adequate concentration showed a trend toward correlation with individual CYP2C19 genotype, although voriconazole concentrations showed large interpatient variability in wild-type patients (extensive metabolizers). In our follow-up study, 20 patients received voriconazole prophylaxis prospectively dosed based on their CYP2C19 genotype. The median times to reach the target concentration using genotype-guided dosing were 9, 6.5, and 4 days for ultrarapid, extensive, and intermediate metabolizers, respectively. Overall, the median time to reach the target concentration with genotype-guided dosing was 6.5 days compared with a median time of 29 days when all patients were started on the same dose regardless of CYP2C19 genotype (P < .001). Our data show that traditional voriconazole dosing does not lead to timely achievement of target levels for fungal prophylaxis. However, a genotype-directed dosing algorithm allows patients to reach the voriconazole target range significantly sooner, providing better prophylaxis against fungal infections in the immediate post-transplant period.

Objective. To evaluate the performance of a next-generation sequencing (NGS)-based targeted resequencing genetic test, OtoSeq, to identify the sequence variants in the genes causing sensorineural hearing loss (SNHL).Study Design. Retrospective study. Setting. Tertiary children's hospital.Subjects and Methods. A total of 8 individuals presenting with prelingual hearing loss were used in this study. The coding and flanking intronic regions of 24 well-studied SNHL genes were enriched using microdroplet polymerase chain reaction and sequenced on an Illumina HiSeq 2000 sequencer. The filtered high-quality sequence reads were mapped to reference sequence, and variants were detected using NextGENe software.Results. A total of 1148 sequence variants were detected in 8 samples in 24 genes. Using in-house developed NGS data analysis criteria, we classified 810 (~71%) of these variants as potential true variants that include previously detected pathogenic mutations in 5 patients. To validate our strategy, we Sanger sequenced the target regions of 5 of the 24 genes, accounting for about 29.2% of all target sequence. Our results showed .99.99% concordance between NGS and Sanger sequencing in these 5 genes, resulting in an analytical sensitivity and specificity of 100% and 99.997%, respectively. We were able to successfully detect single base substitutions, small deletions, and insertions of up to 22 nucleotides.Conclusion. This study demonstrated that our NGS-based mutation screening strategy is highly sensitive and specific in detecting sequence variants in the SNHL genes. Therefore, we propose that this NGS-based targeted sequencing method would be an alternative to current technologies for identifying the multiple genetic causes of SNHL. 1-3 About two-thirds of prelingual-onset SNHL has a genetic etiology, and the rest is due to environmental and unidentified genetic factors. It is estimated that about 70% of patients have nonsyndromic SNHL, and the remaining 30% of patients have syndromic SNHL, where SNHL is accompanied by other physical manifestations.2,3 In the majority of patients, inherited SNHL is monogenic and classified into 4 groups based on the inheritance pattern: autosomal recessive is the most common type, occurring in about 80% of patients, and autosomal dominant accounts for most of the other 20%, whereas X-linked and mitochondrial account for only 1% to 2% of the patients.4-6 Inherited SNHL is genetically heterogeneous, and to date, more than 150 deafness loci have been identified, including 39 autosomal recessive, 25 autosomal dominant, 3 X-linked, and 2 mitochondrial genes. 7Establishing genetic causes of SNHL is important in the clinical management of patients and their families, and thus the continued search for the unidentified genetic causes is of clinical relevance. Candidate genes for syndromic SNHL are determined based on associated symptoms, whereas this approach is not viable for nonsyndromic SNHL as the phenotype caused by most of the genes is indistinguishable. Therefore, screening th...

Objective: A recent study reported that mutations in a gene on chromosome 2q36-37, GIGYF2, result in Parkinson disease (PD). We have previously reported linkage to this chromosomal region in a sample of multiplex PD families, with the strongest evidence of linkage obtained using the subset of the sample having the strongest family history of disease and meeting the strictest diagnostic criteria. We have tested whether mutations in GIGYF2 may account for the previously observed linkage finding. Methods:We sequenced the GIGYF2 coding region in 96 unrelated patients with PD used in our original study that contributed to the chromosome 2q36-37 linkage signal. Subsequently, we genotyped the entire sample of 566 multiplex PD kindreds as well as 1,447 controls to test whether variants in GIGYF2 are causative or increase susceptibility for PD.