Dieter Furthner

Gains of glycosylation comprise an unexpectedly large group of pathogenic mutations

Mutations involving gains of glycosylation have been considered rare, and the pathogenic role of the new carbohydrate chains has never been formally established. We identified three children with mendelian susceptibility to mycobacterial disease who were homozygous with respect to a missense mutation in IFNGR2 creating a new N-glycosylation site in the IFNγR2 chain. The resulting additional carbohydrate moiety was both necessary and sufficient to abolish the cellular response to IFNγ. We then searched the Human Gene Mutation Database for potential gain-of-N-glycosylation missense mutations; of 10,047 mutations in 577 genes encoding proteins trafficked through the secretory pathway, we identified 142 candidate mutations (∼1.4%) in 77 genes (∼13.3%). Six mutant proteins bore new N-linked carbohydrate moieties. Thus, an unexpectedly high proportion of mutations that cause human genetic disease might lead to the creation of new N-glycosylation sites. Their pathogenic effects may be a direct consequence of the addition of N-linked carbohydrate.

Haploinsufficiency at the human IFNGR2 locus contributes to mycobacterial disease

Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare syndrome, the known genetic etiologies of which impair the production of, or the response to interferon-gamma (IFN-γ). We report here a patient (P1) with MSMD whose cells display mildly impaired responses to IFN-γ, at levels, however, similar to those from MSMD patients with autosomal recessive (AR) partial IFN-γR2 or STAT1 deficiency. Whole-exome sequencing (WES) and Sanger sequencing revealed only one candidate variation for both MSMD-causing and IFN-γ-related genes. P1 carried a heterozygous frame-shift IFNGR2 mutation inherited from her father. We show that the mutant allele is intrinsically loss-of-function and not dominant-negative, suggesting haploinsufficiency at the IFNGR2 locus. We also show that Epstein-Barr virus transformed B lymphocyte cells from 10 heterozygous relatives of patients with AR complete IFN-γR2 deficiency respond poorly to IFN-γ, in some cases as poorly as the cells of P1. Naive CD4(+) T cells and memory IL-4-producing T cells from these individuals also responded poorly to IFN-γ, whereas monocytes and monocyte-derived macrophages (MDMs) did not. This is consistent with the lower levels of expression of IFN-γR2 in lymphoid than in myeloid cells. Overall, MSMD in this patient is probably due to autosomal dominant (AD) IFN-γR2 deficiency, resulting from haploinsufficiency, at least in lymphoid cells. The clinical penetrance of AD IFN-γR2 deficiency is incomplete, possibly due, at least partly, to the variability of cellular responses to IFN-γ in these individuals.

Fatal Epstein–Barr virus encephalitis in a 12-year-old child: an underappreciated neurological complication?

Background A 12-year-old boy presented to a community hospital with fever, malaise and fatigue. A polymerase chain reaction test of the cerebrospinal fluid was positive for Epstein–Barr virus. Despite intensive care treatment and antiviral drugs, the patient died 1 month after his initial presentation.Investigations Physical examination, polymerase chain reaction analysis of the cerebrospinal fluid, brain MRI, immunohistochemistry and molecular biological investigations of postmortem brain samples.Diagnosis Epstein–Barr Virus encephalitis.Management Aciclovir, intensive care treatment with intubation, sedation, antiepileptic drugs.

Whole exome sequencing in 342 congenital cardiac left sided lesion cases reveals extensive genetic heterogeneity and complex inheritance patterns

BackgroundLeft-sided lesions (LSLs) account for an important fraction of severe congenital cardiovascular malformations (CVMs). The genetic contributions to LSLs are complex, and the mutations that cause these malformations span several diverse biological signaling pathways: TGFB, NOTCH, SHH, and more. Here, we use whole exome sequence data generated in 342 LSL cases to identify likely damaging variants in putative candidate CVM genes.MethodsUsing a series of bioinformatics filters, we focused on genes harboring population-rare, putative loss-of-function (LOF), and predicted damaging variants in 1760 CVM candidate genes constructed a priori from the literature and model organism databases. Gene variants that were not observed in a comparably sequenced control dataset of 5492 samples without severe CVM were then subjected to targeted validation in cases and parents. Whole exome sequencing data from 4593 individuals referred for clinical sequencing were used to bolster evidence for the role of candidate genes in CVMs and LSLs.ResultsOur analyses revealed 28 candidate variants in 27 genes, including 17 genes not previously associated with a human CVM disorder, and revealed diverse patterns of inheritance among LOF carriers, including 9 confirmed de novo variants in both novel and newly described human CVM candidate genes (ACVR1, JARID2, NR2F2, PLRG1, SMURF1) as well as established syndromic CVM genes (KMT2D, NF1, TBX20, ZEB2). We also identified two genes (DNAH5, OFD1) with evidence of recessive and hemizygous inheritance patterns, respectively. Within our clinical cohort, we also observed heterozygous LOF variants in JARID2 and SMAD1 in individuals with cardiac phenotypes, and collectively, carriers of LOF variants in our candidate genes had a four times higher odds of having CVM (odds ratio = 4.0, 95% confidence interval 2.5–6.5).ConclusionsOur analytical strategy highlights the utility of bioinformatic resources, including human disease records and model organism phenotyping, in novel gene discovery for rare human disease. The results underscore the extensive genetic heterogeneity underlying non-syndromic LSLs, and posit potential novel candidate genes and complex modes of inheritance in this important group of birth defects.

Facial Nerve Paralysis in Children: Is It as Benign as Supposed?

BACKGROUND Facial nerve paralysis is a common disease in children. Most of the patients show complete recovery. This single-center cohort study exclusively included pediatric patients to investigate the outcome of all patients with facial nerve palsy. METHODS Hospital records of all the patients admitted to the Childrens Hospital in Linz between January 2005 and December 2010 with facial nerve paralysis were reviewed. Patients with peripheral facial nerve palsy were invited for clinical reevaluation between July 2011 and October 2011. The House-Brackmann score was used for reassessment. RESULTS Fifty-six patients agreed to return for an additional clinical reevaluation. Study participants were divided in two groups according to their House-Brackmann scores: group 1 (n = 44), with a score <2 were considered good outcomes, and group 2 (n = 12), with a score ≥ 2 showed persistent mild to moderate dysfunction of the facial nerve and were considered moderate outcomes. The most important finding was the difference of the reported time to remission (P = 0.003) between the groups. CONCLUSION The results of this study indicate that facial paralysis in children is not as benign as supposed. It is suggested that patients and their guardians be informed that a slight face asymmetry may persist, but functional recovery in general is excellent.

Prospective analysis on brain magnetic resonance imaging in children

BACKGROUND Previous studies have addressed the prevalence of incidental findings in adult populations. There are few studies following paediatric patients, most of data were retrieved retrospectively. We conducted a prospective study to determine the prevalence of incidental, pathologic and normal findings in a symptomatic paediatric population. METHODS The subjects of this prospective single centre study are 436 children aged 0-18 years with clinical symptoms and subsequent first brain MRI. Normal, incidental as well as pathologic MRI findings are documented in association with age, gender, neurological examination and previous investigations (CCT, EEG). Secondary outcome parameters are defined as MRI results and their implications. Two board-certified radiologists prospectively analysed MR images without knowing the result from each other. RESULTS The 436 patients with brain MRI were categorized into three groups as follows: 155 (35.5%) patients had normal findings, 163 (37.4%) had incidental findings and 118 (27.1%) had pathological findings in brain MRI. When adding patients with pathologic and incidental findings we report even more (47.9%). We analysed the correlation between neurologic examination and MRI result and it was significant (p-value 0.0008). The p-value for concordance of both radiology reports was <0.001 and therefore highly significant. CONCLUSION To our knowledge this is the first prospective paediatric study reporting the prevalence of normal, pathologic and incidental findings in brain MRI in symptomatic children. Incidental findings are common in paediatric patients but we report the highest prevalence. Our data may help guiding management decision in a consistent and clinically appropriate manner.

Assessment of large copy number variants in patients with apparently isolated congenital left-sided cardiac lesions reveals clinically relevant genomic events

Congenital left‐sided cardiac lesions (LSLs) are a significant contributor to the mortality and morbidity of congenital heart disease (CHD). Structural copy number variants (CNVs) have been implicated in LSL without extra‐cardiac features; however, non‐penetrance and variable expressivity have created uncertainty over the use of CNV analyses in such patients. High‐density SNP microarray genotyping data were used to infer large, likely‐pathogenic, autosomal CNVs in a cohort of 1,139 probands with LSL and their families. CNVs were molecularly confirmed and the medical records of individual carriers reviewed. The gene content of novel CNVs was then compared with public CNV data from CHD patients. Large CNVs (>1 MB) were observed in 33 probands (∼3%). Six of these were de novo and 14 were not observed in the only available parent sample. Associated cardiac phenotypes spanned a broad spectrum without clear predilection. Candidate CNVs were largely non‐recurrent, associated with heterozygous loss of copy number, and overlapped known CHD genomic regions. Novel CNV regions were enriched for cardiac development genes, including seven that have not been previously associated with human CHD. CNV analysis can be a clinically useful and molecularly informative tool in LSLs without obvious extra‐cardiac defects, and may identify a clinically relevant genomic disorder in a small but important proportion of these individuals.

Aminoterminal pro-B-type natriuretic peptide: heart or lung disease in the neonate?.

Objectives: B-type natriuretic peptides have been shown to enable differentiation between heart and lung diseases in adults and children. In neonates, the role of natriuretic peptides for diagnosis of congenital heart defect (CHD) is not yet ascertained. The purpose of this single-center prospective study was to investigate aminoterminal B-type natriuretic peptide concentrations and their time courses during the first 5 days of life in neonates with CHD compared with neonates with respiratory distress. Design: Single-center prospective study. Setting: Tertiary-care neonatal ICU. Patients: Aminoterminal B-type natriuretic peptide levels of 40 neonates with arterial duct–dependent CHD and of 40 neonates with respiratory distress without CHD were analyzed on the first, second, third, and fifth day of life. Main Results: Mean aminoterminal B-type natriuretic peptide concentrations in the CHD group were significantly higher on the second (14191 vs. 4872 pg/mL), third (17790 vs. 3524 pg/mL), and fifth day (17015 vs. 4044 pg/mL), but not on the first day of life. Repeated measurements analysis of variance revealed a significantly different time course of aminoterminal B-type natriuretic peptide concentrations between the two groups. Conclusions: On the first day of life, aminoterminal B-type natriuretic peptide cannot differentiate between CHD and respiratory distress without CHD in the neonate. From the second day onwards, aminoterminal B-type natriuretic peptide in neonates with CHD shows higher values and a different time course and enables differentiation between CHD and respiratory distress due to other than cardiac reasons.

Education, school type and screen time were associated with overweight and obesity in 2930 adolescents

This cross‐sectional study analysed the influence of socio‐economic factors on screen time, overweight and obesity.