Comprehensive next-generation sequencing analyses of hypoparathyroidism: identification of novel GCM2 mutations.

CONTEXT: In most patients with hypoparathyroidism (HP), the etiology is not defined clinically. Eight genes (AIRE, CASR, CLDN16, GATA3, GCM2, PTH, TBCE, and TRPM6) are known to be responsible genes associated with HP; however, no previous study has screened the eight responsible genes comprehensively in HP patients. OBJECTIVES: This study was conducted to determine the genetic defect in HP patients. We also described clinical and molecular findings of two HP patients with novel GCM2 mutations. SUBJECTS AND METHODS: We enrolled 20 nonconsanguineous Japanese patients with child-onset permanent HP without 22q11 deletion. Mutations and genomic rearrangements involving the eight genes were screened by targeted next-generation sequencing (NGS). We also screened genetic rearrangements by array comparative genomic hybridization (aCGH) in the mutation-negative patients. A putative deletion, which was suspected by NGS, was additionally analyzed by droplet digital PCR (ddPCR) and junction PCR. Identified novel nucleotide-level GCM2 mutants were characterized in vitro. RESULTS: We identified seven patients with a single gene disorder, including a CASR mutation, GATA3 mutations, and novel GCM2 mutations (R367Tfs*15, T370M, and the deletion encompassing exon 1). This submicroscopic deletion, which had been suspected by NGS, could not be detected by aCGH and was confirmed by ddPCR and junction PCR. Functional studies of R367Tfs*- and T370M-GCM2 demonstrated a reduction of target gene transactivation in both. CONCLUSIONS: Using comprehensive NGS analyses, we identified the genetic defect in 35% of HP patients in our cohort and discovered novel GCM2 mutations including submicroscopic deletion that was undetectable by aCGH.

Hydrocephalus with Hirschsprung disease: severe end of X-linked hydrocephalus spectrum.

L1CAM molecule is a cell adhesion molecule in nervous and enteric systems and is responsible for X-linked hydrocephalus (XLH) spectrum, which is a rare condition with severe congenital hydrocephalus, dysgenesis of the corpus callosum, intellectual disability, spasticity, and adducted thumbs. Several cases of XLH accompanied by Hirschsprung disease (HSCR) have been reported in the literature, but whether HSCR results from a gain-of-function mutation in cases with XLH, i.e., a neomorphic mutation, or the severe end of the L1CAM mutation spectrum remains unclear. The present patient was a Japanese boy with severe congenital hydrocephalus with aqueductal stenosis as well as hypoplasia of the corpus callosum. HSCR had been confirmed by a biopsy. A mutation analysis of the L1CAM gene showed a C61T mutation in exon 1, resulting in a truncating nonsense mutation at amino acid position 21 and producing an extremely short protein that was unlikely to interact with other proteins. These findings suggest that XLH-HSCR represents the severe end of the XLH spectrum, rather than a neomorphic mutation. A thorough abdominal investigation to rule out HSCR should be considered in patients with XLH accompanied by severe constipation.

Meningitis and septicemia caused by nontypeable Haemophilus influenzae in a previously healthy 2-year-old girl.

Nontypeable Haemophilus influenzae (NTHi) commonly colonizes the upper respiratory tract of children and causes otitis media, sinusitis, and bronchitis. Invasive NTHi diseases such as meningitis and septicemia have rarely been reported, especially in children with underlying predisposing conditions such as head trauma and immune compromise. However, we report a previously healthy 2-year-old girl who developed meningitis and septicemia caused by NTHi biotype ΙΙΙ. She was treated with dexamethasone, meropenem, and ceftriaxone, and recovered uneventfully. We wish to emphasize that NTHi should be borne in mind as a potential pathogen that can cause meningitis and septicemia, even in previously healthy children.

Eating disorders with binge-eating behaviour are associated with the s allele of the 3'-UTR VNTR polymorphism of the dopamine transporter gene.

OBJECTIVE: The dopaminergic system is associated with feelings of pleasure and reward and with positive hedonic processes related to food, sexual activity and certain substances. Because it is recognized that patients who have eating disorders with binge-eating behaviour have a high comorbidity of substance dependence, we examined the association between the variable number of tandem repeats (VNTR) polymorphism in the 3; untranslated region of the dopamine transporter gene (DAT1) and eating disorders with binge-eating behaviour. METHODS: The subjects were 90 female Japanese patients with eating disorders diagnosed using DSM-IV; they were compared with 115 healthy female controls. Genomic DNA was extracted from whole blood, and standard polymerase chain reaction testing was performed. We compared the frequencies of a short allele (7 or 9 repeats) and a long allele (10 or 11 repeats) in both groups. RESULTS: In the group who had an eating disorder with binge-eating behaviour, the frequency of a short allele was significantly higher compared with the control group. CONCLUSION: It seems plausible that the association between the DAT1 VNTR and binge-eating behaviour indicates that dysregulation of dopamine reuptake may act as a common pathophysiologic mechanism in eating disorders with binge-eating behaviour and in disorders related to substance use.