Frequency of inborn errors of metabolism screening for children with unexplained acute encephalopathy at an emergency department.

OBJECTIVE: Our study aimed to estimate the frequency of inborn errors of metabolism (IEMs) in patients presenting with acute encephalopathy-like picture at an emergency department (ED). SUBJECTS AND METHODS: Our study was a prospective observational study conducted on 30 patients admitted to the pediatric ED with unexplained acute encephalopathy. The study included 30 children with an age ranging from 1 month to 5 years. All patients were subjected to full history taking, thorough clinical examination, and laboratory investigations including serum ammonia, serum lactate, arterial blood gases, tandem mass spectroscopy, organic acid of urine, cerebrospinal fluid examination to exclude central nervous system infection plus the routine laboratory tests (kidney functions, liver functions, random blood glucose, complete blood picture), and brain imaging computed tomography and/or magnetic resonance imaging brain. RESULTS: Thirty children presented with acute encephalopathy at the ED. All were screened for suspected IEMs. Ten (33.3%) of them was positive in the initial screening test. There were four (13.3%) patients with possible mitochondrial diseases, four (13.3%) patients with possible organic acidemia, one (3.3%) patient with possible urea cycle defect, and one (3.3%) patient with possible nonketotic hyperglycinemia. CONCLUSION: Any case of unexplained acute encephalopathy presenting to the ED should be investigated for suspected IEM, especially in high-risk families, as early interventions will lead to improved outcome.

Mutations in KIF7 link Joubert syndrome with Sonic Hedgehog signaling and microtubule dynamics.

Joubert syndrome (JBTS) is characterized by a specific brain malformation with various additional pathologies. It results from mutations in any one of at least 10 different genes, including NPHP1, which encodes nephrocystin-1. JBTS has been linked to dysfunction of primary cilia, since the gene products known to be associated with the disorder localize to this evolutionarily ancient organelle. Here we report the identification of a disease locus, JBTS12, with mutations in the KIF7 gene, an ortholog of the Drosophila kinesin Costal2, in a consanguineous JBTS family and subsequently in other JBTS patients. Interestingly, KIF7 is a known regulator of Hedgehog signaling and a putative ciliary motor protein. We found that KIF7 co-precipitated with nephrocystin-1. Further, knockdown of KIF7 expression in cell lines caused defects in cilia formation and induced abnormal centrosomal duplication and fragmentation of the Golgi network. These cellular phenotypes likely resulted from abnormal tubulin acetylation and microtubular dynamics. Thus, we suggest that modified microtubule stability and growth direction caused by loss of KIF7 function may be an underlying disease mechanism contributing to JBTS.

Clinical and genetic characterization of Chanarin-Dorfman syndrome patients: first report of large deletions in the ABHD5 gene.

BACKGROUND: Chanarin-Dorfman syndrome (CDS) is a rare autosomal recessive disorder characterized by nonbullous congenital ichthyosiform erythroderma (NCIE) and an intracellular accumulation of triacylglycerol (TG) droplets in most tissues. The clinical phenotype involves multiple organs and systems, including liver, eyes, ears, skeletal muscle and central nervous system (CNS). Mutations in ABHD5/CGI58 gene are associated with CDS. METHODS: Eight CDS patients belonging to six different families from Mediterranean countries were enrolled for genetic study. Molecular analysis of the ABHD5 gene included the sequencing of the 7 coding exons and of the putative 5' regulatory regions, as well as reverse transcript-polymerase chain reaction analysis and sequencing of normal and aberrant ABHD5 cDNAs. RESULTS: Five different mutations were identified, four of which were novel, including two splice-site mutations (c.47+1G>A and c.960+5G>A) and two large deletions (c.898_*320del and c.662-1330_773+46del). All the reported mutations are predicted to be pathogenic because they lead to an early stop codon or a frameshift producing a premature termination of translation. While nonsense, missense, frameshift and splice-site mutations have been identified in CDS patients, large genomic deletions have not previously been described. CONCLUSIONS: These results emphasize the need for an efficient approach for genomic deletion screening to ensure an accurate molecular diagnosis of CDS. Moreover, in spite of intensive molecular screening, no mutations were identified in one patient with a confirmed clinical diagnosis of CDS, appointing to genetic heterogeneity of the syndrome.