Improved diagnostics by exome sequencing following raw data reevaluation by clinical geneticists involved in the medical care of the individuals tested.

PURPOSE: Reanalysis of exome sequencing data when results are negative may yield additional diagnoses. We sought to estimate the contribution of clinical geneticists to the interpretation of sequencing data of their patients. METHODS: The cohort included 84 probands attending a tertiary genetics institute (2015-2018) with a nondiagnostic result on clinical exome sequencing performed in one of five external laboratories. The raw data were uploaded to the Emedgene bioinformatics and interpretation platform for reanalysis by a team of two clinical geneticists, the geneticist directly involved in the patient's care, and a bioinformatician. RESULTS: In ten probands (11.9%), a new definitive diagnosis was reached based on genes that were known to be associated with the phenotype at the time the original report was issued. The main reasons for a negative exome result were incorrect interpretation of the clinical context and absence of OMIM entry. Pathogenic variants in genes with previously unknown gene-disease associations were discovered to be causative in three probands. In total, new diagnoses were established in 13/84 individuals (15.5%). CONCLUSION: Direct access to complete clinical data and shortening of time to including gene-phenotype associations in databases can assist the analytics team and reduce the need for additional unnecessary tests.

A de novo GABRA2 missense mutation in severe early-onset epileptic encephalopathy with a choreiform movement disorder.

BACKGROUND: Early-onset epileptic encephalopathy (EOEE) is a severe convulsive disorder with a poor developmental prognosis. Although it has been associated with mutations in a number of genes, the fact that there is a large proportion of patients who remain undiagnosed suggests that there are many more still-unknown genetic causes of EOEE. Achieving a genetic diagnosis is important for understanding the biological basis of the disease, with its implications for treatment and family planning. METHODS: Whole-exome sequencing was performed in a family of Ashkenazi Jewish origin in which a male infant was diagnosed with EOEE. There was no family history of a similar neurologic disease. The patient had extreme hypotonia, neonatal hypothermia, choreiform movements, and vision impairment in addition to the convulsive disorder. RESULTS: A de novo heterozygous missense mutation, c.1003A > C, p.Asn335His, was identified in a conserved domain of GABRA2. GABRA2 encodes the α2 subunit of the GABAA receptor. CONCLUSIONS: In the context of previous reports of an association of de novo mutations in genes encoding different subunits of the GABAA receptor (GABRB1, GABRA1, GABRG2, GABRB3) with autosomal dominant epileptic disorders, we conclude that a de novo mutation in GABRA2 is likely to cause autosomal dominant EOEE accompanied by a movement disorder and vision impairment.

Expanding the panel of MEFV mutations for routine testing of patients with a clinical diagnosis of familial Mediterranean fever.

BACKGROUND: Since the identification of the MEFV gene 198 mutations have been identified, not all of which are pathologic. The screening methods used in Israel to test patients suspected of having FMF include a kit that tests for the five main mutations (M694V, V726A, M680Ic/g, M694I, E148Q), and the sequencing of MEFV exon 10 in combination with restriction analysis for detecting additional mutations OBJECTIVES: To determine the contribution of testing Ifor five additional mutations - A744S, K695R, M680Ic/t, R761H and P369S - to the molecular diagnosis of patients clinically suspected of having FMF. METHODS: A total of 1637 patients were tested for FMF mutations by sequencing exon 10 and performing restriction analysis for mutations E148Q and P369S. RESULTS: Nearly half the patients (812, 49.6%) did not have any detectable mutations, 581 (35.5%) had one mutation, 241 (14.7%) had two mutations, of whom 122 were homozygous and 119 compound heterozygous, and 3 had three mutations. Testing for the additional five mutations enabled us to identify 46 patients who would have been missedby the molecular diagnosis kit and 22 patients in whom only one mutation would have been found. Altogether, 4.3%of the patients would not have been diagnosed correctly had only the kit that tests for the five main mutations been used. CONCLUSIONS: This study suggests that testing for the additional five mutations as well as the five main mutations in patients with a clinical presentation of FMF adds significantly to the molecular diagnosis of FMF in the Israeli population.