A novel EXT2 mutation in a consanguineous family with severe developmental delay, microcephaly, seizures, feeding difficulties, and osteopenia extends the phenotypic spectrum of autosomal recessive EXT2-related syndrome (AREXT2).

We report a consanguineous family where 2 boys presented with developmental delay, hypotonia, microcephaly, seizures, gastro-intestinal abnormalities, osteopenia, and neurological regression. Whole exome sequencing performed in one of the boys revealed the presence of a novel homozygous missense variant in the EXT2 gene: c.11C > T (p.Ser4Leu). Segregation analysis by Sanger sequencing confirmed homozygous by descent autosomal recessive transmission of this mutation. Another family was previously reported with homozygous mutations in this gene in four siblings affected with a nearly similar clinical condition (Farhan et al., 2015). We discuss the similarities and differences between the two syndromes and propose AREXT2 as a new acronym for EXT2-related diseases.

Dravet Syndrome in Lebanon: First Report on Cases with SCN1A Mutations.

Dravet syndrome, also known as severe myoclonic epilepsy in infancy, is a rare disease characterized by the appearance of different types of seizures in a healthy baby, triggered by various factors and stressful events. We report 8 Lebanese cases referred for molecular analysis of the SCN1A gene. Results were positive in 7 cases and revealed de novo variants at the heterozygous state in different exons of the gene for all except one, where the variant was intronic. Four variants were novel. Confirmation of Dravet syndrome is important for a better follow-up and treatment, preventing the occurrence of status epilepticus and severe neurological deterioration.

Contribution of next generation sequencing in pediatric practice in Lebanon. A Study on 213 cases.

BACKGROUND: According to the Catalogue of Transmission Genetics in Arabs, less than half of diseases reported in Lebanese patients are mapped. In the recent years, Next Generation Sequencing (NGS) techniques have significantly improved clinical diagnosis, compared to traditional sequencing methods. METHODS: A total of 213 analyses by NGS (167 by whole exome sequencing (WES) and 46 by multigene panels tests) were performed on pediatric patients across different regions of Lebanon over a period of two years (December 2015-December 2017). RESULTS: Neurological disorders were the most frequent referral demand for both WES and gene panels (122/213). Pathogenic, likely pathogenic, or variants of unknown significance were identified in 69.5% of the WES and panel patients combined. Over half of the patients with such variants had an autosomal recessive disorder. A definite molecular diagnosis (pathogenic or likely pathogenic variants) was achieved in 34.1% and 47.8% of the patients studied by WES and the multigene panels, respectively. Thirty-three novel variants were found in the cases that were molecularly solved; 26 of these being identified by WES and seven by the multigene panels. In three consanguineous families, autosomal recessive inheritance of genes previously reported as showing dominant inheritance patterns were found. Biallelism was found in six cases, digenism in four cases, and one case was trigenic. CONCLUSION: Our study thus suggests that NGS tools are valuable for an improved clinical diagnosis, and highlights that the increased adoption of such techniques will significantly further improve our understanding of the genetic basis of inherited diseases in Lebanon.

A 56-year-old female patient with facio-oculo-acoustico-renal syndrome (FOAR) syndrome. Report on the natural history and of a novel mutation.

The facio-oculo-acoustico-renal syndrome (FOAR) is a rare autosomal recessive syndrome characterized by the presence of dysmorphic facial features, ocular anomalies, sensorineural hearing loss, and proteinuria. Diaphragmatic hernia, exomphalos, absent or abnormal corpus callosum, and myopia, can also be part of the syndrome. The disorder is caused by mutations of the LRP2 gene located on chromosome 2q23.3-q31.1. We hereby report the case of a 56-year-old female patient with typical FOAR features. Molecular study of the LRP2 gene revealed the presence of a novel splice-site mutation. In addition to what was reported in FOAR syndrome, this patient had a megadolichocolon complicated by a volvulus and a late-onset renal failure which necessitated hemodyalisis and renal transplantation. Reporting aging patients with genetic syndromes will provide information about their special needs and lead to improvements in their follow-up.