Analysis of ASS1 gene in ten unrelated middle eastern families with citrullinemia type 1 identifies rare and novel variants.

BACKGROUND: Citrullinemia type 1 (CTLN1) is a rare autosomal recessive disease caused by argininosuccinate synthetase (ASS) deficiency. Manifestations vary from the acute neonatal or "classic" form to a milder, late-onset, or "unconventional" form. To date, more than 93 variants in the ASS1 gene located on chromosome 9q43.11 (OMIM #215700) are reportedly responsible for CTLN1. Their incidence and distribution vary according to geographic origins and ethnicity, and a correlation, although not clearly delineated, has been established between the genotype and the phenotype of the disease. Though, in the Middle East, national descriptions of CTLN1 are still lacking. METHODS: A total of ten unrelated Middle Eastern families, five Lebanese, two Syrians, and three Iraqis with citrullinemia index cases, were included in this study. Upon informed consent, DNA was extracted from the whole blood of the index patients as well as their parents and siblings. Genetic analysis was carried out by Sanger sequencing of the ASS1 gene. RESULTS: Seven different variants were identified. Two novel variants, c.286C>A (p.(Pro96Thr), RNA not analyzed) in exon 5 and deletion c.685_688+6del(p.(Lys229Glyfs*4), RNA not analyzed) in exon 10, were found in one Lebanese and one Syrian family, respectively, and were correlated with early-onset and severe clinical presentation. Five other known variants: c.535T>C (p.(Trp179Arg), RNA not analyzed) in exon 8, c.787G>A (p.(Val263Met), RNA not analyzed) in exon 12, c.847G>A (p.(Glu283Lys), RNA not analyzed) in exon 13, c.910C>T (p.(Arg304Trp), RNA not analyzed) in exon 13, and c.1168G>A (p.(Gly390Arg), RNA not analyzed) in exon 15, were found in Lebanese, Syrian, and Iraqi families, and were associated with diverse clinical presentations. CONCLUSION: Two novel variants and five known variants were found in a total of ten unrelated Middle Eastern families.

Neuroblastoma Amplified Sequence (NBAS) mutation in recurrent acute liver failure: Confirmatory report in a sibship with very early onset, osteoporosis and developmental delay.

BACKGROUND: Recently, biallelic mutations in the Neuroblastoma Amplified Sequence NBAS gene have been identified in ten patients that present recurrent acute liver failure (RALF) in early infancy. In addition to severe liver dysfunction, some of these individuals also suffered from other comorbidities including cardiomyopathy, neurologic phenotypes and gastrointestinal immune defects. Here we report on a consanguineous Lebanese family with three siblings affected by RALF. Of note, neonatal spontaneous fractures, developmental delay, prominent eyes, generalized hirsutism, gum hypertrophy, and hepato-splenomegaly ​were also present. METHODS: Whole-genome SNP genotyping in all the patients, followed by exome sequencing was performed in one of the affected siblings. RESULTS: A homozygous c.409C > T (p.Arg137Trp) missense mutation in NBAS was identified in all patients. CONCLUSION: Overall, our findings confirm the involvement of NBAS in the pathogenesis of this condition characterized by severe liver dysfunction and help expand its phenotypical spectrum.

Cost-benefit analysis of G6PD screening in Lebanese newborn males.

INTRODUCTION: G6PD deficiency is one of the most prevalent genetic diseases in Lebanon (1% in Lebanese males). Easy and effective screening methods exist to detect this deficiency early in newborns. OBJECTIVE: To assess the cost-effectiveness of G6PD deficiency screening in the routine work-up of every male newborn in Lebanon. METHODS: Of 299 babies with G6PD deficiency detected between 1999 and 2004, 139 (46.5%) were located, contacted, and surveyed for their experience of acute anemia crises. RESULTS: A previous community survey had indicated a 77.8% risk for an acute anemia crisis necessitating hospitalization in unscreened patients, most often associated with consuming fava beans raw or in combination products. In contrast, only 5 (3.8%) of the 139 screened G6PD-deficient babies had ever developed a severe acute anemia crisis. The risk for hospitalization following a crisis had thus been reduced by 95% among patients screened for G6PD deficiency, compared to those unscreened. The estimated mean cost of each hospitalization, which lasts on average 7 days, is 1450 USD. The cost of screening is about 3 USD. The analysis indicates that, given the current prevalence of the deficiency and the reduction in hospitalization rates associated with knowing one's status, the cost of systematic screening is about 2.58 times lower than that of anemia-related hospitalizations in an unscreened population. CONCLUSION: The efficiency of routinely testing evidenced here supports changes in screening policies for boys.

Prevalence of G6PD deficiency and knowledge of diagnosis in a sample of previously unscreened Lebanese males: clinical implications.

The incidence of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Lebanon is estimated at 10 per 1,000 in men and 0.4 per 1,000 in women. A community-based cluster sampling survey was conducted in 15 villages in all areas in Lebanon. The survey found 36 cases of G6PD deficiency among 3,000 men aged 14 years and above, yielding a cumulative incidence rate of 12 per 1,000. Of those 36 cases, 28 (77.8%) knew of their problem since they had already suffered at least one severe anaemia crisis in their childhood following the ingestion of raw green fava beans. The remaining 22.2% were not aware at all of their defect. These findings confirm that G6PD is a common genetic problem in Lebanon. The efficiency of early screening programmes in terms of preventing severe, at times potentially lethal, haemolytic crises is currently being investigated.

Transcription levels of Pseudomonas aeruginosa exotoxin a gene and severity of symptoms in patients with otitis externa.

Polymerase chain reaction (PCR)-based detection and transcription of the gene encoding a potent virulence factor, the exotoxin A, were done on 32 isolates of Pseudomonas aeruginosa belonging to 23 genotypes. These isolates were obtained from 22 patients who were admitted to the emergency room in a medical center during a 5-month period with the diagnosis of either unilateral or bilateral otitis externa. Patients showed symptoms that ranged from mild to severe. PCR amplification of a 396-bp fragment of the gene encoding the exotoxin A was done on extracted DNA. Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) was performed on extracted RNA to detect exotoxin A gene mRNA transcripts. Quantitation of RT-PCR amplicons from P. aeruginosa isolates associated with mild and severe symptoms was determined by end-point titration of c-DNA and scanning of amplicons with the Storm Gel and Blot Imaging System. Data have shown that all of the 32 isolates of P. aeruginosa carry the exotoxin A gene, and all isolates with the exception of two had the exotoxin A transcription demonstrated by the production of a 396-bp amplicon from RT-PCR-amplified RNA. The remaining two isolates amplified fragments that were slightly smaller than the expected size. Additional studies are needed to characterize these two mRNA transcripts. Transcription levels of exotoxin A gene associated with severe symptoms were significantly more elevated than those associated with mild to moderate symptoms. Studies are under way to determine expression of P. aeruginosa exotoxin A by detecting quantitatively levels of the translated exotoxin A protein produced by isolates associated with severe and mild to moderate symptoms.