A novel Romani microdeletion variant in the promoter sequence of ASS1 causes citrullinemia type I

Serum extracellular vesicle-derived ASS1 is a promising predictor for the occurrence of HEV-ALF

Development of biomarkers for predicting the occurrence of hepatitis E virus related-acute liver failure (HEV-ALF) is conducive to prevention and early intervention. Serum samples from 250 HEV-ALF patients, 250 patients with acute hepatitis E (AHE) and 250 health controls (HCs) were collected. We assessed the predictive ability of extracellular vesicle (EV)-derived argininosuccinate synthase 1 (ASS1) levels for HEV-ALF occurrence. Serum EVs were successfully isolated. EV-derived ASS1 levels in the HEV-ALF patients were significantly higher than those in the AHE patients and HCs. In HEV-ALF patients, EV-derived ASS1 levels were positively correlated with the number of failed organs and disease progression. The logistical regression showed that EV-derived ASS1 level is an independent risk factor for HEV-ALF, and orthogonal partial least squares discriminant analysis (OPLS-DA) also suggested that EV-derived ASS1 level has high predictive capability. Besides, the area under the curve (AUC) of EV-derived ASS1 level to predict HEV-ALF occurrence was 0.728 (0.684-0.772) with the sensitivity and specificity being 72.80% and 64.80%, which had a high decision-making ability. Furthermore, there existed no significant difference between the age ≥60 and age <60 groups in EV-derived ASS1 levels. Serum EV-derived ASS1 level is a promising predictor for the occurrence of HEV-ALF.

Clinical, laboratory data and outcomes of 17 Iranian citrullinemia type 1 patients: Identification of five novel ASS1 gene mutations

Citrullinemia type 1 is an autosomal recessive metabolic disease caused by ASS1 gene mutations encoding argininosuccinic acid synthetase enzyme which is within the pathway of arginine and nitric oxide biosynthesis. Disease confirmation was done by ASS1 gene mutation analysis using next-generation sequencing, DNA Sanger sequencing. The study group was 17 citrullinemia type 1 patients from 10 unrelated families referred to Iranian National Society for Study on Inborn Errors of Metabolism's clinic between 2008 and 2020. Clinical, laboratory, and molecular data were retrospectively evaluated. Eleven different ASS1 gene mutations were detected in 13 (76%) of 17 neonatal, three (18%) of 17 late infantile, and one (6%) of 17 asymptomatic patients. Severe developmental delay and intractable seizures despite metabolic control was outcome of neonatal form survivor. Two late infantile form patients live metabolically controlled with quite normal performance. DNA mutations are as follows: seven missense, one nonsense, and two insertion/deletion mutations in 12, two, and three patients, respectively. Five novel mutations were detected including a homozygous GG deletion in exon 12 (c.790_791delGG;p.Gly264Profs*3) and a homozygous mutation in exon 7 (c.440C>T; p.Met147Thr), both causing infantile (late onset) form; a homozygous mutation in exon 6 (c.1130T>C; p.Met376Thr) causing neonatal form; two compound heterozygote mutations in exon 14 (c.1167_1168insC:p.Gly390Argfs*22& c.1186T>A; p.Ser396Thr) causing asymptomatic form. Five (38%) patients with classic neonatal form had mutation in exon 14 of ASS1 (c.1168G>A; p.Gly390Arg). Classic neonatal was the most common form of disease in Iranian-studied patients and homozygote c.1168G>A was the most frequent ASS1 gene mutation. Global neonatal screening for citrullinemia type 1 in Iran is recommended and certain mutations can be used for screening severe form in this population.