Treatment of hepatitis C in children with direct-acting antiviral drugs.

The primary purpose of treating chronic hepatitis C (HCV) is to prevent the development of liver fibrosis, cirrhosis, and cancer. In the last decade, direct-acting antiviral medicine (DAA) has been approved to treat children with HCV. This treatment has a higher efficacy, shorter duration, and milder side effects than the previously approved treatment. In this review, it is recommended to track down children who might be infected with HCV to enhance early treatment to prevent transmission of the virus and the possible complications.

Paediatric hepatitis B and hepatitis C virus infections: An observational study of a Danish cohort.

AIM: The aim of this study was to describe the epidemiological and clinical characteristics in children with either chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection in Denmark. METHODS: In this observational study, children and adolescents with either chronic HBV or HCV infection followed at the largest paediatric departments in Denmark between 2001 and 2013 were included. Data collection included as well epidemiological data as clinical data like virus genotype, viral load, serological markers, liver biochemistry, liver elastography and histology if available. RESULTS: The study included 131 children. None of the patients had decreased liver function or end-stage liver disease during follow-up. Ten of the 18 children who underwent liver biopsy had signs of fibrosis. Thirteen (11%) children with HBV and one (7%) child with HCV received treatment. Different indications and different treatment regimens were used. CONCLUSION: This study confirms that chronic HBV and HCV infections are often mild diseases during childhood. Nevertheless, children are at higher risk of serious liver disease early in life because of the early time of infection and probably also because of the high viral loads.

A Novel Synonymous Variant in the AVP Gene Associated with Autosomal Dominant Familial Neurohypophyseal Diabetes Insipidus Causes Partial RNA Missplicing.

OBJECTIVE: Autosomal dominant familial neurohypophyseal diabetes insipidus (adFNDI) is characterized by severe polyuria and polydipsia and is caused by variations in the gene encoding the AVP prohormone. This study aimed to ascertain a correct diagnosis, to identify the underlying genetic cause of adFNDI in a Swedish family, and to test the hypothesis that the identified synonymous exonic variant in the AVP gene (c.324G>A) causes missplicing and endoplasmic reticulum (ER) retention of the prohormone. DESIGN/PATIENTS: Three affected family members were admitted for fluid deprivation test and dDAVP (1-deamino-8-d-arginine-vasopressin) challenge test. Direct sequencing of the AVP gene was performed in the affected subjects, and genotyping of the identified variant was performed in family members. The variant was examined by expression of AVP minigenes containing the entire coding regions as well as intron 2 of AVP. METHODS/RESULTS: Clinical tests revealed significant phenotypical variation with both complete and partial adFNDI phenotype. DNA analysis revealed a synonymous c.324G>A substitution in one allele of the AVP gene in affected family members only. Cellular studies revealed both normally spliced and misspliced pre-mRNA in cells transfected with the AVP c.324G>A minigene. Confocal laser scanning microscopy showed collective localization of the variant prohormone to ER and vesicular structures at the tip of cellular processes. CONCLUSION: We identified a synonymous variant affecting the second nucleotide of exon 3 in the AVP gene (c.324G>A) in a family in which adFNDI segregates. Notably, we showed that this variant causes partial missplicing of pre-mRNA, resulting in accumulation of the variant prohormone in ER. Our study suggests that even a small amount of aberrant mRNA might be sufficient to disturb cellular function, resulting in adFNDI.

Novel and recurrent variants in AVPR2 in 19 families with X-linked congenital nephrogenic diabetes insipidus.

Congenital nephrogenic diabetes insipidus (CNDI) is characterized by the reduced ability of renal collecting duct cells to reabsorb water in response to the antidiuretic effect of vasopressin. Chronic polyuria and polydipsia are the hallmarks of the disease. Approximately 90% of all patients with CNDI have X-linked inherited disease caused by variants in the arginine vasopressin receptor 2 (AVPR2) gene. We present genetic findings in 34 individuals from 19 kindreds including one or more family members with CNDI. Coding regions of AVPR2 were sequenced bi-directionally. We identified eight novel disease-causing variants in AVPR2, p.Arg68Alafs*124, p.Ser171Arg, p.Gln174Pro, p.Trp200Arg, p.Gly201Cys, p.Gly220Arg, p.Val226Glu, and p.Gln291Pro in nine kindreds. In all three families with more than one affected individual, the novel variants segregated with the disease. We also identified eight recurrent disease-causing variants, p.Val88Met, p.Leu111Valfs*80, p.Arg113Trp, p.Tyr124*, p.Ser167Leu, p.Thr207Asn, p.Arg247Alafs*12, and p.Arg337* in ten kindreds. Our findings contribute to the growing list of AVPR2 variants causing X-linked CNDI. CONCLUSION: Being a rapid diagnostic tool for CNDI, direct sequencing of AVPR2 should be encouraged in newborns with familial predisposition to CNDI. What is Known: • Disease-causing variants in AVPR2 cause X-linked congenital nephrogenic diabetes insipidus (CNDI). • DNA sequencing of AVPR2 is rapid, facilitates differential diagnosis, early intervention, and genetic diagnosis thus reducing morbidity in CNDI. What is New: • We identified eight novel disease-causing variants in AVPR2: p.Arg68Alafs*124, p.Ser171Arg, p.Gln174Pro, p.Trp200Arg, p.Gly201Cys, p.Gly220Arg, p.Val226Glu, and p.Gln291Pro, thereby adding to the growing list of AVPR2 disease-causing variants and emphasizing the importance of genetic testing in CNDI.

The Novel Ser18del AVP Variant Causes Inherited Neurohypophyseal Diabetes Insipidus by Mechanisms Shared with Other Signal Peptide Variants.

BACKGROUND/AIM: Variability in the severity and age at onset of autosomal dominant familial neurohypophyseal diabetes insipidus (adFNDI) may be associated with certain types of variants in the arginine vasopressin (AVP) gene. In this study, we aimed to describe a large family with an apparent predominant female occurrence of polyuria and polydipsia and to determine the underlying cause. METHODS: The family members reported their family demography and symptoms. Two subjects were diagnosed by fluid deprivation and dDAVP challenge tests. Eight subjects were tested genetically. The identified variant along with 3 previously identified variants in the AVP gene were investigated by heterologous expression in a human neuronal cell line (SH-SY5Y). RESULTS: Both subjects investigated clinically had a partial neurohypophyseal diabetes insipidus phenotype. A g.276_278delTCC variant in the AVP gene causing a Ser18del deletion in the signal peptide (SP) of the AVP preprohormone was perfectly co-segregating with the disease. When expressed in SH-SY5Y cells, the Ser18del variant along with 3 other SP variants (g.227G>A, Ser17Phe, and Ala19Thr) resulted in reduced AVP mRNA, impaired AVP secretion, and partial AVP prohormone degradation and retention in the endoplasmic reticulum. Impaired SP cleavage was demonstrated directly in cells expressing the Ser18del, g.227G>A, and Ala19Thr variants, using state-of-the-art mass spectrometry. CONCLUSION: Variants affecting the SP of the AVP preprohormone cause adFNDI with variable phenotypes by a mechanism that may involve impaired SP cleavage combined with effects at the mRNA, protein, and cellular level.

Induced pluripotent stem cells derived from a patient with autosomal dominant familial neurohypophyseal diabetes insipidus caused by a variant in the AVP gene.

Autosomal dominant familial neurohypophyseal diabetes insipidus (adFNDI) is caused by variants in the arginine vasopressin (AVP) gene. Here we report the generation of induced pluripotent stem cells (iPSCs) from a 42-year-old man carrying an adFNDI causing variant in exon 1 of the AVP gene using lentivirus-mediated nuclear reprogramming. The iPSCs carried the expected variant in the AVP gene. Furthermore, the iPSCs expressed pluripotency markers; displayed in vitro differentiation potential to the three germ layers and had a normal karyotype consistent with the original fibroblasts. This iPSC line is useful in future studies focusing on the pathogenesis of adFNDI.

Late-onset familial neurohypophyseal diabetes insipidus due to a novel mutation in the AVP gene.

OBJECTIVE: Familial neurohypophyseal diabetes insipidus (FNDI) is mainly an autosomal dominant inherited disorder presenting with severe polydipsia and polyuria in early childhood. In this study, we aimed to determine the molecular genetics and clinical characteristics of a large Swedish-Norwegian family presenting with very late-onset autosomal dominant FNDI. PATIENTS: Six probands with a history of developing polyuria and polydipsia during adolescence were studied. MEASUREMENTS: Information on family demography was collected by personal interview with family members. The genetic cause of FNDI was identified by DNA sequencing analysis of the coding regions of the AVP gene. The clinical characteristics were determined by the measurement of basal urine production and osmolality as well as by measurements of concurrent levels of plasma AVP, plasma osmolality, and urine osmolality during fluid deprivation and bolus injection of DDAVP. The integrity of the neurohypophysis was evaluated by magnetic resonance imaging. RESULTS: The mean age of encountering the first clinical symptoms in the family was 14·8 years (range 3-30 years) (n = 17). All six affected subjects investigated were heterozygous for a novel mutation in the AVP gene (g.1848C>T) predicting a p.Pro84Leu substitution in the AVP precursor protein. We found partial deficiency in evoked AVP secretion during fluid deprivation in one subject and complete deficiency in another. The pituitary bright spot was absent in all six affected subjects studied. CONCLUSION: A novel mutation in the AVP gene predicted to cause a neurophysin II dimerization defect is causing surprisingly late onset of FNDI in a large, six generation, Swedish-Norwegian family. The mutation is associated with both complete and partial deficiency in evoked AVP secretion during fluid deprivation in patients who have suffered from FNDI for decades.