An uncommon case of arthrogryposis, renal dysfunction, and cholestasis (ARC) syndrome and review of the renal involvement: Questions

Mild Phenotype of Arthrogryposis, Renal Dysfunction, and Cholestasis Syndrome 1 Caused by a Novel VPS33B Variant

The arthrogryposis, renal dysfunction, and cholestasis syndrome (ARCS) is an autosomal recessive multisystem disease caused by variants in VPS33B or VIPAS39. The classical presentation includes congenital joint contractures, renal tubular dysfunction, cholestasis, and early death. Additional features include ichthyosis, central nervous system malformations, platelet dysfunction, and severe failure to thrive. We studied three patients with cholestasis, increased aminotransferases, normal gamma-glutamyl transferase, and developmental and language delay. Whole exome sequencing analysis identified VPS33B variants in all patients: patients 1 and 2 presented a novel homozygous variant at position c.1148T>A. p.(Ile383Asn), and patient 3 was compound heterozygous for the same c.1148T>A. variant, in addition to the c.940-2A>G. variant. ARCS is compatible with the symptomatology presented by the studied patients. However, most patients that have been described in the literature with ARCS had severe failure to thrive and died in the first 6 months of life. The three patients studied here have a mild ARCS phenotype with prolonged survival. Consequently, we believe that the molecular analysis of the VPS33B and VIPAS39 should be considered in patients with normal gamma-glutamyl transferase cholestasis.

Two novel mutations in VPS33B gene cause a milder ARC syndrome with prolonged survival in a 12-year-old patient: Case report

Arthrogryposis-renal dysfunction-cholestasis (ARC) syndrome is a rare autosomal recessive disease caused by VPS33B and VIPAR gene mutations. The main clinical manifestations are congenital joint contracture, renal dysfunction mainly characterized by distal renal tubular dysfunction, and low glutamyltransferase cholestasis. Most patients with ARC die within 2 years of birth. Here, we report the case of a 12-year-old girl with an ARC phenotype who experienced long-term survival with only mild clinical symptoms. We detected two new heterozygous mutation sites of the VPS33B gene in this child, c.1081C > T (p.GLN361X, 257) and c.244T > C (p.Cys82Arg), through the gene detection technique; the tertiary structure of the protein was predicted by using the SWISS-model. We further reviewed the literature and summarized the clinical manifestations and gene loci of 19 ARC syndrome patients with long-term survival reported so far.

A New Aberration in the VPS33B Gene Leads to Full-Symptom ARCS1

BACKGROUND ARCS1 is an acronym for arthrogryposis, renal dysfunction, and cholestasis. It is a congenital malfunction with autosomal recessive inheritance, and, unfortunately, its prognosis is still poor. It is believed that VPS33B is altered in 75% of cases and that the VIPAR gene is altered in approximately 25% of them. CASE REPORT An affected child was born from the first pregnancy of 26-year-old mother and a 30-year-old father with no previous medical history and no genetic conditions. The first clinical symptoms were observed at the end of the child's second week of life. The mother reported the child has decreasing body weight and loss of appetite. After admission to the ward, the child was apathetic and sleepy. Symptoms of conjunctivitis, pale and dry skin, and mild face and mild body dysmorphia were observed. CONCLUSIONS Laboratory tests revealed proteinuria of up to 1.36 g/l and glycosuria of up to 28 mmol/l, as well as fluctuating metabolic acidosis. The bilirubin level reached 6.62 mg/dl, along with alkaline phosphatase at 470 U/l. Moreover, hypothyroidism with TSH at 16.71 uU/ml was observed. Because of the co-occurrence of cholestasis and renal dysfunction, molecular testing was done. The 17th exon of VPS33B was sequenced by Sanger DNA sequencing method. To the best of our knowledge, this is the first report of homozygotic mutation c.1235_1236delinsG (p.Pro412ArgfsTer7) in the VPS33B gene. The risk of transfer of the mutation to future descendants was calculated as 25%. Due to the wide landscape of molecular alternation in the 17th exon of the VPS33B gene, we propose using Sanger whole-exon sequencing as a first-choice diagnostic test.