A Novel TTC19 Mutation in a Patient With Neurological, Psychological, and Gastrointestinal Impairment.

Mitochondrial complex III deficiency nuclear type 2 is an autosomal-recessive disorder caused by mutations in TTC19 gene. TTC19 is involved in the preservation of mitochondrial complex III, which is responsible for transfer of electrons from reduced coenzyme Q to cytochrome C and thus, contributes to the formation of electrochemical potential and subsequent ATP generation. Mutations in TTC19 have been found to be associated with a wide range of neurological and psychological manifestations. Herein, we report on a 15-year-old boy born from first-degree cousin parents, who initially presented with psychiatric symptoms. He subsequently developed progressive ataxia, spastic paraparesis with involvement of caudate bodies and lentiform nuclei with cerebellar atrophy. Eventually, the patient developed gastrointestinal involvement. Using whole-exome sequencing (WES), we identified a novel homozygous frameshift mutation in the TTC19 gene in the patient (NM_017775.3, c.581delG: p.Arg194Asnfs*16). Advanced genetic sequencing technologies developed in recent years have not only facilitated identification of novel disease genes, but also allowed revelations about novel phenotypes associated with mutations in the genes already linked with other clinical features. Our findings expanded the clinical features of TTC19 mutation to potentially include gastrointestinal involvement. Further functional studies are needed to elucidate the underlying pathophysiological mechanisms.

A novel splice site mutation in WAS gene in patient with Wiskott-Aldrich syndrome and chronic colitis: a case report.

BACKGROUND: Wiskott-Aldrich syndrome is an X-linked recessive immunodeficiency due to mutations in Wiskott-Aldrich syndrome (WAS) gene. WAS gene is encoded for a multifunctional protein with key roles in actin polymerization, signaling pathways, and cytoskeletal rearrangement. Therefore, the impaired protein or its absence cause phenotypic spectrum of the disease. Since identification of novel mutations in WAS gene can help uncover the exact pathogenesis of Wiskott-Aldrich syndrome, the purpose of this study was to investigate disease causing-mutation in an Iranian male infant suspicious of this disorder. CASE PRESENTATION: The patient had persistent thrombocytopenia from birth, sepsis, and recurrent gastrointestinal bleeding suggestive of both Wiskott-Aldrich syndrome and chronic colitis in favor of inflammatory bowel disease (IBD). To find mutated gene in the proband, whole exome sequencing was performed for the patient and its data showed a novel, private, hemizygous splice site mutation in WAS gene (c.360 + 1G > C). CONCLUSIONS: Our study found a novel, splice-site mutation in WAS gene and help consider the genetic counselling more precisely for families with clinical phenotypes of both Wiskott-Aldrich syndrome and inflammatory bowel disease and may suggest linked pathways between these two diseases.

Mutation analysis of the CTNS gene in Iranian patients with infantile nephropathic cystinosis: identification of two novel mutations.

Nephropathic cystinosis is an inherited lysosomal transport disorder caused by mutations in the CTNS gene that encodes for a lysosomal membrane transporter, cystinosin. Dysfunction in this protein leads to cystine accumulation in the cells of different organs. The accumulation of cystine in the kidneys becomes apparent with renal tubular Fanconi syndrome between 6 and 12 months of age and leads to renal failure in the first decade of life. The aim of this study was to analyze the CTNS mutations in 20 Iranian patients, from 20 unrelated families, all of whom were afflicted with infantile nephropathic cystinosis. In these patients, seven different mutant alleles were found, including two new mutations, c.517T>C; p.Y173H and c.492_515del, that have not been previously reported. In addition, we observed that c.681G>A, the common Middle Eastern mutation, was the most common mutation in our patients. Moreover, a new minisatellite or variable number of tandem repeat marker (KX499495) was identified at the CTNS gene. Seven different alleles were found for this marker, and its allele frequency and heterozygosity degree were calculated in cystinosis patients and healthy individuals.