A Deeper Insight into COL4A3, COL4A4, and COL4A5 Variants and Genotype-Phenotype Correlation of a Turkish Cohort with Alport Syndrome.

Introduction: Alport syndrome (AS) is an inherited, rare, progressive kidney disease that affects the eye and ear physiology. Pathogenic variants of COL4A5 account for 85% of all cases, while COL4A3 and COL4A4 account for the remaining 15%. Methods: Targeted next-generation sequencing of the COL4A3, COL4A4, and COL4A5 genes was performed in 125 Turkish patients with AS. The patients were compared to 45 controls and open-access population data. Results: The incidence of AS variants in patients was found as 21.6%. 27 variants were identified as pathogenic/likely pathogenic, 28 as variant of uncertain significance, and 52 as benign/likely benign. We also found 31 novel variants (14 in COL4A3, 6 in COL4A4, and 11 in COL4A5) of which 27 were classified as pathogenic/likely pathogenic. Pathogenic/likely Pathogenic variants were most commonly found in the COL4A5 gene, consistent with the literature. This study contributed novel variants associated with AS to the literature. Conclusion: Genetic testing is a crucial part for the diagnosis and management of AS. Studies on the genetic etiology of AS are limited for the Turkish population. We believe that this study will contribute to the literature and the clinical decision-making process of patients with AS and emphasize the importance of genetic counseling.

Genetic and Clinical Characteristics of Patients with Vitamin D Dependent Rickets Type 1A

Objective: Vitamin D dependent rickets type 1A (VDDR1A) is an autosomal recessive disorder caused by mutations in the 1α-hydroxylase gene (CYB27B1). As it may be confused with nutritional rickets and hypophosphatemic rickets, genetic analysis is important for making a correct diagnosis. Methods: We analysed genomic DNA from 11 patients from eight different Turkish families. The patients were recruited for our studies if they presented with a diagnosis of VDDR. Results: The mean ± standard deviation age at diagnosis was 13.1±7.4 months. Seven patients had mild hypocalcemia at presentation while four patients had normal calcium concentrations. All patients underwent CYP27B1 gene analysis. The most prevalent mutation was the c.195 + 2T>G splice donor site mutation, affecting five out of 11 patients with VDDR1A. Two patients from the fourth family were compound heterozygous for c.195 + 2T>G and c.195 + 2 T>A in intron-1. Two patients, from different families, were homozygous for a previously reported duplication mutation in exon 8 (1319_1325dupCCCACCC, Phe443Profs*24). One patient had a homozygous splice site mutation in intron 7 (c.1215 + 2 T>A) and one patient had a homozygous mutation in exon 9 (c.1474 C>T). Conclusion: Intron-1 mutation was the most common mutation, as previously reported. All patients carrying that mutation were from same city of origin suggesting a "founder" or a "common ancestor" effect. VDDR1A should definitely be considered when a patient with signs of rickets has a normal 25-OHD level or when there is unresponsiveness to vitamin D treatment.

Glycogen storage disease type 0 due to a novel frameshift mutation in glycogen synthase 2 (GYS2) gene in a child presenting with fasting hypoglycemia and postprandial hyperglycemia.

Hacihamdioglu B, Özgürhan G, Çaran B, Meydan-Aksanli E, Keskin E. Glycogen storage disease type 0 due to a novel frameshift mutation in glycogen synthase 2 (GYS2) gene in a child presenting with fasting hypoglycemia and postprandial hyperglycemia. Turk J Pediatr 2018; 60: 581-583. Glycogen storage disease type 0 (GSD0) has been considered a rare disorder, it is characterized with ketotic hypoglycemia after prolonged fasting and postprandial hyperglycemia. Herein, we report a novel mutation in the glycogen synthase 2 gene in a Turkish child, as well as her clinical characteristics and 12-month follow-up. We evaluated a 5-year-old girl for asymptomatic fasting ketotic hypoglycemia with postprandial hyperglycemia diagnosed with glycogen storage disease type 0. We identified a novel frameshift mutation, c.1081delA (p.Thr361Glnfs*2) in exon 8 on glycogen synthase 2 gene. Children with GSD0 may have a mild phenotype and GSD0 may be underdiagnosed due to subclinical or asymptomatic hypoglycemia. The diagnosis of GSD0 should be considered in a child with ketotic fasting hypoglycemia with postprandial hyperglycemia but without hepatomegaly.

Frequency of mutations in Mediterranean fever gene, with gender and genotype-phenotype correlations in a Turkish population.

Familial Mediterranean fever (FMF) is the most common hereditary inflammatory periodic disease, characterized by recurrent episodes of fever, abdominal pain, synovitis and pleurisy. The aim of this study was to determine the frequency and distribution of Mediterranean fever (MEFV) gene mutations and to investigate the clinical characteristics and genotype-phenotype correlation in patients with FMF in Aydin, a province in western Anatolia, Turkey. Therefore, we retrospectively analysed MEFV gene mutations in 383 patients with suspected FMF and the clinical features of 327 among them. The MEFV gene mutations were investigated using the reverse dot-blot hybridization technique. We detected 26 different genotypes and 11 different mutations. The most common mutations in our cohort were p.M694V (41.15%), p.E148Q (20.35%), p.M680I(G/C) (12.39%) and p.R761H (9.73%). Abdominal pain (86.2%), fever (80.7%), arthralgia (57.2%), vomiting (36.1%), arthritis (34.6%), fatigue (31.5%), anorexia (22.9%) and chest pain (19.0%) were the most prevalent clinical features in our patients. This is the first study from Aydin in which the distribution of MEFV gene mutations and clinical features were evaluated in patients with FMF. We found that the most common mutation was p.M694V in our region, while the frequency of the p.R761H mutation was higher compared to other regions of Turkey with respect to extracted data from previous similar studies. Presented results supported the clinical findings in the literature that the homozygous p.M694V and compound heterozygous genotype were associated with more severe courses in FMF patients.