Özlem Nalbantoğlu

Novel CYP27B1 Gene Mutations in Patients with Vitamin D-Dependent Rickets Type 1A

The CYP27B1 gene encodes 25-hydroxyvitamin D-1α-hydroxylase. Mutations of this gene cause vitamin D-dependent rickets type 1A (VDDR-IA, OMIM 264700), which is a rare autosomal recessive disorder. To investigate CYP27B1 mutations, we studied 8 patients from 7 unrelated families. All coding exons and intron-exon boundaries of CYP27B1 gene were amplified by PCR from peripheral leukocyte DNA and subsequently sequenced. Homozygous mutations in the CYP27B1 gene were found in all the patients and heterozygous mutations were present in their normal parents. One novel single nucleotide variation (SNV, c.1215 T>C, p.R379R in the last nucleotide of exon 7) and three novel mutations were identified:, a splice donor site mutation (c.1215+2T>A) in intron 7, a 16-bp deletion in exon 6 (c.1022-1037del16), and a 2-bp deletion in exon 5 (c.934_935delAC). Both c.1215 T>C and c.1215+2T>A were present together in homozygous form in two unrelated patients, and caused exon 7 skipping. However, c.1215 T>C alone has no effect on pre-mRNA splicing. The skipping of exon 7 resulted in a shift of downstream reading frame and a premature stop codon 57 amino acids from L380 (p.L380Afs*57). The intra-exon deletions of c.1022-1037del16 and c.934_935delAC also resulted in a frameshift and the creation of premature stop codons at p.T341Rfs*5, and p.T312Rfs*19, respectively, leading to the functional inactivation of the CYP27B1 gene. Clinically, all the patients required continued calcitriol treatment and the clinical presentations were consistent with the complete loss of vitamin D1α-hydroxylase activity. In conclusion, three novel mutations have been identified. All of them caused frameshift and truncated proteins. The silent c.1215 T>C SNV has no effect on pre-mRNA splicing and it is likely a novel SNP. The current study further expands the CYP27B1 mutation spectrum.

Complete Idiopathic Hypogonadotropic Hypogonadism due to Homozygous GNRH1 Mutations in the Mutational Hot Spots in the Region Encoding the Decapeptide

Introduction: Mutations of the human GNRH1 gene are an extremely rare cause of normosmic idiopathic hypogonadotropic hypogonadism (nIHH), with only 6 mutations so far described. Patients: As part of a larger study, families with IHH were screened for mutations in genes known to be associated with IHH. In family 1, a 15-year and 9-month-old boy first presented during infancy with micropenis and bilateral cryptorchidism. His pubic and axillary hair is at stage 4 and 2, respectively. His testes are 1 ml bilaterally, and his stretched penile length is 3.6 cm. In family 2, a 19-year and 2-month-old man was referred because of absence of secondary sexual characteristics. His 13-year and 8-month-old sister did not have any breast development. Results: In 3 patients from 2 independent families we identified GNRH1 mutations. In the proband from family 1, a homozygous 1-base deletion (c.87delA) leading to a frameshift mutation (p.G29GfsX12) was identified. In family 2, the affected siblings had a novel homozygous mutation of c.G92A leading to p.R31H. Conclusion: Both mutations in these families are located in the region encoding the decapeptide and in the loci where the mutations have been described before. Therefore, these areas can be considered as mutational hot spots, indicating priority for routine diagnostic gene mutation analysis.

A novel mutation of AMH in three siblings with persistent Mullerian duct syndrome

Abstract Background: Persistent Mullerian duct syndrome (PMDS) is a rare form of male 46,XY disorder of sex development characterized by the presence of Mullerian duct derivatives in otherwise phenotypically normal males. Aim: To report a novel mutation of the anti-Mullerian hormone (AMH) gene in two of three siblings with PMDS. Cases: A 2-year-old male presented with recurrent left-sided inguinal hernia and absence of right testis. Laparoscopic surgery disclosed Mullerian duct derivates and transverse testicular ectopia. AMH level was found to be low [1.6 ng/mL (normal range 7.4–373.1), 11.42 pmol/L (normal range 52.8–2663.9)]. His 15-year-old and 7-year-old elder brothers were invited, and bilateral undescended testes were noted upon examination. Female reproductive structures were identified during surgery but no transverse testicular ectopia. All cases had 46,XY karyotype. Genetic analyses could be done in two of them and a unique homozygous T to C base substitution was found at position 1591 in the AMH gene. Conclusion: This is the first report of the AMH gene mutation which is referred as p.Y531H (c.1591T>C), which resulted in different phenotypes of PMDS in three siblings.

Genetic Diagnosis Using Whole Exome Analysis in Two Cases with Malignant Osteopetrosis of Infancy

Ad dress for Cor res pon den ce Korcan Demir MD, Dr. Behçet Uz Children’s Hospital, Clinic of Pediatric Endocrinology, İzmir, Turkey Phone: +90 232 412 60 77 E-mail: korcan.demir@deu.edu.tr, korcandemir@gmail.com ©Jo ur nal of Cli ni cal Re se arch in Pe di at ric En doc ri no logy, Pub lis hed by Ga le nos Pub lis hing. Genetic Diagnosis Using Whole Exome Analysis in Two Cases with Malignant Osteopetrosis of Infancy J Clin Res Pediatr Endocrinol 2015;7(4):356-357 DO I: 10.4274/jcrpe.2597

Retinal Ganglion Cell Loss in Children With Type 1 Diabetes Mellitus Without Diabetic Retinopathy

BACKGROUND AND OBJECTIVE Early diabetic retinal changes in children with type 1 diabetes mellitus (T1DM) without diabetic retinopathy (DR) were examined using spectral-domain optical coherence tomography (SD-OCT). PATIENTS AND METHODS Sixty children with T1DM without DR and 60 normal children were enrolled in the study. SD-OCT was used to measure the ganglion cell-inner plexiform layer (GC-IPL) and retinal nerve fiber (RNFL) thicknesses in all participants. RESULTS The GC-IPL thickness was significantly decreased in all quadrants except the superior-nasal quadrant in children with diabetes (P < .05). However, the RNFL thickness in all quadrants was not significantly different between the groups (P > .05). CONCLUSIONS There was a decreased GC-IPL thickness in children with T1DM without DR, suggesting that T1DM has an early neurodegenerative effect on retinal ganglion cells that occurs when the vascular component of DR is absent. SD-OCT may be more useful than ophthalmoscopic evaluation for detecting the earlier retinal structural changes of diabetes. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:473-477.].

Melanocortin-4 Receptor Gene Mutations in a Group of Turkish Obese Children and Adolescents

Objective: Melanocortin-4 receptor (MC4R) mutations are the most common known cause of monogenic obesity. Data regarding MC4R mutations in Turkish subjects are limited. To determine the prevalence of MC4R mutations in a group of Turkish morbid obese children and adolescents. Methods: MC4R was sequenced in 47 consecutive morbidly obese children and adolescents (28 girls and 19 boys, aged 1-18 years) who presented during a one-year period. Inclusion criterion was a body mass index (BMI) ≥120% of the 95th percentile or ≥35 kg/m2. Patients with chronic diseases, Cushing syndrome, hypothyroidism, or suspected syndromes that could cause obesity were excluded. Onset of obesity was before age 10 years in all subjects. Results: Mean age was 13.2±4.1 years, age at onset of obesity 5.1±2.1 years, height standard deviation (SD) score 1.21±0.93, BMI 40.0±8.8 kg/m2, and BMI SD score was 2.72±0.37. One novel (c.870delG) and two previously reported (c.496 G>A, c.346_347delAG) mutations were found in four (8.5%) obese children and adolescents. The novel mutation (c.870delG) was predicted to be a disease-causing frame-shift mutation using in silico analyses. Fasting glucose and lipid levels of the patients with MC4R mutation were normal, but insulin resistance was present in two of the subjects. Six more individuals with MC4R mutation (1 child, 5 adults) were detected following analyses of the family members of affected children. Conclusion: MC4R mutations are frequently found in morbid obese Turkish children and adolescents.

Metabolic Control and Periodontal Treatment Decreases Elevated Oxidative Stress in the Early Phases of Type 1 Diabetes Onset

OBJECTIVE Recently, increasing concern has been focused on the contribution of oxidative stress in the pathology of periodontal disease and diabetes mellitus. Firstly, the present study aimed to analyze gingival crevicular fluid (GCF), salivary, and serum oxidative status in children with type 1 diabetes mellitus (T1DM) at diagnosis and systemically healthy children with and without gingivitis. Additionally, the diabetic patients were reevaluated after diabetes and periodontal treatment. DESIGN The study groups were composed of 32 T1DM patients at diagnosis, and age- and gender-matched thirty-six systemically healthy children with (G) and without (H) gingivitis. The diabetic patients who took insulin therapy (1.5 units/kg/day totally) and periodontal treatment (oral hygiene education with professional scaling) were reevaluated after 3 months. The levels of total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) were recorded. RESULTS GCF, salivary, and serum OSI were elevated in group T1DM compared to the other groups at baseline (p<0.05), and decreased in group T1DM at reevaluation compared to baseline (p<0.05). GCF OSI was positively correlated with periodontal clinical parameters (p<0.05). Glycated hemoglobin was positively correlated with GCF TOS (r=0.302, p=0.007), GCF OSI (r=0.346, p=0.002), salivary TOS (r=0.326, p=0.046), and serum TOS (r=0.239, p=0.044). CONCLUSION The instability in the oxidative status that accompanies diabetes may be considered a significant pathogenic factor of diabetes-related periodontal inflammation.

A Mutation in INSR in a Child Presenting with Severe Acanthosis Nigricans

Rabson-Mendenhall syndrome (RMS) is an autosomal recessive disorder due to mutations in the insulin receptor gene (INSR) which is mapped to 19p13.2. RMS is characterized by acanthosis nigricans, generalized lanugo, tooth and nail dysplasia, high nasal bridge, and growth retardation. A 5-year-old female patient was referred due to acanthosis nigricans and generalized lanugo. On her physical examination, severe acanthosis nigricans of the neck, axillae, the external genitalia and antecubital regions, generalized lanugo, mildly decreased subcutaneous fat, dysmorphic facial features, and polydactyly on her left hand were noted. Insulin resistance and impaired glucose tolerance were found. Sequence analysis of the INSR in the patient revealed c.3529+5G>A mutation in homozygous state. RMS should be suspected in a patient with characteristic physical features and insulin resistance.

Higher-Than-Conventional Subcutaneous Regular Insulin Doses in Diabetic Ketoacidosis in Children and Adolescents

Objective: To evaluate the effect of initial insulin dosage on glycemic control in the first 48 hours of subcutaneous regular insulin therapy after resolution of diabetic ketoacidosis (DKA). Methods: Records of patients with DKA hospitalized in the past 3 years [n=76, median age=10.0 (6.0-12.0) years, Male/Female: 44/32] were reviewed. The patients were designated into two groups according to distribution of starting doses of subcutaneous insulin. Group 1 (n=28) received a median dose of 1.45 U/kg/day (1.41-1.5) and group 2 (n=48) a median dose of 0.96 U/kg/day (0.89-1). Clinical and laboratory data were analyzed. Results: Median, minimum, and maximum blood glucose levels of Group 1 in the first 48 hours of treatment were significantly lower than that of Group 2 [213 (171-242) vs. 255 (222-316), p=<0.001; 102 (85-151) vs. 129 (105-199), p=0.004; and 335 (290-365) vs. 375 (341-438), p=0.001, respectively]. The number of patients who experienced hypoglycemia (<70 mg/dL) were similar [Group 1, 5 (17.9%) vs. Group 2, 4 (8.3%), p=0.276] and none had severe hypoglycemia. In Group 1, the ratio of blood glucose levels within the target range (100-200 mg/dL) were higher (37.5% vs. 12.5%) and the number of results >200 mg/dL were lower (50% vs. 81.3%) compared to Group 2 (p=0.001 and p<0.001, respectively). Conclusion: After resolution of DKA, a higher initial dose of 1.4-1.5 U/kg/day regular insulin is associated with better glycemic control in children and adolescents without an increase in risk of hypoglycemia.