Rickets is a common metabolic bone disease in infants. The predominant cause of rickets is vitamin

Aim The aim of this study is to investigate the effects of vitamin B12 deficiency on hearing in school‐aged children by pure‐tone audiometry. Methods Forty‐three vitamin B12‐deficient children and 37 age‐matched control subjects were enrolled in the study. Tympanometric evaluations and pure‐tone audiometry including high frequencies were performed on the subjects. The results were compared between the two groups. Results Both right and left ear pure‐tone hearing thresholds (PTHTs) at 0.25–4 kHz, and four‐frequency pure‐tone average values were significantly better in the control group compared with the patient group (P < 0.05). However, PTHTs at 8–16 kHz were not different between the two groups (P > 0.05). Vitamin B12 level also did not show any significant correlation with the PTHTs at 0.25–16 kHz (P > 0.05). Conclusion This study indicates that vitamin B12 deficiency may contribute to hearing impairment at low frequencies as a possible aetiological factor in children.

ÖZKonjenital hiperinsülinizm (KHİ), yenidoğan ve erken infantil dönemde yineleyici veya inatçı ağır hipogliseminin en sık nedenlerinden birisidir. Hastalığın görülme sıklığı toplumlar arasında farklılık göstermekle birlikte, genel populasyondaki sporadik oranlar yaklaşık 40000-50000 canlı doğumda birdir. Araplar, Ashkenazi Yahudileri ve Türkler gibi akraba evliliklerinin yaygın olduğu toplumlarda hastalığın ailesel formlarının görülme oranı 2500 canlı doğumda bire kadar yükselebilir. Etiyolojide sıklıkla pankreatik beta hücrelerinden insülin salınımında rol alan yolaklardaki genetik bozukluklar sorumlu tutulmaktadır. Ancak bugüne dek tanımlanabilen mutasyonların oranı hemen hemen %50 düzeyindedir. KHİ'de en yaygın rastlanan genetik defekt, K+ATP kanallarını oluşturan SUR1 ve Kir. 6,2'yi kodlayan, 11. kromozomda lokalize ABCC8 ve KCNJ11 gen mutasyonlarıdır. Bu makalede homozigot KCNJ11 gen mutasyonuna bağlı KHİ tanısı konulan bir yenidoğan olgusu, hastalığın inatçı ağır neonatal hipogliseminin ayırıcı tanısında önemini vurgulamak ve yüklü aile öyküsü varlığında ileri genetik çalışmaların gerekliliğine dikkat çekmek amacıyla sunulmuş-tur.Anahtar kelimeler: Konjenital hiperinsülinizm, KCNJ11 gen mutasyonu, olgu sunumu ABSTRACT Congenital hyperinsulinism (CHI) is one of the most common causes of recurrent or persistent severe hypoglycemia in the neonatal period and early infancy. Although the incidence may vary widely among different populations, the sporadic rates in the general population is approximately 1/40,000-50,000 live births. The incidence of the familial forms may be as high as 1/2,500 in certain communities like Arabs, Ashkenazi Jews and Turks, in which consanguineous marriages are common. Genetic disorders of the pathways of insulin release from pancreatic beta cells are frequently held responsible for the etiology. However the incidence rate of the identified mutations up to date is nearly 50 percent. The most common genetic defects found in CHI are mutations in the ABCCS and KCNJ11 genes, which are located on chromosome 11p and encode for the SUR1 and Kir 6.2 subunits of the KATP channels. Here we report a newborn infant diagnosed as CHI due to homozygous KCNJ11 gene mutation with the aim of emphasizing the importance of CHI in the differential diagnosis of persistent neonatal hypoglycemia and attracting attention to the necessity of further genetic studies in the presence of strong familial history.