Genotypic and phenotypic correlations of biotinidase deficiency in the Chinese population
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(2019) 14:6
LETTER TO THE EDITOR
Open Access
Genotypic and phenotypic correlations of biotinidase deficiency in the Chinese population Rai-Hseng Hsu1,2,3, Yin-Hsiu Chien1,2, Wuh-Liang Hwu1,2, I-Fan Chang2, Hui-Chen Ho4, Shi-Ping Chou2, Tzu-Ming Huang1 and Ni-Chung Lee1,2*
Abstract Biotinidase deficiency is an autosomal recessive disorder that affects the endogenous recycling and release of biotin from dietary protein. This disease was thought to be rare in East Asia. In this report, we delineate the phenotype of biotinidase deficiency in our cohort. The genotypes and phenotypes of patients diagnosed with biotinidase deficiency from a medical center were reviewed. The clinical manifestations, laboratory findings, and molecular test results were retrospectively analyzed. A total of 6 patients were evaluated. Three patients (50%) were diagnosed because of a clinical illness, and the other three (50%) were identified by newborn screening. In all patients, the molecular results confirmed the BTD mutation. The three patients with clinical manifestations had an onset of seizure at the age of 2 to 3 months. Two patients had respiratory problems (one with apnea under bilevel positive airway pressure (BiPAP) therapy at night, and the other with laryngomalacia). Hearing loss and eye problems were found in one patient. Interestingly, cutaneous manifestations including skin eczema, alopecia, and recurrent fungal infection were less commonly seen compared to cases in the literature. None of the patients identified by the newborn screening program developed symptoms. Our findings highlight differences in the genotype and phenotype compared with those in Western countries. Patients with biotinidase deficiency benefit from newborn screening programs for early detection and management. Keywords: Biotinidase deficiency, Chinese population, Newborn screening program
Introduction Biotinidase deficiency (MIM #253260; BTD) is an autosomal recessive disorder affecting the endogenous recycling and release of biotin from dietary protein [1]. BTD results in low activities of biotin-dependent carboxylases and urinary excretion of organic acids characteristic of multiple carboxylase deficiency (MCD). BTD was first known as late-onset MCD because most patients present first symptoms after a month of age [2], and in 1982, Wolf et al. found that biotinidase is the primary enzymatic defect in late-onset MCD [3]. Patients with BTD can be divided into profound (residual activity < 10%) and partial deficiency (10–30%) due to the biphasic distribution of residual * Correspondence: [email protected] 1 Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei 10041, Taiwan 2 Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei 10041, Taiwan Full list of author information is available at the end of the article
enzyme activity [4]. Patients with profound BTD manifest with cutaneous symptoms including dermatitis, conjunctiviti
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