Outcomes of oral biotin treatment in patients with biotinidase deficiency - Twenty years follow-up

Edyta Szymańska; Małgorzata Średzińska; Agnieszka Ługowska; Magdalena Pajdowska; Dariusz Rokicki; Anna Tylki-Szymańska

doi:10.1016/j.ymgmr.2015.09.004

Outcomes of oral biotin treatment in patients with biotinidase deficiency - Twenty years follow-up

Mol Genet Metab Rep. 2015 Oct 6:5:33-35. doi: 10.1016/j.ymgmr.2015.09.004. eCollection 2015 Dec.

Authors

Edyta Szymańska¹, Małgorzata Średzińska¹, Agnieszka Ługowska², Magdalena Pajdowska³, Dariusz Rokicki¹, Anna Tylki-Szymańska¹

Affiliations

¹ Department of Pediatrics, Nutrition and Metabolic Disorders, The Children's Memorial Health Institute, Warsaw, Poland.
² Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland.
³ Department of Biochemistry, Radioimmunology and Experimental Medicine, The Children's Memorial Health Institute, Warsaw, Poland.

Abstract

Introduction: Biotinidase deficiency (BTD) is an inborn error of biotin metabolism inherited as an autosomal recessive trait. Due to the, biotinidase deficiency, biotin is not recycled. Individuals with BTD usually exhibit neurological and cutaneous abnormalities unless treated with biotin. Supplementation with biotin may either ameliorate or if early introduced even prevent symptoms when introduced presymptomatically.

Patients and methods: Since 1991, 22 Polish patients from 19 families have been diagnosed with BTD. In 16 children the diagnosis had been suspected on the basis of clinical signs: skin lesions, hyperventilation, seizures, spasticity, and laboratory investigation (elevated lactate and metabolites on urine organic acids profile). The defect was enzymatically (serum biotinidase activity measurement) and genetically (tested for mutations in the BTD gene) confirmed afterwards. All patients were treated with biotin. Urine organic acids analysis (GC/MS) for 3-hydroxizovaleric acid was used for patients' monitoring. Neurological, audiological and ophthalmological evaluation has been conducted once a year.

Results: In 5 symptomatic patients a progressive optic nerve atrophy had already been noted at the time of treatment initiation. In these patients sensorineural hearing loss has also been diagnosed despite biotin supplementation. Asymptomatic patients treated with biotin supplementation presented no signs or symptoms of BTD. Supplementation with biotin slows the progression of BTD in symptomatic patients, but does not reverse nerve atrophy. Nonetheless, introduction of the treatment with biotin during presymptomatic stage of the disease prevents the onset of symptoms including optic atrophy and hearing loss. Homozygosity for the p.Leu215Phe mutation in BTD gene seems to be frequent in patients from the North-Eastern region of Poland and is connected with the hearing loss.

Conclusion: Since the prognosis for individuals diagnosed with BTD is good, provided they are treated before symptoms occur, it is justified to add this metabolic disorder to the panel of conditions screened under the national newborn screening programme in Poland.

Keywords: Biotin; Biotinidase deficiency; Newborn screening.