Biotinidase deficiency should be considered in individuals exhibiting myelopathy with or without and vision loss.

Multiple symptomatic children with biotinidase deficiency have exhibited spastic para- or tetraplegia due to myelopathy with and without vision loss. Although this has been a feature of what has been designated as delayed onset-biotinidase deficiency, myelopathy is likely also on the continuum of clinical features seen in younger children who have had these features attributed to dysfunction of the upper brain rather than of the spinal cord. Because many countries are still not screening their newborns for biotinidase deficiency, the disorder should be included in the differential diagnosis of individuals with myelopathic symptoms. Many of these children have gone weeks to months before they were correctly diagnosed with biotinidase deficiency. Rapid recognition that a child with myelopathy with and without vision loss has biotinidase deficiency will undoubtedly facilitate prompt treatment, increase the possibility of complete recovery and avoid potential residual permanent neurological damage. Newborn screening for biotinidase deficiency would avoid the delay in the diagnosis and treatment of individuals who otherwise may present with myelopathic or other neurological symptoms.

Detection of biotinidase gene mutations in Turkish patients ascertained by newborn and family screening.

UNLABELLED: The incidence of biotinidase deficiency in Turkey is currently one of the highest in the world. To expand upon the information about the biotinidase gene (BTD) variations in Turkish patients, we conducted a mutation screening in a large series (n = 210) of probands with biotinidase deficiency, using denaturing high-performance liquid chromatography and direct DNA sequencing. The putative effects of novel mutations were predicted by computational program. Twenty-six mutations, including six novels (p.C143F, p.T244I, c.1212-1222del11, c.1320delG, p.V457L, p.G480R) were identified. Nine of the patients were symptomatic at the initial clinical assessment with presentations of seizures, encephalopathy, and lactic acidemia. The most common mutation in this group of symptomatic patients was c.98-104 del7ins3. Among the screened patients, 72 have partial and 134 have profound biotinidase deficiency (BD) of which 106 are homozygous for BTD mutations. The common mutations (p.R157H, p.D444H, c.98-104del7ins3, p.T532M) cumulatively accounted for 72.3% of all the mutant alleles in the Turkish population. CONCLUSION: The identification of common mutations and hot spot regions of the BTD gene in Turkish patients is important for mutation screening in the Turkish population and helps to ascertain carriers, may have impact on genetic counseling and implementing prevention programs.

The discovery of niacin, biotin, and pantothenic acid.

The aim was to describe the discovery of niacin, biotin, and pantothenic acid. By the 1920s, it became apparent that 'water-soluble B' (vitamin B) is not a single substance. In particular, fresh yeast could prevent both beriberi and pellagra, but the 'antipolyneuritis factor' in yeast is thermolabile, while the antipellagra factor is heat stable, suggesting that there are at least two water-soluble vitamins. Various terms were proposed for these water-soluble factors, but vitamins B(1) and B(2) were most widely used to refer to the thermolabile and heat-stable factors, respectively. Although vitamin B(1) proved to be a single chemical substance (thiamin), vitamin B(2) was ultimately found to be a complex of several chemically unrelated heat-stable factors, including niacin, biotin, and pantothenic acid. Recognition that niacin is a vitamin in the early 20th century resulted from efforts to understand and treat a widespread human disease - pellagra. American epidemiologist and US Public Health Service officer Joseph Goldberger (1874-1929) had been instrumental to elucidating the nutritional basis for pellagra. Goldberger conducted a classic series of observational and experimental studies in humans, combined with an extensive series of experiments with an animal model of the condition (black tongue in dogs). In contrast, recognition that biotin and pantothenic acid are vitamins occurred somewhat later as a result of efforts to understand microbial growth factors. The metabolic roles in humans of these latter substances were ultimately elucidated by human experiments using particular toxins and by studies of rare inborn errors of metabolism. Symptomatic nutritional deficiencies of biotin and pantothenic acid were, and continue to be, rare.

The neurology of biotinidase deficiency.

Biotinidase deficiency is an autosomal recessively inherited metabolic disorder in which the enzyme, biotinidase, is defective and the vitamin, biotin, is not recycled. Individuals with biotinidase deficiency, if not treated with biotin, usually exhibit neurological and cutaneous abnormalities. Biotin treatment can ameliorate or prevent symptoms. Biotinidase deficiency meets the major criteria for inclusion in newborn screening programs. With the advent of universal newborn screening for the disorder, the "window-of-opportunity" to characterize the consequences of the untreated disease is essentially gone. To understand the neurology of biotinidase deficiency, we must depend on what is already known about symptomatic individuals with the disorder. Therefore, in this review, the neurological findings of symptomatic individuals with profound biotinidase deficiency have been compiled to catalog the characteristic features of the disorder and the consequences of biotin treatment on these findings. In addition, based on the available evidence, I have speculated on the cause of neurological problems associated with the disorder. Future studies in biotinidase-deficient animals should allow us to demonstrate more definitively if these speculations are correct.

Biotinidase deficiency in a newborn.

INTRODUCTION: Biotinidase deficiency is an inherited disorder of biotin metabolism that is untreated may present within the first few month of life. OBJECTIVE: We report the exceptional observation of a biotinidase deficiency in Morocco. The rarity of this pathology, its age of onset, its mode of revelation and the lack of treatment in Morocco make the particularity of this observation. OBSERVATION: A newborn child born from a 24-year-old mother, followed by an estimated pregnancy of 37 weeks of amenorrhea according to the Farr score (morphological maturation score used for the dating of the pregnancy term). The infant presented at 7 days of life with a cutaneous-mucous eruption with icithiosic dry erythroderma of interest to the trunk, the face, the scalp associated with alopecia and depilation of the eyebrow. The biotinoidase deficiency was confirmed by its low serum concentration at 49 nka / l. The newborn died at 20 days of life before starting the specific treatment. CONCLUSION: Biotinidase deficiency is a rare condition requiring early screening and rapid management. The delay in diagnosis and the unavailability of treatment in Morocco can have fatal consequences.

Biotinidase deficiency: novel mutations and their biochemical and clinical correlates.

Biotinidase deficiency is a defect in the recycling of the vitamin biotin. Biotin supplementation can markedly improve the neurological and cutaneous symptoms of affected children and prevent symptoms in children identified by newborn screening or treated since birth. We have determined thirteen novel mutations in children with the disorder. Two nonsense mutations, eight single missense mutations, three allelic double missense mutations, and two are polymorphisms were identified in the biotinidase gene (BTD). One of the missense mutations, c.734G>A (p. C245Y), is the first to be reported that alters the cysteine in the putative location crucial for ester formation and binding of the biotinyl-moiety in the active site of the enzyme. These mutations add to the growing list of mutations that are helping to delineate structure/function relationships of the enzyme.

Peculiar neuroimaging and electrophysiological findings in a patient with biotinidase deficiency.

We report a patient with biotinidase deficiency with peculiar findings on her MRI brain. Subcortical cysts combined with Dandy Walker cyst on the brain MRI have never been reported. There are many documented case reports of biotinidase deficiency and several of them have included findings on neuroimaging. Subcortical cysts have been documented in one patient with biotinidase deficiency previously and on autopsy in one other patient. Video EEG on the same patient showed evidence of symptomatic generalized epilepsy.

Profound biotinidase deficiency in a child with predominantly spinal cord disease.

Biotinidase deficiency is an autosomal recessively inherited disorder that manifests during childhood with various cutaneous and neurological symptoms particularly seizures, hypotonia, and developmental delay. Spinal cord disease has been reported rarely. We describe a 3-year-old boy with profound biotinidase deficiency who presented with progressive spastic paraparesis and ascending weakness in the absence of the usual characteristic neurological manifestations. Supplementation with biotin resulted in resolution of paraparesis with persistent mild spasticity in the lower limbs. DNA mutation analysis revealed that he was homozygous for a novel missense mutation (C>T1339;H447Y) in the BTD gene. This case indicates that biotinidase deficiency should be included in the differential diagnosis of subacute myelopathy and emphasizes the importance of a prompt diagnosis to prevent irreversible neurological damage.