Neuroimaging Features of Biotinidase Deficiency.

Biotinidase deficiency is an autosomal recessive condition caused by pathogenic variants in the BTD gene. Resultant deficiency of free biotin leads to impaired activity of the enzyme carboxylase and related neurologic, dermatologic, and ocular symptoms. Many of these are reversible on treatment, but early recognition and commencement of biotin supplementation are critical. This practice is especially important in countries where routine neonatal screening for biotinidase deficiency is not performed. In this report comprising 14 patients from multiple centers, we demonstrate the MR imaging patterns of this disorder at various age groups. Knowledge of these patterns in the appropriate clinical context will help guide early diagnosis of this treatable metabolic disorder.

Midface toddler excoriation syndrome (MiTES) can be caused by autosomal recessive biallelic mutations in a gene for congenital insensitivity to pain, PRDM12.

BACKGROUND: Midface toddler excoriation syndrome (MiTES) is a condition recently reported in three unrelated children. Habitual scratching from the first year of life inflicted deep, chronic, scarring wounds around the nose and eyes. One child had a mild neurological deficit but there was no other evidence of insensitivity to pain. Bilateral distribution and localization to the midface distinguish MiTES from other causes of self-inflicted skin damage such as trigeminal trophic syndrome. An earlier study of five siblings from a consanguineous Irish family, with lesions corresponding to MiTES plus other sensory deficits, showed homozygous mutations in a gene for hereditary sensory and autonomic neuropathy type VIII (HSAN8), PRDM12. OBJECTIVES: To study further cases of MiTES, including analysis of PRDM12. METHODS: We describe five further children, from four families, with facial lesions typical of MiTES, in whom mutation analysis of PRDM12 was carried out. RESULTS: Homozygous or compound heterozygous pathogenic expansions of the PRDM12 polyalanine tract were found in four of five affected individuals, in three families. CONCLUSIONS: Our finding of autosomal recessive mutations in PRDM12 in four of five patients with MiTES extends the phenotypic spectrum of PRDM12 mutations, which usually cause HSAN8, characterized by mutilating self-inflicted wounds of the extremities, lips and tongue. By contrast, MiTES shows severe midfacial lesions with little if any evidence of generalized pain insensitivity. The condition is probably genetically heterogeneous, and other congenital insensitivity to pain and HSAN genes such as SCN11A may be implicated. This new understanding of the nature of MiTES, which can masquerade as factitious disease, will facilitate appropriate management.

Mid-face toddler excoriation syndrome (MiTES): a new paediatric diagnosis.

Chronic ulcerating lesions on the face are rarely seen in toddlers. Blistering disease, vasculitis, infections and self-mutilation due to neurometabolic disease can usually be excluded on clinical and histological grounds. In the absence of identifiable disease, such lesions are sometimes attributed to child abuse or fabricated illness. We describe three toddlers with chronic mid-face erosions, two from India and one from the UK. One had moderate developmental delay and one had had seizures. The lesions appeared to be self-inflicted, no underlying disease was identified and there was no suspicion of child abuse. Recognition of the same disease pattern in different continents implies a distinct pathological entity. The pattern closely resembles that seen in some patients with mutations in the pain-insensitivity genes PRDM12 and SCN11A. We suggest the term 'mid-face toddler excoriation syndrome' (MiTES) to acknowledge the existence of this condition, encourage further reports and help clarify the pathogenesis.