Novel mutations including deletions of the entire OFD1 gene in 30 families with type 1 orofaciodigital syndrome: a study of the extensive clinical variability.

OFD1, now recognized as a ciliopathy, is characterized by malformations of the face, oral cavity and digits, and is transmitted as an X-linked condition with lethality in males. Mutations in OFD1 also cause X-linked Joubert syndrome (JBTS10) and Simpson-Golabi-Behmel syndrome type 2 (SGBS2). We have studied 55 sporadic and six familial cases of suspected OFD1. Comprehensive mutation analysis in OFD1 revealed mutations in 37 female patients from 30 families; 22 mutations have not been previously described including two heterozygous deletions spanning OFD1 and neighbouring genes. Analysis of clinical findings in patients with mutations revealed that oral features are the most reliable diagnostic criteria. A first, detailed evaluation of brain MRIs from seven patients with cognitive defects illustrated extensive variability with the complete brain phenotype consisting of complete agenesis of the corpus callosum, large single or multiple interhemispheric cysts, striking cortical infolding of gyri, ventriculomegaly, mild molar tooth malformation and moderate to severe cerebellar vermis hypoplasia. Although the OFD1 gene apparently escapes X-inactivation, skewed inactivation was observed in seven of 14 patients. The direction of skewing did not correlate with disease severity, reinforcing the hypothesis that additional factors contribute to the extensive intrafamilial variability.

New neurocutaneous syndrome with defect in cell trafficking and melanosome pathway: the future challenge.

OBJECTIVE: Case study of a CNS impairment lacking in presumptive cause; case presents with a clinical phenotype encompassing multiple differently expressed and combined symptoms, as well as a subtle skin defect. MATERIALS AND METHODS: A 6-year-old male with apparently isolated mental delay, speech delay, attention deficit/hyperactivity disorder, epilepsy, and subtle and insignificant skin dyschromias. The patient underwent a systematic evaluation, including clinical history; medical, neurological and ophthalmologic examinations. Skin, teeth, nails, hair and sudation were examined for defects. Routine laboratory tests for blood, urine, were performed. The proband had thyroid function tests, electrocardiography, genitourinary system and abdominal examinations. Special examinations pertaining to mental performance, biochemistry, chromosome studies, imaging and electrodiagnostic studies, and skin biopsy were also performed. RESULTS: Investigators ruled out genetic syndromes, congenital infections, fetal deprivation, perinatal insults, intrauterine exposure to drug abuse, and postnatal events such as CNS infections as possible common causes of brain impairment. Being all further test negative, the patient exhibited an ultrastructural defect of the skin, identical to that previously described [Buoni S, Zannolli R, de Santi MM, Macucci F, Hayek J, Orsi A et al. Neurocutaneous syndrome with mental delay, autism, blockage in intracellular vesicular trafficking and melanosome defects. Eur J Neurol 2006;13:842-51], suggesting that some cell compartments, such as rough endoplasmic reticulum, lysosomes, Golgi apparatus, and the vesicular zone (racket) of Birbeck granules, sharing similar components, can be altered, resulting in a common defect in cell trafficking, associated to melanosome defects. CONCLUSIONS: This new devasting, ultrastructural phenotype accompanied by apparently unspecific and mixed neurological symptoms should represent a future challenge to finally discover the pathogenesis of many childhood CNS symptoms, that currently seem to lack any apparent cause.