Clark-Baraitser syndrome: report of a new case and review of the literature.

We describe the case of a boy with moderate mental retardation associated with tall stature, obesity, macrocephaly and typical facial features, characterized by a large 'square' forehead, prominent supraorbital ridges, broad nasal tip, prominent lower lip and minor dental anomalies. We think that our proband is affected by Clark-Baraitser syndrome, a rare X-linked mental retardation disorder, to date described only in five male subjects. We present a more complete definition of the clinical phenotype of the syndrome with particular attention to the behavioural aspect that, in combination with the body size and the dysmorphic picture, we think is distinctive for the Clark-Baraitser syndrome. We also summarize the mild features described in female relatives of the patients, as it could disclose a possible carrier condition and be of help with genetic counselling in the families with male patients, until a molecular test is available.

Stickler syndrome caused by COL2A1 mutations: genotype-phenotype correlation in a series of 100 patients.

Stickler syndrome is an autosomal dominant connective tissue disorder caused by mutations in different collagen genes. The aim of our study was to define more precisely the phenotype and genotype of Stickler syndrome type 1 by investigating a large series of patients with a heterozygous mutation in COL2A1. In 188 probands with the clinical diagnosis of Stickler syndrome, the COL2A1 gene was analyzed by either a mutation scanning technique or bidirectional fluorescent DNA sequencing. The effect of splice site alterations was investigated by analyzing mRNA. Multiplex ligation-dependent amplification analysis was used for the detection of intragenic deletions. We identified 77 different COL2A1 mutations in 100 affected individuals. Analysis of the splice site mutations showed unusual RNA isoforms, most of which contained a premature stop codon. Vitreous anomalies and retinal detachments were found more frequently in patients with a COL2A1 mutation compared with the mutation-negative group (P<0.01). Overall, 20 of 23 sporadic patients with a COL2A1 mutation had either a cleft palate or retinal detachment with vitreous anomalies. The presence of vitreous anomalies, retinal tears or detachments, cleft palate and a positive family history were shown to be good indicators for a COL2A1 defect. In conclusion, we confirm that Stickler syndrome type 1 is predominantly caused by loss-of-function mutations in the COL2A1 gene as >90% of the mutations were predicted to result in nonsense-mediated decay. On the basis of binary regression analysis, we developed a scoring system that may be useful when evaluating patients with Stickler syndrome.