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.

Familial chilblain lupus, a monogenic form of cutaneous lupus erythematosus, maps to chromosome 3p

Systemic lupus erythematosus is a prototypic autoimmune disease. Apart from rare monogenic deficiencies of complement factors, where lupuslike disease may occur in association with other autoimmune diseases or high susceptibility to bacterial infections, its etiology is multifactorial in nature. Cutaneous findings are a hallmark of the disease and manifest either alone or in association with internal-organ disease. We describe a novel genodermatosis characterized by painful bluish-red inflammatory papular or nodular lesions in acral locations such as fingers, toes, nose, cheeks, and ears. The lesions sometimes appear plaquelike and tend to ulcerate. Manifestation usually begins in early childhood and is precipitated by cold and wet exposure. Apart from arthralgias, there is no evidence for internal-organ disease or an increased susceptibility to infection. Histological findings include a deep inflammatory infiltrate with perivascular distribution and granular deposits of immunoglobulins and complement along the basement membrane. Some affected individuals show antinuclear antibodies or immune complex formation, whereas cryoglobulins or cold agglutinins are absent. Thus, the findings are consistent with chilblain lupus, a rare form of cutaneous lupus erythematosus. Investigation of a large German kindred with 18 affected members suggests a highly penetrant trait with autosomal dominant inheritance. By single-nucleotide-polymorphism-based genomewide linkage analysis, the locus was mapped to chromosome 3p. Haplotype analysis defined the locus to a 13.8-cM interval with a LOD score of 5.04. This is the first description of a monogenic form of cutaneous lupus erythematosus. Identification of the gene responsible for familial chilblain lupus may shed light on the pathogenesis of common forms of connective-tissue disease such as systemic lupus erythematosus.