Gracile bones, periostal appositions, hypomineralization of the cranial vault, and mental retardation in brothers: milder variant of osteocraniostenosis or new syndrome?

We report on two brothers with ossification anomalies of membranous and cranial bones, remodeling defect of long bones leading to dense, overtubulated, narrow diaphyses, metaphyseal flare, periostal hyperosotosis that increased during the first months of life, thoracic dystrophy and severe hypotonia. One boy had hypospadias and cleft palate. Follow-up of the surviving boy documented progressive osteopenia, slow healing of the periostal anomalies, liver angiomatosis, mental and motor delay, thoracic deformity, delay in tooth eruption, and progressive microcephaly with enlargement of the cerebral ventricles. This disorder shares some traits with osteocraniostenosis, but lacks the cranial deformity and acromelic micromelia of the latter, in which periostal anomalies are not described. The syndrome reported here may represent a milder form of osteocraniostenosis, or a new entity belonging to the same "family." Genealogical data are consistent with AR or XLR inheritance. No mutations were found in the coding sequence of filamin A.