Sclerosteosis is an uncommon, autosomal recessive, progressive, sclerosing, bone dysplasia characterized by generalized osteosclerosis and hyperostosis of the skeleton, affecting mainly the skull and mandible. In most patients this causes facial paralysis and hearing loss. Other features are gigantism and hand abnormalities. In the present study, linkage analysis in two consanguineous families with sclerosteosis resulted in the assignment of the sclerosteosis gene to chromosome 17q12-q21. This region was analyzed because of the recent assignment to this chromosomal region of the gene causing van Buchem disease, a rare autosomal recessive condition with a hyperostosis similar to sclerosteosis. Because of the clinical similarities between sclerosteosis and van Buchem disease, it has previously been suggested that both conditions might be caused by mutations in the same gene. Our study now provides genetic evidence for this hypothesis.

We describe 3 patients with a new malformation syndrome in 2 sibships in a large kindred from Bahia, Brazil. The parents in both sibships are consanguineous. The syndrome is characterized by malformations of the face, ears, hands and feet, plus mixed deafness and pseudopapilledema. Fifty-four relatives were examined clinically and scored by the number of anomalies. A control sample of 54 individuals was equally examined. The distribution of the number of anomalies per individual (score) is bimodal in the relatives of the patients but unimodal in the control individuals. Detection of heterozygotes was based on the score distribution.

The effect of Black admixture is studied on the characteristics of Beckman’s scoring method. There is a significant cline on the mean scoring value for the interdigital area IV as the proportion of Negro ancestries increases (p < 0.05).