Apparent allelism of the hurler, scheie, and hurler/scheie syndromes

Abstract

The Hurler, Scheie, and Hurler/Scheie syndromes are clinically distinct disorders due to inherited deficiencies of lysosomal α‐iduronidase activity. The genetic relationship of these disorders was investigated by complementation analysis using a heterokaryon enrichment procedure. Fusions between fibroblasts derived from Hurler, Scheie, or Hurler/Scheie subjects in any combination resulted in no detectable correction of α‐iduronidase activity, indicating that they form a single complementation group. Control fusions between these fibroblasts and mucolipidosis II or III cells, which are also α‐iduronidase deficient due to an enzyme processing defect, resulted in restoration of up to 57% of normal α‐iduronidase activity. These results also suggest allelism of the Hurler, Scheie, and Hurler/Scheie syndromes. However, the genetic make‐up of the Hurler/Scheie syndrome was not resolved.