CARTILAGE-HAIR HYPOPLASIA - A COMMON FORM OF DWARFISM IN FINLAND

Abstract

McKusick first described cartilage-hair hypoplasia (CHH) as a common type of dwarfism in the Old Order Amish. We have found a high frequency of CHH (at least 30 patients in a population of 4.6 million) in Finland. In order to characterize the clinical variability of this disorder, 13 males and 15 females from 1 to 23 years of age were studied (anthropometric measurements, skeletal x-rays, gastrointestinal malabsorption tests and a variety of immunologic tests). The measurements demonstrated the severe disproportion of the dwarfism, but also revealed the presence of vertebral involvement which had been previously overlooked. Even within this homogeneous group of patients, marked variability in the degree of dwarfism, body disproportion and hair diameter was found. Two cases of mild malabsorption were found in addition to one male who had been operated upon for congenital megacolon. Earlier studies have indicated severe and even fatal immunodeficiency against viral infections in CHH. All immunological studies in these patients were normal except for constantly low lymphocyte PHA stimulation indicating a defect in cell-mediated immunity. Tuberculin skin tests were negative in 61% of the patients in spite of prior BCG. This study demonstrates the high frequency of CHH in Finland and the marked variability in the expression of this autosomal recessive disorder.