Advances in human genetics. 5 / edited by Harry Harris and Kurt Hirschhorn.

Date:
1975
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Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Advances in human genetics. 5 / edited by Harry Harris and Kurt Hirschhorn. Source: Wellcome Collection.

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    36 David L. Rimoin of the diastrophic variant are similar to those of diastrophic dwarfism, but less severe. We have studied rib and iliac crest cartilage from one patient with the diastrophic variant and found generalized cartilage degeneration identical to that seen in diastrophic dwarfism (Fig. 6C). The chondrocytes were larger than normal and there were focal degeneration of cartilage, cyst formation, and fibrovascular scarring. The growth plate, however, was not significantly affected; the columns of chondrocytes were of normal length and diameter. This last observation would account for the less severe growth retardation observed in the diastrophic variant. Thus similar pathogenetic mechanisms appear to be operative in dia¬ strophic dwarfism and the diastrophic variant, suggesting that these two dis¬ orders may well be allelic, resulting from different mutations within the same gene. Chondrodysplasia Punctata Chondrodysplasia punctata is a heterogeneous group of disorders associated with radiographic stippling of the epiphyses and extra epiphyseal cartilage.^'^^^'^®®'^°®'^°®'^^°'^22 These disorders have been referred to by a variety of names, including Conradi's disease, Chondrodystrophia calcificane congenita, epiphyseal dysplasia punctata, and stippled epiphyses. Spranger et д/.зоз.зоб.зю recently pointed out that chondro¬ dysplasia punctata is not a homogeneous disorder, and can be classified into two and perhaps more distinct genetic syndromes. Furthermore, stippling of the epiphyses may be found in a variety of other diseases, including the cerebrohepatorenal syndrome, multiple epiphyseal dysplasia, Gmi ganglio¬ sidosis, the Smith-Lemli-Opitz syndrome, trisomy 18, trisomy 21, anenceph- aly, cretinism, and peripheral resistance to thyroxine.®®'^^^'^^®'^^° Chondro¬ dysplasia punctata will be described here under the two major headings that Spranger et have delineated. It is quite likely, however, that further heterogeneity exists within this group of diseases, Rhizomelic Type of Chondrodysplasia Punctata The rhizomelic type of chondrodysplasia punctata is characterized by severe rhizomelic shortening of the extremities, joint contractures, a high prevalence of cataracts (over 75%), ichthyosiform erythroderma with alopecia.