Chondrodysplasia punctata: A boy with X‐linked recessive chondrodysplasia punctata due to an inherited X‐Y translocation with a current classification of these disorders

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Abstract
Chondrodysplasia punctata (CDP) is a heterogeneous group of rare bone dysplasias characterized by punctate calcification of cartilage. The punctate calcifications are nonspecific and have been seen in a wide variety of disorders including the Zellweger syndrome, warfarin, dilantin, alcohol and rubella embryopathies, vitamin‐K‐epoxide‐reductase deficiency, chromosome trisomies 18 and 21, the Smith‐Lemli‐Opitz syndrome, prenatal infectious chondritis, hypothyroidism, and other rare disorders. We report on a boy with short stature, developmental delay, nasal hypoplasia, telebrachydactyly, hypoplastic genitalia, CDP, ichthyosis, hypoplastic genitalia, and a 46‐X, +der(X),t(X;Y)(p22.31;q11.21), Y karyotype. Genomic DNA probe analysis was interpreted as showing that the translocation breakpoint was within the X‐linked Kallmann syndrome gene. We review a current classification of these disorders that includes 3 well‐defined single gene disorders. These include an autosomal recessive rhizomelic type with early lethality, an X‐linked dominant type with presumed male lethality, and an X‐linked recessive type that has only been described as part of a contiguous gene deletion syndrome.