Prenatal diagnosis of nonrhizomelic chondrodysplasia punctata (Conradi-Hünermann syndrome).

Chondrodysplasia punctata has been classified into two major types including the rare autosomal recessive "rhizomelic type" and a more common but genetically heterogenous nonrhizomelic type (referred to by some authors as "Conradi-Hünermann (CH) type"). The former is typically lethal, manifesting serious anomalies, and allowing several instances of confident prenatal diagnosis. The latter being milder has more subtle anomalies and prenatal diagnosis has been uncommonly reported (confined to cases diagnosed incidentally by flat-plate X-ray examination of the mother in late third trimester, and a case found by directed ultrasound performed in a Mendelian affected mother). Cases included 1) a young primigravida thought to be affected with Conradi-Hünermann syndrome presented at 16 weeks gestation for prenatal diagnosis and counseling. Ultrasound examination of the fetus detected assymetric limb shortness allowing the presumptive diagnosis of an affected fetus which was confirmed after delivery near term. 2) A normal 38-year-old multipara with unremarkable family history underwent routine fetal ultrasound evaluation at 18 weeks gestation. Disorganization of the spine, premature echogenicity of femoral epipheses, and frontal bossing with depressed nasal bridge were described. Neonatal examination confirmed suspicion of CH. Case 1 demonstrates the importance of solid clinical diagnosis in Mendelian malformation-affected parents for directing prenatal diagnostic efforts. Case 2 represents the first index case of CH diagnosed antenatally by ultrasound. Diagnostic clues which must be considered in establishing these diagnoses are discussed, as are some of the difficulties and limitations in antenatal counseling such cases.