This case represents de novo origin of two disorders that both may be parental-age related

Birth Defects Res A Clin Mol Teratol. 2010 Apr;88(4):228-31.

Co-occurrence of achondroplasia and Down syndrome: Genotype/phenotype association.
de Azevedo Moreira LM, Matos MA, Schiper PP, Carvalho AF, Gomes IC, Rolemberg JC, Ferreira de Lima RL, Toralles MB.

Laboratory of Human Genetics and Mutagenesis, Biology Institute, Federal University of Bahia, Barão de Geremoabo, Salvador, Bahia, Brazil. lazevedo@ufba.br

Abstract
BACKGROUND: This report describes the sixth case of an unusual association: Down syndrome with achondroplasia. It also analyzes the effects of both of these disorders on patient phenotype. METHODS: A male infant was evaluated for Down syndrome. His appearance also suggested a diagnosis of achondroplasia. The child was evaluated by physical examination, radiography, cytogenetic study, and mutation analysis. RESULTS: Chromosome analysis showed a karyotype of 47,XY,+21 in all 30 cells analyzed. Radiographic examination showed typical findings of achondroplasia, such as disproportionately large skull, shortening of limb segments, and lumbar lordosis. FGFR3 screening showed a heterozygous G1138A mutation. CONCLUSIONS: The interaction of these two distinct genetic disorders in the same patient produces a phenotype typical of each syndrome with some overlapping signs. This case represents de novo origin of two disorders that both may be parental-age related. (c) 2010 Wiley-Liss, Inc.