Co-occurrence of achondroplasia and Down syndrome: Genotype/phenotype association.
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.
de Azevedo Moreira
Lilia Maria
LM
Laboratory of Human Genetics and Mutagenesis, Biology Institute, Federal University of Bahia, Barão de Geremoabo, Salvador, Bahia, Brazil. lazevedo@ufba.br
Matos
Marcos A
MA
Schiper
Patricia P
PP
Carvalho
Acácia F L
AF
Gomes
Ivalda C
IC
Rolemberg
José C
JC
Ferreira de Lima
Renata L L
RL
Toralles
Maria B P
MB
D000130:Achondroplasia / Q000150:complications* / Q000235:genetics / Q000473:pathology; D019943:Amino Acid Substitution; D004314:Down Syndrome / Q000150:complications* / Q000235:genetics / Q000473:pathology / Q000523:psychology; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D008423:Maternal Age; D020125:Mutation, Missense; D010331:Paternal Age; D010641:Phenotype; D017354:Point Mutation; D051498:Receptor, Fibroblast Growth Factor, Type 3 / Q000235:genetics*
C496365:FGFR3 protein, human; D051498:Receptor, Fibroblast Growth Factor, Type 3