Co-occurrence of achondroplasia and Down syndrome: Genotype/phenotype association

Area of Science:

• Genetics
• Pediatrics
• Medical Case Reports

Background:

• Down syndrome (DS) is a genetic disorder caused by trisomy 21.
• Achondroplasia is a common form of dwarfism resulting from a mutation in the FGFR3 gene.
• The co-occurrence of DS and achondroplasia is exceptionally rare, with only a few cases documented.

Observation:

• A male infant presented with features suggestive of both Down syndrome and achondroplasia.
• Diagnostic evaluations included physical examination, radiography, cytogenetic studies, and mutation analysis.
• Physical examination revealed characteristic signs of achondroplasia, including disproportionate limb shortening and lumbar lordosis.

Findings:

• Cytogenetic analysis confirmed Down syndrome with a karyotype of 47,XY,+21.
• Radiographic findings were consistent with achondroplasia.
• FGFR3 gene screening identified a heterozygous G1138A mutation, the cause of achondroplasia.

Implications:

• The combined genetic disorders resulted in a phenotype exhibiting features of both Down syndrome and achondroplasia.
• This case highlights the potential for de novo occurrence of multiple genetic conditions.
• Understanding the phenotypic interaction is crucial for accurate diagnosis and management.