Achondroplasia-hypochondroplasia complex in a newborn infant

Area of Science:

• Genetics
• Pediatrics
• Skeletal Dysplasias

Background:

• Achondroplasia and hypochondroplasia are skeletal dysplasias caused by mutations in the fibroblast growth factor receptor 3 (FGFR3) gene.
• Genetic counseling and molecular testing are crucial for diagnosing skeletal dysplasias during pregnancy.
• This report focuses on a rare complex form of skeletal dysplasia.

Observation:

• Antenatal ultrasonography revealed severe fetal anomalies including short limbs, macrocephaly, and a small chest.
• The patient presented with rhizomelic limb shortening, large head, small chest, and mild lung hypoplasia postnatally.
• Clinical examination at 8 months showed disproportionate limb shortening, frontal bossing, depressed nasal bridge, and motor development delay.

Findings:

• Molecular testing confirmed compound heterozygous mutations in FGFR3: G1138A (achondroplasia) and C1620G (hypochondroplasia).
• Radiographs demonstrated characteristic features of achondroplasia, including shortened long bones and metaphyseal flaring.
• The patient exhibits features consistent with achondroplasia-hypochondroplasia complex, a condition with limited prior documentation.

Implications:

• This case highlights the importance of genetic testing for FGFR3 mutations in suspected skeletal dysplasias.
• Understanding the genetic basis of achondroplasia-hypochondroplasia complex can aid in prenatal diagnosis and management.
• Further research is needed to elucidate the long-term prognosis and management strategies for this rare condition.