Limb abnormalities on trisomy 18: evidence for early diagnosis.

OBJECTIVE

To assess the frequency and types of limb abnormalities observed among patients with trisomy 18, or Edwards syndrome (ES).

METHOD: The sample consisted of consecutive patients evaluated by a clinical genetics service in the period from 1975 to 2008. The results of the cytogenetic analysis, as well as the clinical data were retrieved from the medical records, with special attention to limb abnormalities findings. All the karyotype analysis was performed at the same laboratory.

RESULTS

During the study period, 50 patients were identified, 33 (66%) of them females, with ages at the first evaluation ranging from 1 day to 16 years (median 14 days). The single lineage with free trisomy 18 was the most frequent chromosomal disorder (90%). Mosaicism was observed in 10% of the cases. Clenched fist with overlapping fingers was the predominant anomaly of the upper limbs (70%). Other common disorders included the single palmar crease (42%) and hypoplastic nails (36%). Radial abnormalities were found in 11 patients (22%). As for the lower limbs, hypoplastic nails were the most common abnormality (58%), followed by the rocker bottom foot with prominent calcaneus (50%). One patient had unilateral ectrodactyly as well.

CONCLUSIONS

Despite the classical description, limb anomalies can be much variable in ES. Some patients may show unusual abnormalities, such as radial defects and ectrodactyly. These findings are extremely important for the clinical suspicion and early identification of patients with ES.