Edward Syndrome (Trisomy 18)
The constellation of prominent occiput, overlapping fingers, rocker-bottom feet, and cardiac malformation is pathognomonic for Edward syndrome (Trisomy 18), making this the most likely diagnosis. 1
Clinical Reasoning
The clinical presentation described represents the classic phenotype of Trisomy 18:
Clenched fists with overlapping fingers are a characteristic and highly specific feature of Trisomy 18, where the index finger overlaps the third finger and the fifth finger overlaps the fourth 1, 2, 3
Rocker-bottom feet (talipes deformity) are a common finding in Trisomy 18 1, 3
Prominent occiput is a typical craniofacial feature that helps distinguish Trisomy 18 from other chromosomal abnormalities 3
Cardiac malformations are among the most frequent major malformations in Trisomy 18, occurring in the majority of cases, with ventricular septal defects (77.4%), patent ductus arteriosus (59.5%), and atrial septal defects (45.2%) being most common 1, 4
Why Not the Other Options
Down syndrome (Trisomy 21) typically presents with hypotonia, upslanting palpebral fissures, flat facial profile, and single palmar creases—none of which match this presentation 2
Patau syndrome (Trisomy 13) characteristically shows midline defects including holoprosencephaly, cleft lip/palate, and polydactyly, which are not described here 2
Turner syndrome affects only females and presents with lymphedema, webbed neck, and coarctation of the aorta, but not the specific hand and foot findings described 2
Clinical Context and Prognosis
Trisomy 18 is the second most common autosomal trisomy after Down syndrome, with a live birth prevalence of 1/6,000-1/8,000 2, 5. The mortality rate is high, with approximately 75-95% of infants dying in the first year of life, primarily due to cardiac failure, respiratory insufficiency, central apnea, and aspiration 2, 5. However, approximately 50% survive beyond the first week and 5-10% beyond the first year 2.
Immediate Management Priorities
Comprehensive cardiac evaluation is essential given the high prevalence of life-threatening cardiac defects, as these are the primary determinants of early mortality 5, 4. Echocardiography should be performed urgently to define the specific cardiac anatomy 4.
Feeding assessment is critical, as feeding problems occur consistently and may require enteral nutrition 2, 5.
Airway evaluation should be performed, as upper airway obstruction is more common than previously recognized and contributes to mortality 2.