Six-month-old girl with dysmorphic appearance referred for genetic evaluation. Child is a product of a fraternal twin pregnancy; born at 41 weeks gestational age. Mother, age 32, received no prenatal care. Paternal age, 41 years.
Large head, unusual facial features, and a disproportionate body noted at birth. Cranial ultrasonogram normal at birth. Motor milestones delayed for a 6-month-old infant.
Well-appearing, happy infant. Weight, 5.5 kg (fifth percentile); height, 60.5 cm (under the fifth percentile). Occipitofrontal circumference, 47.5 cm (1.5 cm greater than 98th percentile). Anterior fontanel large: extends halfway down forehead. Posterior fontanel open. Low nasal bridge with prominent forehead (frontal bossing). Long narrow trunk with short arms and legs. Redundant skin folds on limbs. Short fingers and "trident" hands. Mild lumbar curvature of spine.
Infant is unable to hold her head up when prone. Able to roll back-to-front. Unable to "tripod" or sit without support.
This patient presents with the clinical features seen in infants with achondroplasia (A, B). This genetic syndrome is the most common form of short-limb dwarfism.1,2 It is marked by a large cranium, characteristic facial features, and disproportionate short stature with shortening of the proximal limbs (rhizomelia).1,2-4
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