Alagille Syndrome or Williams syndrome - a Potential Missed Diagnosis

Biliary hypoplasia in Williams syndrome

How similar presenting issues led to a slower diagnosis of Williams Syndrome...

Conjugated hyperbilirubinaemia and biliary hypoplasia are not known to be features of Williams syndrome.

In this case, the initial presenting features were those of prolonged jaundice, biliary hypoplasia, and pulmonary branch stenosis, leading to the incorrect diagnosis of Alagille syndrome. Our attention has since been brought to other cases of Williams syndrome and prolonged conjugated hyperbilirubinaemia, one of whom was also initially thought to have Alagille syndrome (Metcalfe K; personal communication, 2005). There is some overlap between the clinical features of Alagille syndrome and Williams syndrome.³ Both syndromes are associated with poor feeding, short stature, and developmental delay. Cardiac abnormalities occur in both syndromes, and although classically Williams syndrome is associated with supravalvar aortic stenosis, pulmonary branch stenosis is also common.^3,5 It has been suggested that Williams syndrome should be looked for in all cases of supravalvar aortic stenosis or pulmonary branch stenosis.⁶ Although some minor dysmorphic features are shared by both syndromes, for example, depressed nasal bridge, the facies are described as being quite different. However, we highlight the difficulty in detecting subtle features in a baby of 6 weeks of age. In our patient the facial characteristics were much more apparent at the age of 10 months.