Avoiding diagnostic delay for mucopolysaccharidosis IIIB: do not overlook common clues such as wheezing and otitis...

Mucopolysaccharidosis IIIB (MPS IIIB) is an autosomal recessive lysosomal storage disorder. In comparison to Hurler syndrome (MPS I) and Hunter syndrome (MPS II), characteristic facial and physical features tend to be milder and progression of neurological symptoms may initially be slower. Obvious neurological and behavioural symptoms may not appear until age 2-6 years, but once they begin, progression is relentless, leading to death by the early 20s. Although there is currently no known cure for MPS IIIB, enzyme replacement clinical trials are showing hope for delay in the progression of symptoms. Early diagnosis is therefore necessary before neurological symptoms have progressed. In our case, MPS IIIB was diagnosed at an early age because recurrent wheezing and otitis media in conjunction with hepatomegaly were recognised as more than trivial findings. A thorough examination and a definitive proactive decision to perform a liver biopsy resulted in early diagnosis of a rare disease.