A rare and unexpected case of Sanfilippo type IIIA was reported in a 13-month-old child following the observance of high levels of the enzyme creatinine kinase in the child’s blood.
The case report, “Mucopolysaccharidosis IIIA presenting with hyperckemia in a child,” was published in the journal Acta Neurologica Belgica.
Because patients with Sanfilippo syndrome type IIIA (also known as mucopolysaccharidosis, or MPS, type IIIA) do not display many obvious physical changes, the disease is often underdiagnosed.
The 13-month-old boy was referred to a pediatric neurology department to be evaluated for abnormally high blood levels of the enzyme creatine kinase, which is normally found in muscles and released into the blood as a result of muscle damage.
The parents reported normal early development, but the boy had restlessness and sleep disturbances at 9 months. Early symptoms that “alarmed his parents were behavioral problems such as restlessness, excessive crying in the night and frequent nocturnal wakening,” researchers wrote. “His parents also admitted to a delay in speech and communication although he was 13 months old.”
A physical examination of the child revealed overall normal features, except for mildly coarse facial features, enlargement of the liver, and curvature in the back. Laboratory tests also were normal except for high concentrations of blood creatinine kinase, a condition known as hyperCKemia.
At this stage, doctors suspected MPS, which was supported by imaging analyses with X-rays and magnetic resonance imaging (MRI).
Diagnosis was confirmed upon analysis for the enzyme sulphamidase, which is affected in patients with Sanfilippo type IIIA. The patient had no activity of this particular enzyme.
Researchers highlighted that this is the first report of an association between hyperCKemia and Sanfilippo type IIIA. This is particularly important as disease diagnosis is often delayed due to mild physical features and slow progression of neurological features.
“This case also shows that, it has to be kept in mind that nonspecific developmental delay may precede behavioral disturbances in childhood, without any other sign suggestive of MPS IIIA,” researchers concluded.