Glutaric aciduria type 1

Discussion:

Both brothers are affected by glutaric aciduria type 1. It is inherited in an autosomal recessive pattern, and their parents are first degree cousins. Although the findings described above are not by themselves specific, the combination of findings is highly suggestive of the diagnosis1. Macrocephaly is also a feature of this condition, and although it is difficult to appreciate macrocephaly on MRI, head circumference should be sought from the referring clinicians, as it significantly limits the differential2.

In the case of the older brother, imaging suggested the diagnosis before any metabolic investigations were carried out. Diagnosis was subsequently confirmed by urinary analysis and DNA sampling. His younger brother was screened at birth, allowing early post-natal diagnosis.

The changes in the lentiform nuclei are related to acute metabolic crises, and are a major cause of morbidity3. The more pronounced changes in the older brother reflect the longer duration of illness. Early treatment with a low protein diet may help slow neurological deterioration4, but in this family, treatment was hampered by language barrier and questionable compliance.

Importantly, glutaric aciduria type 1 can present with sub-dural hematomas as the increased extra-axial sub-arachoid spaces means the coursing bridging veins can easily rupture. This should not be mistaken for non-accidental injury.

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