Abnormalities of acid–base balance and predisposition to metabolic acidosis in Metachromatic Leukodystrophy patients

• Kidney sulfatide accumulation in MLD could cause a tubular defect.
• MLD patients show a tendency to sub-clinical metabolic acidosis.
• Severe metabolic acidosis could develop in acute clinical conditions.
• Correction of acid–base imbalances might prevent severe consequences of acidosis.
• Acid–base balance monitoring is recommended in clinical management of MLD patients.

Metachromatic Leukodystrophy (MLD; MIM# 250100) is a rare inherited lysosomal storage disorder caused by the deficiency of Arylsulfatase A (ARSA). The enzymatic defect results in the accumulation of the ARSA substrate that is particularly relevant in myelin forming cells and leads to progressive dysmyelination and dysfunction of the central and peripheral nervous system. Sulfatide accumulation has also been reported in various visceral organs, although little is known about the potential clinical consequences of such accumulation. Different forms of MLD-associated gallbladder disease have been described, and there is one reported case of an MLD patient presenting with functional consequences of sulfatide accumulation in the kidney.Here we describe a wide cohort of MLD patients in whom a tendency to sub-clinical metabolic acidosis was observed. Furthermore in some of them we report episodes of metabolic acidosis of different grades of severity developed in acute clinical conditions of various origin. Importantly, we finally show how a careful acid–base balance monitoring and prompt correction of imbalances might prevent severe consequences of acidosis.