Hypermagnesemia with Dystonia Type 2: Case Report of a New SLC30A10 Variant

Manganese-induced neurological disorder (HMNDYT1) is a rare condition characterized by the accumulation of manganese in the brain, leading to neurological symptoms such as difficulties in walking. This disorder arises due to genetic mutations affecting manganese transport and metabolism. Presented is the case of a 5-year-9-month-old female from the south region, evaluated for walking difficulties. Born to non-consanguineous parents, her early developmental milestones were typical. However, her initial workup revealed polycythemia and hypermagnesemia, with significantly elevated manganese concentrations in whole blood (880 μg/L). Whole exome sequencing identified a novel missense homozygous variant (c. 137C>A p.(Ser46Tyr)) in the SLC30A10 gene, classified as a variant of uncertain significance (class 3) by the ACMG scheme. Furthermore, both parents were carriers of a heterozygous missense pathogenic variant (c. 1336G>C p.(Asp446His)) in the HMNDYT1 gene. MRI results confirmed manganese deposition in the basal ganglia and other brain regions. Management included biweekly phlebotomies for polycythemia and oral iron supplementation to reduce hypermagnesemia absorption. After two months, the patient was scheduled to be reviewed for CBC, LFT, RFT, MRI, and bone profile analysis.