monocarboxylate transporter 8 deficiency (MCT8 deficiency)

Genetics

• X-linked
• associated with defects in SLC16A2

Clinical manifestations

• severe form of psychomotor retardation combined with hypothyroidism
• hypothyroidism can be caused by defects of hormone synthesis & action, but it has also been linked to a defect in cellular hormone transport
• affected patients are males
• severe neurological abnormalities, including
  • global developmental delay,
  • central hypotonia
  • spastic quadriplegia
  • dystonic movements
  • rotary nystagmus
  • impaired gaze & hearing
• heterozygous females had a milder thyroid phenotype & no neurological defects

Laboratory

• thyroid function tests
  • abnormal relative concentrations of 3 circulating iodothyronines

More general terms

• enzyme deficiency
• X-linked disease

Database

• OMIM: https://mirror.omim.org/entry/300523