[5][6][7][8] MCT8 actively transports a variety of iodo-thyronines including the thyroid hormones T3 and T4.

[6] A genetic disorder (discovered in 2003[6] and 2004[9]) is caused by mutation in the transporter of thyroid hormone, MCT8, also known as SLC16A2, is believed to be account for a significant fraction of the undiagnosed neurological disorders (usually resulting in hypotonic/floppy infants with delayed milestones).

A knockout zebrafish line was generated in 2014 using the zinc-finger nuclease (ZFN)-mediated targeted gene editing system.

[12] Similar to human patients, the zebrafish larvae exhibited neurological and behavioral deficiencies.

They demonstrated reduced locomotor activity, altered myelin-related genes and neuron-specific deficiencies in circuit formation.