There is vitamin B6 – unresponsive and vitamin B6 – responsive cystathioninuria. The vitamin B6 – unresponsive form is thought to be from a lack of the synthesis of cystathionase. This means that the mutation in CTH from this form of cystathioninuria, results in the absence of cystathionase.
There are vitamin B6 – unresponsive and vitamin B6 – responsive cystathioninuria. The vitamin B6 – unresponsive form is believed to be caused by a deficiency in the production of cystathionase. This implies that the mutation in CTH from this type of cystathioninuria leads to the absence of cystathionase.