CHST6 and macular corneal dystrophy: Patients with type I MCD usually harbour missense mutations and indels in the coding region of CHST6, which leads to the functional inactivation of the enzyme [12, 17], whereas deletions and/or rearrangements in the region between CHST6 and the neighbouring CHST5 have been reported in patients with MCD type II [1, 12].