Familial transmission is now recognized in a small proportion of people with MacTel type 2; however, the nature of any related genetic defect or defects remains elusive. The MacTel genetic study team hopes that exome analysis in the affected population and relatives may be more successful in identifying related variants.

Although a variety of complex classification schemes are described in the literature, there are essentially two forms of macular telangiectasia: type 1 and type 2. Type 1 is typically unilateral and occurs almost exclusively in males after the age of 40.

Type 2 is mostly bilateral, occurs equally in males and females.