DRD4
Subtypes
The
D4 receptor has the following variants D4.2, D4.3a, D4.3b, D4.4a, D4.4b,
D4.4c, D4.4d, D4.4e, D4.5a, D4.5b, D4.6a, D4.6b, D4.7a, D4.7b, D4.7c,
D4.7d, D4.8, D4.10. These variants differ in a variable number tandem
repeat domain present within the coding sequence of exon 3. Some of
these alleles are associated with greater incidence of certain diseases.
For example, the D4.7 alleles have an established association with attention-deficit
hyperactivity disorder.