Editing ABC transporter (section)

==== ABCA ====
The ABCA subfamily is composed of 12 full transporters split into two subgroups.  The first subgroup consists of seven genes that map to six different [[chromosome]]s.  These are [[ABCA1]], [[ABCA2]], [[ABCA3]], and [[ABCA4]], [[ABCA7]], [[ABCA12]], and [[ABCA13]]. The other subgroup consists of [[ABCA5]] and [[ABCA6]] and [[ABCA8]], [[ABCA9]] and [[ABCA10]]. A8-10.
All of subgroup 2 is organized into a head to tail cluster of chromosomes on [[chromosome 17 (human)|chromosome 17]]q24.  Genes in this second subgroup are distinguished from ABCA1-like genes by having 37-38 exons as opposed to the 50 exons in ABCA1.  
The ABCA1 subgroup is implicated in the development of genetic diseases.  In the recessive Tangier's disease, the [[ABCA1]] protein is mutated.  Also, the [[ABCA4]] maps to a region of chromosome 1p21 that contains the gene for Stargardt's disease.  This gene is found to be highly expressed in rod photoreceptors and is mutated in Stargardt's disease, recessive retinitis pigmentism, and the majority of recessive cone-rod dystrophy.<ref name="Dean_2001"/>