Table 2.
Overlapping gene groups in human Chr 21 (Riken annotation)
| Gene locus | No. of exons, strand | Description | Relations |
|---|---|---|---|
| (1) GRIK1 | 17,− | Glutamate receptor | GRIK1 is linked to ALS; two Alus overlap the same internal exon of GRIK1; two claudin intronless genes, CLDN17 and CLDN8, are immediately 5′ to GRIK1 |
| (2) ORF41 | 2,+ | Spliced EST | |
| (3) ORF9 | 2,+ | Spliced EST | |
| (1) TIAM1 | 29,− | T-lymphoma invasion and metastasis-inducing TIAM1 protein | The Ψg (UBE3AP2) is immediately 3′ to TIAM1; the Ψg (BTRC2P) and then the disease gene SOD1 (causing ALS) is immediately 5′ to TIAM1 |
| (2) PRED31 | 3,+ | Predicted gene | |
| (1) ITSN | 12,+ | Intersectin-1 SH3 domain protein | An Alu sequence overlaps with the 3′ boundary exon of ITSN, which is overexpressed in the brain in Down's syndrome, suggesting a gene dosage contribution |
| (2) ATP50 | 7,− | ATP synthase OSCP subunit, oligomycin sensitivity conferring protein | |
| (1) DSCR1 | 4,− | Down's syndrome candidate region protein, proline-rich protein | DSCR1 may play a role in central nervous system development; the intronless gene KCNE1 (Lange-Nielsen syndrome) is immediately 3′ to DSCR1 |
| (2) PRED39 | 5,+ | Predicted gene | |
| (1) BACE2 (ASP2) | 9,+ | β-site APP-cleaving enzyme 2 | Decreased expression of ASP2 reduces amyloid β-peptide production, a precursor in amyloid plaque formation |
| (2) PRED43 | 4,− | Predicted gene | |
| (1) PKNOX1 | 11,+ | Homeobox-containing protein | CBS is associated with homocystinuria; an Alu overlaps an internal exon; the disease gene crystallin α-A and the progressive myoclonus epilepsy (EPM1) critical region of 21q22.3 are immediately 3′ to PKNOX1 |
| (2) CBS | 14,− | CBS | |
| (3) U2AF1 | 8,− | U2 snRNP auxiliary factor small subunit | |
| (1) HSF2BP | 9,− | Heat shock transcription factor 2 binding protein | The Ψg (RPL31P) and H2BFS are within the same boundary intron of HSF2BP; H2BFS is a single-exon gene |
| (2) H2BFS | 1,+ | H2B histone family S member | |
| (1) ORF30 | 2,+ | ORF | An Alu sequence overlaps with the 3′ exon of ORF30; the Ψg (IMMTP) is immediately 3′ to ORF30 |
| (2) ORF29 | 4,− | Spliced mRNA | |
| (3) ORF31 | 6,+ | Spliced EST | |
| (4) PRED53 | 7,− | Predicted gene | |
| (1) ADARB1 | 13,+ | dsRNA adenosine deaminase | An Alu sequence overlaps with an internal exon of ADARB1; at least four isoforms of ADARB1 have been identified |
| (2) PRED57 | 3,− | Predicted gene | |
| (3) PRED58 | 4,− | Predicted gene | |
| (1) PCBP3 | 11,+ | Poly (rC)-binding protein 3 | The disease gene COL6A1 (Bethlem myopathy) is immediately 3′ to PCBP3 |
| (2) PRED62 | 4,− | Putative gene containing transmembrane domain |
Ψg is the notation for pseudogene. There are four single-exon genes (CLDN17, CLDN8, KCNE1, and H2BFS) contained in, or proximal to, overlapping gene groups. There are eight recognized disease genes (GRIK1, SOD1, ITSN, DSCR1, KCNE1, CBS, CRYAA, and COL6A1) related to the overlapping gene groups.