Known and novel splice variants of CLRN1. (1) NM_174878, the main CLRN1 variant comprises exons 0, 2, and 3. The 5′ UTR and 3′ UTRs are not counted in the exon nucleotide number (in brackets). Known human CLRN1 splice variants or EST sequences from gene databanks: (4) NM_052995, the original CLRN1 variant with exons 1, 2, 3a, and 3b reported in 2001; (5) AF388368, coding region only 30-aa long; (6) BM666773 found from retina, exons 1 and 2 are coded in an alternative reading frame compared with the other splice variants, and a stop codon appears in this frame in exon 2 (presence of a stop codon marked with a red star); (10) BX491536, exon 0 open reading frame (ORF) continues to the intron until stop codon, potentially codes for 87-aa protein; and (11) CV570593, exon 2 continues to the intron, codes for a potentially 167-aa long protein. Novel splice variants found in human retina cDNA library (marked with an asterisk): (2) HM626132, main variant with added exon 2b; (3) HM626133, main variant with added exons 0b and 2b; and (7–9) HM626134, HM626135 and HM626136, splice variants between exons 0 and 1b. CLRN1 exon 2 is also connected by splicing to three EST sequences downstream of CLRN1. Downstream EST sequences from databanks are (15) BE673203, (16) DV080481, and (17) DV080691. The 5′ UTR is unknown, but presumed in this figure to start from exon 2. Possible ORFs in these variants (12–14: HM626137, HM626138, and HM626139) are depicted as arrows. ORFs that continue the same ORF as in CLRN1 exon 2 are depicted as green arrows, reading frames in blue and red begin from exon 2, but are not in the same ORF as CLRN1. Two ORFs running in opposite direction than CLRN1 ORF are depicted as orange in either solid or dashed line. The exon and intron sizes are not drawn in scale.