Figure 2. Characterization of genomic deletion including exons 1 to 7 of the MERTK gene in autosomal recessive RP. A: Localization of allele-specific primers. Primer sequences and allele-specific PCR conditions are described in Materials and Methods and Results. B: PCR fragments amplified with allele-specific primers were separated with agarose gel electrophoresis. Wild-type (wt) allele (386 bp) amplified with Δ-F and Δ wt-R was detected in both affected individuals and in the unaffected control. The mutant (mt) allele (658 bp) amplified with Δ-F and Δ-mtR1 was seen only in RP115 and RP116 and not in the control due to the presence of a large genomic deletion. C: Sanger sequencing shows the junction of two sequences where GCA (in bold) exists on both ends of the deletion breakpoints. G in italics represents the retained nucleotide compared to the site of the deletion described in patients from the Faroe Islands with retinitis pigmentosa [11]. D: Identification of a mutant allele with fragment analysis. The upper panel shows the presence of wt and mt alleles in RP115. The lower panel shows only the wt allele in a control sample. Fragments migrated as 370 and 400 bp despite their actual size of 354 and 386 bp (Table 1).