Figure 2. ffERG panels for FAM1, FAM2, and FAM3. A: FAM1 unaffected full-field electroretinography (ffERG) cone and rod responses for patient #5908, heterozygous carrier of a mutation in USH2A. Non-detectable ffERG rod response and minimally reduced from normal cone response for patient #2334, compound heterozygous for two mutations in USH2A. B: Three members of FAM2 with reduced-to-minimal rod and cone ERG function. Patient #8438 was found to have two compound heterozygous mutations in USH2A, and patient #10228 had mutations in two autosomal dominant retinitis pigmentosa (adRP) genes, PRPH2 and PRPF8, as well as a single, heterozygous mutation in USH2A. Patient #10534 had a mutation in one adRP gene, PRPF8, as well as a single, heterozygous mutation in USH2A. C: Four members of FAM3 with varying degrees of ffERG dysfunction. Proband #5250 shows moderately reduced rod and cone responses and was found to harbor mutations in two autosomal dominant genes, PRPH2 and CRX. The proband’s son, #10396, had minor ffERG changes at age 8 years and was found to carry the mutation in CRX. Two additional family members, #6275 and #6121, carry only a single mutation in PRPH2 and show reduced-to-minimal ffERG responses.