PKHD1L1 and retinal degeneration: FAM186A and PKHD1L1 genes were excluded from the candidate list as homozygous loss of function mutations have been observed in a large number of individuals in the ExAC control cohort.25 Furthermore, IRS1 was excluded from further analysis as IRS1 has been previously linked to type 2 diabetes without retinal degeneration phenotype.33 As a result, IFT81 is the best candidate gene with one nonsense (c.1213C>T, p.R405*) and one missense variant (c.1841T>C, p.L614P) identified in the proband (NM_001143779).