Pediatric TTLL5 -related retinopathy and a recurrent deletion in the United Arab Emirates

Purpose TTLL5‑related retinopathy, a rare form of autosomal recessive inherited retinal dystrophy, has been mostly documented in adults and as a cone-dominant disorder. This report highlights the phenotype in 2 affected children.Methods Retrospective case series of 2 affected siblings and their affected mother (pseudodominant nuclear family).Results Two Emirati sisters, 17 and 14 years old and from a first-cousin marriage, were evaluated for unexplained reduced vision despite grossly normal fundus exam since approximately 8 years of age and a suspicion for functional visual loss. Fundus examination was significant for areas of tapetal retinal sheen in both. Electroretinography revealed cone-rod dysfunction in the 17-year-old and cone dysfunction in the 14-year-old. Their mother, 61 years old, had bilateral macular atrophy and poor vision since childhood. Exome sequencing the older sister identified a homozygous TTLL5 deletion (encompassing exons 16–26) and segregation analysis confirmed it to be present in homozygosity in the younger sister and mother. This TTLL5 deletion is absent from major variant databases but has been previously reported in homozygosity in another Emirati patient with cone-rod dystrophy.Conclusions TTLL5-related retinopathy can be mistaken for functional visual loss or amblyopia in children, leading to delayed diagnosis. A tapetal retinal sheen seems recurrent. This rare homozygous TTLL5 deletion has been previously reported in a different Emirati patient with cone-rod dystrophy and may represent a founder effect in the population.