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Correspondence to Dr Babak Emamalizadeh, Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz 51368, Iran; [email protected]
Introduction
Jalili syndrome is a rare genetic disease that takes its name from the scientist Jalili who first characterised it during a blind school survey conducted in Gaza. He found 29 members of a family affected by the co-occurrence of two main symptoms: amelogenesis imperfecta (AI) and cone-rod dystrophy (CRD). Subsequently Jalili syndrome has been reported in many countries in all five continents. Most reported cases are familial but sporadic cases have also been identified. Patients with Jalili syndrome suffer from vision problems such as nystagmus, photophobia, loss of vision, and simultaneously experience tooth decay. Patients suffer with the aforementioned symptoms in their youth.1 This syndrome has an autosomal-recessive pattern of inheritance, and several mutations have been identified in the CNNM4 gene. In this review we summarise the reported clinical symptoms and genetic changes associated with this rare syndrome. Two major clinical manifestations of the Jalili syndrome include cone-rod dystrophy (CRD) and amelogenesis imperfecta (AI), which are outlined below.
Cone-rod dystrophy
Abnormal phenotypes due to mutations in the genes coding ciliary proteins are known as ciliopathies and may affect multiple and different organs including the retina, central nervous system, olfactory epithelium, cardiovascular system, kidney, liver, skeletal system, gonads, and adipose tissues. CRDs are progressive disorders known as retinal ciliopathies. Photoreceptors are neurons that convert absorbed light into electric response in a process known as phototransduction in which the rod and cone photoreceptors play the main role. These photoreceptors have different structures and protein compositions resulting in different functions; cones detect the high-resolution colour in bright light while rod photoreceptors are responsible for high sensitivity in dim environments.2 In photoreceptor dystrophies, photoreceptors are involved in disease progression primarily and are categorised as cone-rod, rod-cone and mixed receptors dystrophies. In cone-rod dystrophies, cones are the main cells involved in disease progression, while in rod-cone dystrophies (like retinitis pigmentosa), the rod cells are involved primarily. Mixed photoreceptor dystrophies are rare and include more complex disorders such as Leber congenital amaurosis.3
Mutations in several genes have been reported to be related to CRD, including AIPL1, CRX, GUCA1A, GUCY2D, PITPNM3, PROM1, PRPH2, RIMS1, SEMA4A and UNC119