Complete achromatopsia is a rare autosomal recessive disease associated with CNGA3, CNGB3, GNAT2 and PDE6C mutations. This retinal disorder is characterized by complete loss of color discrimination due to the absence or alteration of the cones function. The purpose of the present study was the clinical and the genetic characterization of achromatopsia in a large consanguineous Tunisian family. Ophthalmic evaluation included a full clinical examination, color vision testing and electroretinography. Linkage analysis using microsatellite markers flanking CNGA3, CNGB3, GNAT2 and PDE6C genes was performed. Mutations were screened by direct sequencing. A total of 12 individuals were diagnosed with congenital complete achromatopsia. They are members of six nuclear consanguineous families belonging to the same large consanguineous family. Linkage analysis revealed linkage to GNAT2. Mutational screening of GNAT2 revealed three intronic variations c.119À69G4C, c.161+66A4T and c.875À31G4C that co-segregated with a novel mutation p.R313X. An identical GNAT2 haplotype segregating with this mutation was identified, indicating a founder mutation. All patients were homozygous for the p.R313X mutation. This is the first report of the clinical and genetic investigation of complete achromatopsia in North Africa and the largest family with recessive achromatopsia involving GNAT2; thus, providing a unique opportunity for genotype-phenotype correlation for this extremely rare condition.

The aim of this study was to identify the genetic defect that is responsible for aniridia and congenital cataracts in two Tunisian families. Sequencing of the PAX6 gene in family F1 detected a novel c.265C4T transition in exon 6. In family F2, the previously described c.718C4T mutation in PAX6 was detected in the four affected members. This study adds new mutation to those previously reported in PAX6, providing further evidence for the genetic and phenotypic heterogeneity in individuals with aniridia ocular malformations.

SIGNIFICANCELipemia retinalis is a very rare ocular manifestation of severe hypertriglyceridemia. It is usually symptomatic and regresses after normalization of triglycerides levels. Early recognition is important to prevent ocular and life-threatening complications.PURPOSEThis study aimed to report a case of marked lipemia retinalis secondary to type V hypertriglyceridemia assessed with swept-source optical coherence tomography (OCT) and OCT angiography (OCT-A), with follow-up after dietary lipid restriction.METHODSObservational case report of lipemia retinal findings on color fundus photography, swept-source OCT and OCT-A, initially and after triglycerides lowering.CASE REPORTA 32-year-old pregnant patient with gestational diabetes and a history of hypertriglyceridemia was referred for diabetic retinopathy screening. Fundus examination revealed bilateral milky-white discoloration of retinal vessels with a “salmon-colored” retina. Swept-source OCT and OCT-A revealed extremely hyperreflective and dilated retinal vessels and multiple high-flow retinal hyperreflective dots, corresponding to dilated retinal capillaries. Choroidal vessels were enlarged and engorged, and choriocapillaris layer appeared thickened and hyperreflective with dilated and tortuous capillaries. Serum triglycerides were very high (70.02 mmol/L). After 21 days of very-low-fat diet, it was lowered to 15 mmol/L. We noted a normalization of the clinical, structural, and vascular findings. However, peripheral retinal vessels remained hyperreflective, despite their clinical normalization.CONCLUSIONSSwept-source OCT and OCT-A were beneficial in assessing lipemia retinalis noninvasively and monitoring choroidal and retinal vascular changes. Lipemia retinalis signs regressed initially in the posterior pole, choroidal anomalies were first to resolve, and clinical normalization preceded tomographic resolution.

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