Absence of the c.169+50delTAAACAG mutation of SOD1 gene in a sample of keratoconus patients in Brazilian population.

OBJECTIVE: To determine the presence of the 7-bp deletion c.169+50delTAAACAG in intron 2 of Superoxide Dismutase-1 gene in keratoconic patients from the State of São Paulo, Brazil, which promotes splicing variations, resulting in non-functional Superoxide Dismutase-1 antioxidant proteins, which may damage the corneal structure. RESULTS: A group of 35 keratoconic patients, from whom 35 peripheral blood samples and 58 samples of corneal fragments were evaluated, and a control group of 89 individuals, from whom 41 blood samples and 149 samples of corneal fragments were collected. After the amplification of DNA fragments by polymerase chain reaction, mutational screening analysis was performed by enzymatic digestion, followed by direct sequencing. The absence of the 7-bp c.169+50delTAAACAG mutation in intron 2 of Superoxide Dismutase-1 gene was detected in the analyzed subjects of the 2 groups, both in the cornea and peripheral blood samples. Then, according to our results, there is no involvement of c.169+50delTAAACAG deletion in the pathogenesis of keratoconus in this population, once it was not detected. But we emphasize that studies involving this deletion must be continued in an attempt to elucidate this issue.

CCR5 chemokine receptor gene polymorphisms in ocular toxoplasmosis.

CC chemokine receptor type 5 (CCR5) is a chemokine receptor that influences the immune response to infectious and parasitic diseases. This study aimed to determine whether the CCR5Δ32 and CCR5 59029 A/G polymorphisms are associated with the development of ocular toxoplasmosis in humans. Patients with positive serology for Toxoplasma gondii were analyzed and grouped as 'with ocular toxoplasmosis' (G1: n=160) or 'without ocular toxoplasmosis' (G2: n=160). A control group (G3) consisted of 160 individuals with negative serology. The characterization of the CCR5Δ32 and CCR5 59029 A/G polymorphisms was by PCR and by PCR-RFLP, respectively. The difference between the groups with respect to the mean age (G1: mean age: 47.3, SD±19.3, median: 46 [range: 18-95]; G2: mean age: 61.3, SD±13.7, median: 61 [range: 21-87]; G3: mean age: 38.8, SD±17.9, median: 34 [range: 18-80]) was statistically significant (G1 vs.G2: p-value <0.0001; t=7.21; DF=318; G1 vs.G3: p-value <0.0001; t=4.32; DF=318; G2 vs. G3: p-value <0.0001; t=9.62; DF=318). The Nagelkerke r2 value was 0.040. There were statistically significant differences for the CCR5/CCR5 (p-value=0.008; OR=0.261), AA (p-value=0.007; OR=2.974) and AG genotypes (p-value=0.018; OR=2.447) between G1 and G2. Individuals with the CCR5/CCR5 genotype and simultaneously the CCR5-59029 AA or AG genotypes have a greater risk of developing ocular toxoplasmosis (4% greater), which may be associated with a strong and persistent inflammatory response in ocular tissue.