HERC2 and OCA2 genes polimorphisms in relation to the iris color variation of the Belarusian population

The human genetic phenotyping is one of the most intensely developing area of forensic genetics. Externally visible traits, including eye color, can be predicted by analyzing single nucleotide polymorphisms with a high predictive rate. We studied the polymorphisms rs12913832 and rs1800407 in the HERC2 and OCA2 genes, respectively, to evaluate its prognostic availability in relation to the iris pigmentation of the Belarusian population. For this, both eye images and DNA samples were collected from 314 individuals to analyze the key polymorphisms by the TaqMan assay. Our data confirmed a relevance of rs12913832:A>G and rs1800407:G>A in the prediction context. The highest values of the sensitivity (SE = 0.94) and the specificity (SP = 0.90) were obtained for rs12913832, demonstrating the high efficiency of this marker as a classifier of phenotypic groups. The presence of the ancestral dominant allele rs12913832-A causes a dark (brown) iris pigmentation, how- ever, the heterozygous state rs12913832:GA includes a range of mixed variants. The predictive value of rs1800407 for the genetic phenotyping is highly significant (SE = 0.98), but has a low specificity (SP = 0.14), thus rs1800407, not being an effective classifier, can be used as an auxiliary in the eye color predictive model. The analysis of a cumulative impact of the both poly- morphisms on the iris color variation shows their high prospects for the genetic phenotyping of the Belarusian population.

Quantitative Cluster Headache Analysis for Neurological Diagnosis Support Using Statistical Classification

Cluster headache (CH) belongs to the group III of The International Classification of Headaches. It is characterized by attacks of severe pain in the ocular/periocular area accompanied by cranial autonomic signs, including parasympathetic activation and sympathetic hypofunction on the symptomatic side. Iris pigmentation occurs in the neonatal period and depends on the sympathetic tone in each eye. We hypothesized that the presence of visible or subtle color iris changes in both eyes could be used as a quantitative biomarker for screening and early detection of CH. This work scrutinizes the scope of an automatic diagnosis-support system for early detection of CH, by using as indicator the error rate provided by a statistical classifier designed to identify the eye (left vs. right) from iris pixels in color images. Systematic tests were performed on a database with images of 11 subjects (four with CH, four with other ophthalmic diseases affecting the iris pigmentation, and three control subjects). Several aspects were addressed to design the classifier, including: (a) the most convenient color space for the statistical classifier; (b) whether the use of features associated to several color spaces is convenient; (c) the robustness of the classifier to iris spatial subregions; (d) the contribution of the pixels neighborhood. Our results showed that a reduced value for the error rate (lower than 0.25) can be used as CH marker, whereas structural regions of the iris image need to be taken into account. The iris color feature analysis using statistical classification is a potentially useful technique to investigate disorders affecting the autonomous nervous system in CH.

A Case of Bilateral Acute Depigmentation of the Iris in One of Two Identical Twins

Background: Bilateral Acute Depigmentation of the Iris (BADI) is a condition which was first described in a case series from Turkey by Tugal-Tutkin and Urgancioglu in 2006.1 The condition is characterized by bilateral acute depigmentation and discoloration of the iris stroma, pigment dispersion, and deposition of pigment in the angle. In our case we report one of two identical twin sisters who developed BADI after receiving sarapin injections for chronic migraine, while the other has normal iris architecture and pigmentation and never received any like invasive procedure. Case Presentation: Patient is a 41 year old female with history of Sarapin injections to her face for chronic migraine who later developed bilateral depigmentation of the iris. She did not have any signs of anterior segment uveitis or iridocyclitis. She has a twin sister who maintained normal iris pigmentation during the entire course. Discussions and Conclusion: Bilateral Acute depigmentation of the iris is a recently discovered condition described in the literature in Turkish patients1,2. This condition affects mainly young females and is characterized by acute bilateral stromal depigmentation without other pathologic ocular findings. These patients usually maintain normal vision and do not develop significant glaucoma from pigment collecting in the anterior chamber angle. This condition can be mistaken for Fuch’s heterochromic iridocyclitis, pigment dispersion syndrome, pseudoexfoliation syndrome, viral iridocyclitis, VZV, HSV, and CMV. This is the first reported case in North America and is important for differentiation of the above pathologies. Our patient had a history of Sarapin injections to the face but it is unsure if this is associated with our patient’s development of BADI. As awareness of this condition progresses a possible etiology may be elucidated. Keywords: Iris; depigmentation; Sarapin, iris transillumination.