Publications (32) View all
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Article: Biomarkers in primary open angle glaucoma.
Haris Kokotas, Christos Kroupis, Dimitrios Chiras, Maria Grigoriadou, Klea Lamnissou, Michael B Petersen, George Kitsos[show abstract] [hide abstract]
ABSTRACT: Abstract Glaucoma, a leading cause of blindness worldwide, is currently defined as a disturbance of the structural or functional integrity of the optic nerve that causes characteristic atrophic changes in the optic nerve, which may lead to specific visual field defects over time. This disturbance usually can be arrested or diminished by adequate lowering of intraocular pressure (IOP). Glaucoma can be divided roughly into two main categories, 'open angle' and 'closed angle' glaucoma. Open angle, chronic glaucoma tends to progress at a slower rate and patients may not notice loss of vision until the disease has progressed significantly. Primary open angle glaucoma (POAG) is described distinctly as a multifactorial optic neuropathy that is chronic and progressive with a characteristic acquired loss of optic nerve fibers. Such loss develops in the presence of open anterior chamber angles, characteristic visual field abnormalities, and IOP that is too high for the healthy eye. It manifests by cupping and atrophy of the optic disc, in the absence of other known causes of glaucomatous disease. Several biological markers have been implicated with the disease. The purpose of this study was to summarize the current knowledge regarding the non-genetic molecular markers which have been predicted to have an association with POAG but have not yet been validated.Clinical Chemistry and Laboratory Medicine 01/2012; · 2.15 Impact Factor -
Article: Clinical and molecular aspects of aniridia.
H Kokotas, M B Petersen[show abstract] [hide abstract]
ABSTRACT: Aniridia is a severe, congenital ocular malformation inherited in an autosomal-dominant fashion with high penetrance and variable expression. Eye morphogenesis in humans involves a molecular genetic cascade in which a number of developmental genes interact in a highly organized process during the embryonic period to produce functional ocular structures. Among these genes, paired box gene 6 (PAX6) has an essential role as it encodes a phylogenetically conserved transcription factor almost universally employed for eye formation in animals with bilateral symmetry, despite widely different embryological origins. To direct eye development, PAX6 regulates the tissue-specific expression of diverse molecules, hormones, and structural proteins. In humans, PAX6 is located in chromosome 11p13, and its mutations lead to a variety of hereditary ocular malformations of the anterior and posterior segment, among which aniridia and most probably foveal hypoplasia are the major signs. Aniridia occurs due to decreased dosage of the PAX6 gene and exists in both sporadic and familial forms. The mutations are scattered throughout the gene and the vast majority of those reported so far are nonsense mutations, frameshift mutations, or splicing errors that are predicted to cause pre-mature truncation of the PAX6 protein, causing haploinsufficiency. Here we review the data regarding the mechanisms and the mutations that relate to aniridia.Clinical Genetics 05/2010; 77(5):409-20. · 3.13 Impact Factor -
Article: The novel c.247_249delTTC (p.F83del) GJB2 mutation in a family with prelingual sensorineural deafness.
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ABSTRACT: Non-syndromic hearing loss is one of the most common hereditary determined diseases in human, and the disease is a genetically heterogeneous disorder. Mutations in the GJB2 gene, encoding connexin 26 (Cx26), are a major cause of non-syndromic recessive hearing impairment in many countries and are largely dependent on ethnic groups. Due to the high frequency of the c.35delG GJB2 mutation in the Greek population, we have previously suggested that Greek patients with sensorineural, non-syndromic deafness should be tested for the c.35delG mutation and the coding region of the GJB2 gene should be sequenced in c.35delG heterozygotes. Here we present on the clinical and molecular genetic evaluation of a family suffering from prelingual, sensorineural, non-syndromic deafness. A novel c.247_249delTTC (p.F83del) GJB2 mutation was detected in compound heterozygosity with the c.35delG GJB2 mutation in the proband and was later confirmed in the father, while the mother was homozygous for the c.35delG GJB2 mutation. We conclude that compound heterozygosity of the novel c.247_249delTTC (p.F83del) and the c.35delG mutations in the GJB2 gene was the cause of deafness in the proband and his father.International journal of pediatric otorhinolaryngology 04/2012; 76(7):969-71. · 0.85 Impact Factor -
Article: Complex distal 10q rearrangement in a girl with mild intellectual disability: follow up of the patient and review of the literature of non-acrocentric satellited chromosomes.
Catherine Sarri, Sofia Douzgou, Yolanda Gyftodimou, Zeynep Tümer, Kirstine Ravn, Angela Pasparaki, Theologia Sarafidou, Harry Kontos, Haris Kokotas, Georgia Karadima, Maria Grigoriadou, Effie Pandelia, Virginia Theodorou, Nicholas K Moschonas, Michael B Petersen[show abstract] [hide abstract]
ABSTRACT: We report on an intellectually disabled girl with a de novo satellited chromosome 10 (10qs) and performed a review of the literature of the non-acrocentric satellited chromosomes (NASC). Satellites and stalks normally occur on the short arms of acrocentric chromosomes; however, the literature cites several reports of satellited non-acrocentric chromosomes, which presumably result from a translocation with an acrocentric chromosome. This is, to our knowledge, the third report of a 10qs chromosome. The phenotype observed in the proband prompted a search for a structural rearrangement of chromosome 10q. By microsatellite analysis we observed a 4 Mb deletion on the long arm of chromosome 10, approximately 145 kb from the telomere. FISH and array CGH analyses revealed a complex rearrangement involving in range from the centromere to the telomere: A 9.64 Mb 10q26.11-q26.2 duplication, a 1.3 Mb region with no copy number change, followed by a 5.62 Mb 10q26.2-q26.3 deletion and a translocation of satellite material. The homology between the repeat sequences at 10q subtelomere region and the sequences on the acrocentric short arms may explain the origin of the rearrangement and it is likely that the submicroscopic microdeletion and microduplication are responsible for the abnormal phenotype in our patient. The patient presented here, with a 15-year follow-up, manifests a distinct phenotype different from the 10q26 pure distal monosomy and trisomy syndromes.American Journal of Medical Genetics Part A 09/2011; 155A(11):2841-54. · 2.39 Impact Factor -
Article: High frequency of the TARDBP p.Ala382Thr mutation in Sardinian patients with amyotrophic lateral sclerosis.
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ABSTRACT: Recently, rare mutations in the TARDBP gene have been identified in familial and sporadic amyotrophic lateral sclerosis (ALS) patients. The purpose of this study was to characterize the genetic variability of the TARDBP gene in a cohort of Sardinian ALS patients. The coding region of the gene was analyzed in 97 unrelated patients previously tested negative for superoxide dismutase (SOD1) mutations. The p.Ala382Thr (c.1144G>A) mutation was found in 30 patients (30.9%). The mutation was predominant in familial ALS patients (FALS) as it was represented in 24 of 30 FALS cases (80%) (p < 0.0003). Six cases were apparently sporadic (9% of sporadic ALS patients). No further mutation of TARDBP was found in our cohort of ALS patients. Patients carrying the mutation showed spinal site of onset in 24 cases (80%), an average age at onset of 54.7 ± 11.1 years, not significantly different from patients not harboring TARDBP mutations (56.7 ± 9.6) and a female:male gender ratio of 1:1.1. The haplotype analysis carried out using eight microsatellite markers flanking the gene showed a founder effect for this mutation. Finally, we estimated the age-specific penetrance of the TARDBP p.Ala382Thr mutation in an additional sample of 47 carriers (20 affected and 27 unaffected). The average penetrance to 70 years was 60% (95% confidence interval 41-79%). A trend toward a higher penetrance in males was observed. Even in the presence of a causal mutation, most of the ALS clinical heterogeneity, however, draws upon from a multifactorial context.Clinical Genetics 03/2011; 81(2):172-8. · 3.13 Impact Factor