Derya Kan

Lack of Association Between Matrix Metalloproteinase-9 and Endothelial Nitric Oxide Synthase Gene Polymorphisms and Coronary Artery Disease in Turkish Population

Polymorphic variants of genes encoding proteins involved in vascular remodeling may genetically diverge among different populations and play a role in the susceptibility to the coronary artery disease (CAD). MMP-9-1562 C/T (rs3918242), eNOS T-786C (rs2070744), and Glu298Asp (rs1799983) are among the most studied of these polymorphisms. The aim of this study was to determine the relationship between CAD and these polymorphisms in the Turkish population. The analysis included 146 CAD+ and 122 CAD- individuals. Genomic DNA was isolated from whole blood and genotyping was performed by the PCR-RFLP method. No significant associations were found between -1562 C/T (p = 0.557), Glu298Asp (p = 0.432), and -786 T/C (p = 0.055) polymorphisms and CAD. The distribution of each haplotype also did not differ between CAD+ and the CAD- samples (p > 0.05). The present investigation is the first to study an association between -1562 C/T polymorphism and CAD in the Turkish population. In conclusion, no appreciable differences between CAD+ and CAD- samples were found in terms of polymorphisms mentioned above.

An unexpected finding in a child with neurological problems: mosaic ring chromosome 18

Major neurological disorders may accompany rare chromosomal abnormalities. As an example of this rare condition, we present a case with microcephaly, mental retardation, developmental delay, hyperactivity, stereotypic movements, seizures and dysmorphic facial appearance in whom a mosaic ring chromosome 18 was found [45,XX,-18/46,XX,r(18)/46,XX,dicr(18)]. Although ring chromosome 18 phenotype has been known for a long time, this is the third reported patient with a dicentric ring chromosome 18 mosaicism. The presented case will contribute to the identification of the genotype-phenotype correlation in chromosome 18 anomalies.

The evaluation of long-term effects of ionizing radiation through measurement of current sister chromatid exchange (SCE) rates in radiology technologists, compared with previous SCE values

Ionizing radiation is a strong physical mutagen, causing breakage of phosphodiester bonds in DNA at any stage of the mitotic cycle. Analysis of sister chromatid exchange (SCE) has come into use as a sensitive DNA-damage indicator. We investigated the SCE rates in radiology technologists who are occupationally and chronically exposed to ionizing radiation. The study included 39 radiology technologists and 35 sex- and age-matched healthy controls. There was a statistically significant difference in the SCE frequency between radiology technologists and controls (p<0.0001). Additionally, previous SCE data of 10 radiology technologists were compared with current results regarding radiation exposure time. There was statistically significant difference between previous and current SCE values (p=0.005). The significant increase in the frequency of SCE in radiology technologists emphasizes the importance of radiation-protection procedures in order to minimize radiation exposure and avoid possible genotoxic effects. Comparison of two studies that measured SCE values of radiology technologists after 8 years also suggests that the genotoxic effect is reversible. In conclusion, radiation is still an important mutagenic agent despite improvements in daily working hours and conditions.

Two complementary recombinant chromosomes 5 in a healthy woman

We report a healthy woman with two abortions who is a carrier for a rare heterozygous double recombinant of an inv(5) chromosome, karyotype 46,XX,rec(5)dup(5p) inv(5)(p13q22),rec(5)dup(5q)inv(5)(p13q22). Her father had a 46,XY,inv(5)(p13q22) karyotype; his consanguineous wife had died. Molecular investigation of 11 highly polymorphic markers spanning chromosome 5 revealed biparental inheritance for two markers (D5S406, D5S681) on 5p15.3 and 5q13.1, and an allele constellation not compatible with paternal heterodisomy for marker D5S623 on 5q11.2. Eight markers were not informative. Three mechanisms of formation are proposed: First, fertilization of a normal oocyte by a sperm carrying the two recombinant chromosomes 5, followed by postzygotic recombination between the normal maternal homologue and the rec(5)dup(5p), and by loss of the mitotically recombined maternal homologue, leading to segmental paternal heterodisomy 5q13→qter (trisomic rescue). Second, postzygotic recombination in a 46,XX,inv(5)(p13q22) zygote resulting in the 46,XX,rec(5)dup(5p)inv(5)(p13q22),rec(5) dup(5q)inv(5)(p13q22) karyotype, followed by absence of the original cell line in lymphocytes. Third and most likely, both parents were inv(5) carriers and complementary recombinations in maternal and paternal meiosis resulted in a zygote with two recombinant chromosomes 5. Our patient refused any further studies but later reported the birth of a phenotypically normal child. This is the first report known to us of complementation by two non-homologous recombinant chromosomes in a phenotypically normal woman, and the first example of a child born to a carrier of complementary recombinant chromosomes.