Genetics in the Third Millennium
Volume:5 Issue: 4, 2008

Telomer consists of two parts telos and mers. telos means end and mer means part. The unique functional properties of chromosome ends were first noticed in the 1930s by the fly geneticist Herman Muller. Telomeres are capping structures at the ends of eukaryotic chromosomes, which consist of repetitive DNA bound to an array of specialized proteins. In most eukaryotes, telomeres are formed by tandem arrays of short G/C-rich repeats. The telomeric G-rich strand is always oriented with its 3’ end towards chromosome termini and forms short single-stranded protrusions called G-overhangs. The length of single-stranded protrusions range from 50 to 200 nucleotides and the current model predicts that G-overhangs are tucked into a duplex telomere forming so called t-loops. The function of telomeres is to prevent chromosome ends from being detected as damaged DNA. Both the length of telomere repeats and the integrity of the telomere-binding proteins are important for telomere protection. Telomere length is regulated by telomerase, by the telomere-binding proteins, as well as by activities that modify the state of the chromatin. This review discuss about function of the protection in the chromosome end in mammals, yeast, drosophila.

In 1978, Zamecnik and Stephenson explored that how nucleotides as antisense agents can inhibit viral replication process in vitro. Since that time antisense technology has been developed as a strong facility for therapeutic usages. Antisense molecules are complementary nucleic acids which specifically bind to the target mRNA and inhibits its translation. Theoretically, antisense molecules could be used to control over expressions of genes and related disorders like viral diseases, inflammations, cancers, etc. Despite of their simple structures, there are serious challenges for using of these materials which should be resolved in near future.

The true incidence of renal hereditary diseases and urinary tract anomalies is difficult to ascertain. The incidence is estimated to be 3-6 in 100000 live births. Infant deaths from genitourinary anomalies are estimated to be approximately 6.3% of all causes of infant mortality. The first step to approach to a child with urinary tract anomaly is to make a specific diagnosis based on history taking and physical examination. Chromosomal abnormalities are found in approximately 10-20% of all renal anomalies. The first and the best way to evaluation of kidney and urinary tract anomalies is ultrasonography. Other laboratory and imaging methods like as voiding cystourethrography, isotope scans, intravenous urography and biochemistry and genetic testes would be useful after ultrasonography. The genetic consult is necessary in every child with renal and urinary tract anomalies. The hereditary diseases of the kidney are renal anomalies, hereditary syndromes and associations and hereditary tubular and glomerular diseases which are going to be discussed in this article.

Neoplasias have a distinct pattern of disrupted pathways, which are the results not only of genetic alterations but also of heritable patterns of disrupted gene expression. Epigenetics refers to these changes in patterns of gene expression that are mediated by mechanisms that do not alter the primary DNA sequence. Epigenetic changes in tumors mostly result in inappropriate gene silencing. The transcriptionally silenced state is the consequence of alterations in chromatin sructure, including DNA hypermethylation and histone modifications. Therefore, epigenetic changes are the results of the two processes. A better understanding of the epigenetic mechanisms that cause transcriptional repression has allowed researchers to find new agents that open new possibilities for cancer therapies.

Ribosome-inactivating proteins (RIPs), mostly from plants, are enzymes which depurinate rRNA, thus inhibiting protein synthesis. These proteins also depurinate other polynucleotides. The biological activity of RIPs is not completely clarified, and sometimes independent of the inhibition of protein synthesis. Some RIPs are potent toxins, the best known being ricin induce production of cytokines causing inflammation. RIPs are potentially useful in agriculture and medicine because they have anti viral activity. The mechanism of action and role in nature of RIPs are not completely understood, and we can expect more advancement in their practical application. We will be more acquainted with the structure and function of these proteins in this review.

Pregnancy loss is a common problem in reproductive–aged women. Although most cases of pregnancy loss are sporadic, some couples experience recurrent pregnancy loss. A variety of possible etiologies have been described for recurrent pregnancy loss. In most cases, the cause is not apparent and often requires intensive and expensive clinical and laboratory investigations, despite which there is still a limited understanding of it. This review focuses on the genetic abnormalities that may contribute to this clinical problem and delineates strategies for genetic evaluation and clinical management in subsequent pregnancies.

Herein an Iranian family with two affected offspring with mental retardation and dysmorphic features is being reported. On detailed investigation they have been diagnosed that are suffering from Cat cry syndrome. Because the two children were product of mothers two separate husbands, she was suspected to be balanced carrier for a chromosome abnormality. Chromosome analysis in the mother showed that she is carrier of a balanced translocation between chromosomes 5 and 20. The mother married again, and prenatal diagnosis by amniocentesis had been carried out on her third pregnancy. The fetus was a normal male and now he is about one year old healthy baby.