Scientific research in the past twenty years has been focused on the gene, and clarified one after another, the responsible gene for a particular genetic disorder. Besides, genetic engineering technology has become a common tool for criminal investigation and paternity test. Genome project which attempts to analyze every one of genes exist on each chromosome is now moving forward.

 

Yet, it’s too early to say sophisticated mechanisms and phenomena of life are perfectly explained. Gene comprises information. And it may transformed into the protein, which, unless activates, it is meaningless. In other words, functioning of protein which is dictated by the genetic information is, of most importance. Coming back to the subject of gestational hypertension and preterm labor, what is your impression about the fact that the etiology of these new-life threatening disorders is still unclear and thereby no treatment is available?

 

In 2006, Johnson et al.in Texas USA clarified P-LAP and A-LAP were possible genes connected to gestational hypertension based on the results of QTL analysis from the disease familial trait in Australia and New Zealand over fifteen years (1984-1999). (ref.3)

 

In this literature, our study is referred in details. It is the study on P-LAP activities in gestational hypertension and reported that P-LAP is the responsible protein. I shall give some explanation for a technical term, QTL analysis.

 

 

Phenotype (appearance and characteristics) of the living creatures is determined by genetic factors and environmental factors. And with the former, there are qualitative trait and quantitative trait. Qualitative trait means the one with a small number of genes, may be one or two genes. Mendel’s law falls into this category. Quantitative trait means, on the other hand, the trait which is controlled by the sum effect of multiple genes such as those that, targeted for selective breeding of plants (e.g. rice plant).

 

Let’s review “Mendel’s law.”

The pea with “round shape seeds” and “wrinkled shape seeds” were interbred then the next generation (F1) seeds will be all “round shaped.” Next to F1 generation (F2) were bred in natural condition with a large quantity then you will find “round shape” and “wrinkled shape” with the ratio of 3 to 1.

 

As the pea contains two sets of chromosome, one from the mother plant and the other from the father plant. If the gene for “round” and that for “wrinkled” are marked W and w respectively, gene type for the parents of “round” will be marked as WW and, for the “wrinkled” as  ww. Thus, F1 will be marked as Ww. With the gene type of F2, W and w are separated into female gamates and pollen, the two meets on random chances, resulting in the ratio of 1:2:1 for WW:Ww:ww. Ww individuals will be “round seeds” because of the dominance of W over w, thereby, 1:2:1 ratio of the gene type will exhibit “round” versus “wrinkled” on the ratio of 3 (2+1) to 1.

 

What is “Quantitative Trait”?
 

Qualitative trait such as “round seeds” and “wrinkled seeds” can be clearly recognized the difference each other and it follows Mendel’s law. However, characteristics of traits that can be acquired by enumerating the number of seeds or, measuring the length of leaves are not as simple as the qualitative ones. “Qualitative Traits” are defined as these countable ones.

 

The fundamental concept of quantitative traits theory lies on Mendel’s law. However, the analytic procedure was sophisticated because of multiple genes were responsible in the phenotype effects. Owing to the computerization and the development of macro-satellite DNA marker, it has been possible to identify the position of genetic chromosomal loci which dictates quantitative traits. QTL QTL=Quantitative Trait Loci

analysis means to identify the location, number and effects of a particular trait on the chromosome.

 

 

QTL analysis means to investigate relations between DNA markers and their phenotypes (e.g. rice plants and their number of seeds). When a particular DNA marker were investigated, (Y and y for genetic disposition of the parents), genotype YY counts on average 1800,Yy = 1500significant different between phenotype YY and yy and the actual number of seeds is anticipated.

 

 

 

Here, we need to employee statistical methods to determine the deference between an averages of each group were driven by genetic factors or simply by chance. If the difference were confirmed, the position of QTL  had been determined to be located nearby DNA marker Y. “Near” means QTL and DNA marker Y are situated closer on the chromosome, in other words, “connected” in terms of heredity science terminology.

 

 

What is “ microsatellite?”

Microsatellite is genetically a repeating sequence on the genome, especially a repeating sequences of the base. Disseminated in the genome and often used as a genetic marker for DNA examination or population genetics.

 

文献

1.Rogi T et al.J Biol Chem 1996;271:56-61

2.Hattori A et al.J Biochem(Tokyo)2001;130;235-241

3.Johnson M P et al. Mol Hum Reprod 13:61-7(2007)