All posts by yechangenetics

A Girl or a Boy? It’s In the Genes of the Father


Whether a child is a boy or a girl is actually determined by the father. In fact, the family tree of the father can be used to determine the probability of a couple having a boy or a girl, according to a study published in Science Daily in 2008.

The work by Corry Gellatly , a scientist at Newcastle University, showed that men inherit a tendency to sire more daughters or more sons from their parents. A man with many sisters is more likely to sire daughters, while a man with many brothers is more likely to sire sons.

The research involved studying 927 family trees that contained information about 556,387 people from Europe and North America going back to 1600. The study showed that whether a person is likely to have a girl or a boy is inherited.

Baby’s sex is determined by the father’s sperm. If the father’s sperm is carrying X chromosome, it combines with the mother’s X chromosome and baby a girl is conceived XX). On the other hand, if the sperm is carrying Y chromosome, a baby boy is conceived (XY).

The researchers suggest that an undiscovered gene determine whether a man’s sperm have more Y or more X chromosomes, which affects his children’s sex.



Fruit Fly Genetics Might Help Researchers Explain Why Some People Need More Sleep Than Others

The amount of sleep we need each day varies from person to person. However, the exact relationship between genetics and sleep is not clear– something that a recent study on populations of the common fruit fly might shed light on.

A small group of genes was discovered that appears to be linked to sleep variations, and which is also connected to vital cell pathways linked to memory, learning, and brain development. If the same results can be replicated into people, then it gives scientist another way for targeting sleep-related health issues like narcolepsy and insomnia, according to researchers from the National Heart, Lung, and Blood Institute (NHLBI) in Maryland.

According to lead researcher Susan Harbison, the new study is a significant step toward solving one of the key biology mysteries: the need to sleep. The involvement of diverse biological processes in the duration of sleep may help explain why some people need more sleep than others.

Using 13 generations of Drosophila melanogaster (wild fruit flies), the researchers bred one group flies that liked napping and a group of flies that didn’t require much sleep. By the end of the study, the long-sleeping flies were getting about 700 minutes of sleep each day on average. On the other hand, the short-sleeping flies settled for less than 100 minutes.

When genetic data from short and long sleepers was compared, the researchers discovered 126 differences in 80 genes that seem to be linked to the amount of sleep needed each night. With more research, such data could give the scientists clues as to the relationship between genetics and sleep.


Importance of Gene Therapy


Genes that are defective and do not work properly can cause a genetic disorder. Gene therapy is a technique that corrects defective genes responsible for the development of a disease. Researchers may use one of many approaches to correct faulty genes:
-A normal gene is inserted into a generic location in the genome to replace non-functional gene.
– Through homologous recombination, an abnormal gene is swapped for a normal gene.
– An abnormal gene is repaired through selective reverse mutation, returning it to its normal function.
– The regulation of a specific gene could be altered
Researchers have been working for many years to bring gene therapy to a clinic. Although only a few patients have received any fruitful gene therapy treatments, gene therapy cannot be said to be an impossible dream. Despite the fact that gene therapy is taking longer to reach patients, its future is encouraging. Many years of research have taught people a lot about designing effective vectors, targeting various cells, and minimizing and managing immune responses in patients. Today, numerous clinical trials are underway. Researchers are carefully testing treatments to make sure that any gene therapy developed is both safe and effective.
Some of the genetic disorders that are treated successfully using gene therapy include Severe Combined Immune Deficiency (SCID), Adenosine deaminase (ADA) deficiency, Leber congenital amaurosis, hemophilia, and blood diseases.

Is Aggression of Children Rooted in Genetics?

Recently, researchers from the Université de Montréal carried out a research on the genetic and environmental factors in childhood that may control aggressive behavior.
To compare occurrences of proactive and reactive aggressive behavior, they observed 555 sets of twins. The results show that, at age 16, both proactive and reactive aggression share many similar genetic factors. However, as the children get older, the behavior diminishes.
Proactive aggression is verbal or physical behavior meant to gain or dominates personal advantages at the expenses of others. On the other hand, reactive aggression is a defensive response to an apparent threat. While some children only show aggressive behavior, both types of aggression are closely related.
The scientist also observed that, between the ages of 6 and 12, decreases and increases in aggression seem to be influenced by environmental factors rather than genetics. Humans show the highest level of aggressive behavior towards their peers. As children grow, they learn how to control their emotions, communicate and deal with conflicts.
The study included 332 sets of fraternal twins and 223 sets of monozygotic twins, allowing scientist to determine whether differences observed in aggression are caused by genetic or environmental factors.

What You Should Know About Dimples

Dimples are considered a mark of loveliness and beauty. Dimples are genetic disorders that are caused by shortened facial muscles. They are caused by a fault in the hypodermic connective tissue that grows and develops in the course of the embryonic development.
When a person smiles, the facial skin is pulled by the shorter muscle on the face. Consequently, a slight depression is formed in the skin. The depression is what is commonly referred to as a dimple.
Dimples can be present on one or both cheeks. Like all physical traits that people possess they have two genes for them. One gene is inherited from the mother and the other one from the father. The way that a physical trait is expressed is a result of a combination of dominant genes, a recessive and a dominant gene or two recessive genes.
Dimples are passed from one generation to the next. They are inherited facial traits that parents pass to their children. Genes that create dimples are present in the sex cells before the process of reproduction. The child receives these genes from each parent. Therefore, the children have 50-100 percent chances of inheriting dimple genes if both parents have dimples. However, if only one parent has dimple genes, the probabilities of the children receiving the genes are 50 percent.
Sometimes, dimples may also be caused by spontaneous mutations that result in a cleft chin or a dent in the cheek.

Role of Genetics in Male Infertility

The human genome is a complete set of instructions for human beings. It is made up of 23 pairs of chromosomes and each pair has between 500 – 5,000 genes. Genes are responsible for particular traits such as eye color, hair color, etc. All pairs of chromosomes are the same in a man and a woman except one, the sex chromosome. Men have a Y and X chromosomes (XY) while women have two X chromosomes (XX).
Some changes to genes and chromosomes cause abnormal production of sperm or blockage to flow of sperm that leads to male infertility.
Chromosomal conditions are the most common genetic causes of male infertility. Chromosomal conditions that affect sperm production include Y chromosome deletions, Klinefelter’s syndrome, prader-willi syndrome, and other genetic conditions such as Down syndrome.
Infertility due to a gene mutation is less common. Mutations in the cystic fibrosis gene result in the congenital absence of the vas deferens. This causes blockage to flow of sperm. Other genes linked to fertility are those that prevent the testicles from descending.
It is likely that other genetic conditions will be found in future that will allow scientist to explain other causes of male infertility that currently have no known cause.

Genes Mutate Soon After Life Begins

According to researchers, hundreds of genetic mutations start to form in embryo cells soon after conception. The researchers from Yale University and Mayo Clinic said that numerous of these mutations take place as sex cells form in the embryo. That means they became part of the genome of the embryo and can be passed on to the next generation.
The study author Flora Vaccarino said that their research opens up a new perspective on human development. The research findings show that some of the human genomes do not come from the parents.
According to the researchers, these early genetic mutations are like those found in cancer. This suggests that sometimes cancer occurs as a normal by-product of cell division.
The scientist added that their findings provide new insight into causes of disease such as autism and schizophrenia. These disorders are primarily the outcome of genetic abnormalities, but no genes inherited from parents have been found to cause such cases.
In addition, the study may help to explain why one identical twin may be healthy while the other has a genetic disorder, or why some family members who carry disease-causing mutations do not get sick.