What are the diseases caused by non-segregation of chromosomes?
Meiosis occurs in everyone. During this division, the spindle fibers of the chromosomes are pulled towards the poles. This transfers the chromosomes to the daughter cells. Sometimes homologous chromosomes do not separate in meiosis 1 or sister chromatids in meiosis 2. This is how they move to the same pole. In this case, the chromosomes do not separate.
As a result of this event, the number of chromosomes is missing in one of the gametes compared to the others. If the chromosome number is normal in either of these two gametes, if the gamete fertilizes, the chromosome number in the offspring is either missing or too high. This non-segregation is experienced in the body and sex chromosomes. So symptoms appear and some diseases occur.
It is the condition that the 21st has chromosome 3 as a result of not being separated during meiosis. It is one of the most common chromosomal disorders. Several studies have been conducted so far and no clear factor has been found as a result of these studies. Among the known causes, the age of the mother is indicated. Mothers over age 35 are at risk.
Since most births occur in the young age of women, about 80% of people with Down syndrome are children of young mothers. Children with Down syndrome have a shorter life expectancy than normal people. Children with Down syndrome have different physical characteristics. Their eyes are slanted, their necks are thick and their fingers are short. Their mental development is somewhat behind compared to normal people.
The extra Y chromosome plays a role. People with this syndrome have longer arms than normal people. Apart from this, not many different physical properties are observed. They can grow up to 7 cm taller than the average males. These people may have a speech and learning disability. Testosterone levels are normal. Therefore, they can have children.
These people still have 1 X chromosome. Men with the syndrome are in the same situation as normal men, and this is not realized until normal adulthood. Although the testicles are not small, the amount of testosterone is also low. Some men have little or no sperm production. Some men also show up with problems like learning and speaking. Especially in childhood, motor neurons have head weakness.
Triple X syndrome
There are no obvious physical features in people with Triple X syndrome. They just get a little higher. Weakness in motor neuron skills, mild speech problems, and developmental abnormalities in the reproductive organs occur.
It is more common in girls. Drop ears, small chin and short head circumference are the most common physical characteristics. Beaches with this condition develop heart disease and can die prematurely.
It causes abnormalities in the chromosome. Most people die from miscarriage or premature birth in the womb. Defects occur in the brain and the center of the face. Fissures form around the palate and mouth.