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Listed most widespread genetic diseases in Azerbaijan

19 June 2013 [09:38] - TODAY.AZ
Source: AzerNews

Genetic diseases occur in different regions of Azerbaijan with varying frequency.

A heterozygous carrier of the beta-thalassemia gene is most common among apparently healthy residents of Shaki, Oghuz, Ismayilli, Goychay, Shamakhi, Agdash, Ujar, Saatly, Sabirabad an Salyan regions and scientists explain the reason differently.

"Unfortunately, due to the spread of thalassemia Azerbaijan ranks fourth in the world while ranking first is Sardinia (Italy) with 23-30 percent of the carriers of the disease; [the figure is] 17 percent in the northern and southern regions of Cyprus and 10-12 percent in some regions of Greece and Turkey," said PhD Elkhan Rasulov, geneticist at the Republican Treatment and Diagnostics Center.

If an apparently healthy person who has two heterozygotes starts a family, the risk of having a child with thalassemia for each pregnancy will be 25 percent.

"Anemia occurs with a frequency of 9 to 36.2 percent in the Lankaran-Astara region. For Gobu (Absheron region) Ehlers-Danlos syndrome is more common. Hemophilia is more common for Buzovna residents. For the residents of Guba and Gusar anemia is the most common," Rasulov said.

Ehlers-Danlos syndrome is a group of inherited connective tissue disorders, caused by a defect in the synthesis of collagen, which is an important contributor to the physical strength of skin, joints, muscles, ligaments, blood vessels and visceral organs.

Genetic diseases are caused by mutations which occur in the DNA molecule. As for the incidence of such diseases, it depends on human migration, kinship marriages and other factors.

Rasulov said it is great when those getting married, particularly relatives, undergo genetic testing.

"According to the survey I conducted among students, the parents of about 18-19 percent of respondents are relatives. Most of those who apply to us are also relatives. They pass this checkup because they are worried about their children's future," Rasulov said.

He said the most common diseases in Azerbaijan are thalassemia, hemophilia and the glucose-6-phosphate dehydrogenase deficiency (G6PD A), which causes the appearance of hemolytic crises.

"As a consequence sickle-cell anaemia (SCA) is common for the population of Gabala, Shaki, Ismayilli, Shamakhi, Agdash as well as in Narajan (Khachmaz). In the latter case the reason was that in the beginning of the last century several families from Gabala region who were carriers of the sickle-cell gene moved to Narajan village. The clinical picture of the sickle-cell disorder is very similar to that of thalassemia. It is hard to distinguish them without a special genetic analysis," the expert said.

Researches have shown that 8 percent of Azerbaijanis are carriers of the thalassemia gene. If we remember that recessive diseases occur in families where both parents are carriers of the same deleterious gene, this risk becomes clear. That is why it is so important to undergo genetic testing before marriage.

Newborn screening

Elkhan Rasulov also spoke about newborn screening.

"For the prevention of certain genetic diseases we have developed a special program which includes those diseases that affect the entire population without exception, in addition, we have a lot of genetic diseases associated with blood," Rasulov said.

Currently, there are more than 6,000 human genetic diseases. A few of them are treatable, so, their early detection and treatment can prevent the occurrence of diseases in the future. A child may be born with normal weight, but by the age of one it is possible to observe damage of his central nervous system and physical development.

Newborn screening is conducted worldwide and in 99 cases there is a positive effect. For example, 500,000 screenings a year are carried out in the Ukrainian capital Kiev to detect phenylketonuria -- disorders related to metabolism of phenylalanine, an amino acid.

Rasulov said six genetic diseases, three of which affect all populations of the world with approximately the same frequency, and three of them unfortunately, typical for the population of Azerbaijan, have been included in the newborn screening.

These six diseases are phenylketonuria, galactosemia, and deficit of the enzyme glucose-6-phosphate dehydrogenase, sickle-cell anemia, thalassemia and congenital hypothyroidism. The most common of them are thalassemia and deficiency of the enzyme glucose-6-phosphate dehydrogenase.

Newborn screening began in January 2013. Certainly, it would be better to cover all maternity hospitals and regions of the country to centralize all of the samples, so that one, two or three central laboratories would receive them and would work only in this direction, according to Rasulov.

According to Rasulov, transportation as well as the process of analysis are very simple: no later than 10 days after the birth of a baby blood is taken, and then this sample is sent to the laboratory.

"In a nutshell, this process is quite simple. This is our future, and the most gratifying is that some of these diseases - phenylketonuria and congenital hypothyroidism - are perfectly treatable," the expert said.

Rasulov said that even after treatment the patient is still a carrier of the abnormal gene, therefore, he and his spouse should undergo testing. Even if this person's spouse does not have this gene their children will be 100 percent carriers of this gene, but essentially healthy. But their children can be born sick. And if this person's spouse is apparently a healthy carrier of the abnormal gene there is a risk of 75 percent that their children will be born sick and 25 percent that they will be a carrier of the gene.

Newborn screening is a health program designed to screen infants shortly after birth for a list of conditions that are treatable, but not clinically evident in the newborn period. Some of the conditions included in newborn screening programs are only detectable after irreversible damage has been done; in some cases sudden death is the first manifestation of the disease.

This program debuted as a public health program in the United States in the early 1960s, and has expanded to countries around the world, with different testing methods in each country.

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