Prevention and control screening should begin before pregnancy| World Thalassemia Day

Guangdong is a high incidence area of thalassemia, and the gene carrying rate of local poverty is as high as 16.8%, that is, on average, 1 in 6 people is a carrier of the ground poverty gene. As a genetic disease, patients with thalassemia are mildly anemic and mostly die before the age of 5 if left untreated.

May 8, 2022 is the 29th World Thalassemia Day, the theme of the event is "Caring for the Poor Children, Together to the Future", aiming to advocate the whole society to join hands and take positive actions to pay attention to the poor, care for the children of the poor, and promote the healthy growth of children.

Tan Weihe, chief physician of the prenatal diagnosis center of Qingyuan People's Hospital, said that although thalassemia is difficult to treat, it is preventable and controllable. If both spouses can understand their genetic background before marriage, and do a good job of poverty screening and diagnosis before childbirth, they can effectively minimize the chances of the next generation suffering from severe poverty.

Severe poverty or fetal stillbirth intrauterine, or lifelong treatment

Tan Weihe introduced that thalassemia, referred to as ground poverty, is a hereditary hemolytic disease caused by globin synthesis disorders, named after the earliest discovery in the Mediterranean coastal countries. Ground poverty is one of the most widely distributed and affecting single-gene genetic diseases in the world, mainly found in countries bordering the Mediterranean and Southeast Asia. Guangdong, Guangxi and Hainan regions of the mainland are high-incidence areas, and the north is relatively rare.

Thalassemia is divided into many types according to the different types of globin chain deficiency, of which α and β are the two most common clinically. According to the clinical symptoms, it is divided into stationary, mild, medium and severe. Patients with quiescent and mild ground poverty are mostly clinically asymptomatic, do not interfere with daily life and work, and do not require special treatment, but may pass on abnormal genes to the next generation. Moderate-sized poor will have different degrees of anemia, severe anemia symptoms may have fatigue and weakness, liver and spleen enlargement, in the cold fever and other stress states or after taking some drugs will induce acute hemolysis and aggravate anemia, serious life-threatening. Severely α poor fetuses generally develop edema syndrome during pregnancy, intrauterine fetal stillbirth, or die shortly after birth. Children with severe β poor are generally born with no clinical symptoms, usually begin to develop gradually worsening anemia after 3 to 6 months of life, requiring lifelong blood transfusion and iron removal therapy, if not standardized treatment, patients are difficult to live to adulthood, mostly before the age of 5 years of death.

"Although it is called anemia, there is a big difference between local poverty and general anemia." Tan Weihe said that the most common anemia in general is iron deficiency anemia, which is due to the fact that the human body does not have enough iron, which may be insufficient intake, or it may be caused by excessive blood loss, and such anemia can be corrected through iron supplementation. Thalassemia is a hereditary anemia due to gene deletion or mutation, which cannot be cured with drugs at present, and can only be alleviated by repeated blood transfusions and standardized iron removal therapy. Although severe β poor can be treated by stem cell transplantation, the success rate of matching is very low.

Premarital, pre-pregnancy and prenatal visits are key to the prevention and control of poverty

Thalassemia is difficult and expensive to treat, so the key is prevention. Tan Weihe said that preventing the birth of children with moderate and severe poverty through premarital, pre-pregnancy, prenatal poverty screening and other means is the key to preventing and controlling local poverty.

Before marriage or pregnancy, couples undergo blood routine screening and hemoglobin screening, conduct genetic diagnosis for positive people, and establish health files for poor gene carriers in the confirmed area. If both husband and wife are carriers of the same type of gene, a prenatal diagnosis should be made to understand the genotype of the fetus to check whether the fetus is a severely poor child.

Tan Weihe introduced that the current methods of collecting fetal genetic material mainly include villous tissue collection by villous material extraction, amniocentesis to collect amniotic fluid cells, and percutaneous umbilical vessel puncture to collect umbilical blood. Villus extraction is usually performed at 10 to 14 weeks' gestation, amniocentesis is usually performed after 16 weeks' gestation, and percutaneous umbilical vessel puncture is usually performed after 20 weeks' gestation. If possible, villus retrieval is recommended for early diagnosis.

For couples who do not want to take risks and are financially equipped, assisted reproductive treatment (i.e. IVF) is an option to have a healthy baby. Embryos produced in vitro are tested for thalassemia genes before implantation in the mother's body, and only healthy embryos are selected for transfer.

After the birth of the fetus, the newborn is screened for thalassemia, early detection and early treatment, to prevent the disease from affecting the growth and development of the child.

Tan Weihe reminded that if a fetus is found to be severely impoverished through examination during pregnancy, it is recommended to terminate the pregnancy in time. Severely impoverished fetuses are generally malformed, and if the situation is serious, there will be fetal hypoplasia or stillbirth, and early induction measures can also avoid greater harm to pregnant women.

"We have also encountered pregnant women who refused to induce labor no matter how much they persuaded, but unfortunately, the fetus died six months after birth." Tan Weihe said that timely intervention for fetuses diagnosed with severe poverty can avoid the pain caused by severe poverty to children and families.

Do I still need to do genetic screening for poverty without symptoms?

Need, genetic testing can be used to screen for asymptomatic "hidden" carrier populations.

Poor carriers simply carry mutated genes but do not show any symptoms of anemia, or the symptoms are very mild, so they are often ignored and passed on to the next generation without their knowledge. People with no obvious symptoms may give birth to children with severe poverty after marriage, which will bring heavy economic burdens and mental pressure to society and families.

If both husband and wife are carriers of the same type of poverty gene, each pregnancy has a 1/4 chance of their children becoming severe poverty patients, and 1/2 of the probability is that they are poor gene carriers, so every couple should undergo poverty-related tests before or during pregnancy. If one of the spouses is a carrier, their children have a 1/2 chance of being carriers, and although they do not develop the disease, they can still be passed on to the next generation.

[Reporter] Liu Qiuyi

[Media Assistant] Chen Zhiyu

[Correspondent] Peng Keming

【Author】 Liu Qiuyi

【Source】 Southern Press Media Group South + client