Obviously, the routine poor gene test is normal, but it gives birth to rare poor children

With the intervention of birth defects and the routine screening of poor genes before pregnancy in key populations, Guangdong, as a large province of local poverty, is effectively reducing the emergence of poor newborns through technical means. However, for the young couple from Zhaoqing, they have clearly passed the routine poverty gene test before giving birth, but they still gave birth to a daughter who is severely poor.

After free genetic testing by Guangdong Reproductive Hospital, this is the clue from the rare genes carried by the couple. The rare genes carried by the wife and the rare genes carried by the husband (different from the wife) are both passed on to the children, and they interact with each other, and then the offspring become severely impoverished. "If necessary, both husband and wife need to undergo comprehensive genetic testing for poverty." Professor Zheng Lixin, chief expert of eugenic genetics in the hospital, said.

What is thalassemia?

It is reported that thalassemia is a hereditary blood disease that seriously threatens human health and is fatal and disabling. Statistics in 2016 show that the gene carrying rate of the household registration population in Guangdong Province is about 16.8%, with an average of 1 carrier per 6 people. In addition, Guangxi, Hainan, Sichuan, Hunan and other places are also common.

Mild patients (also known as carriers of thalassemia) have no clinical symptoms, are not harmful to their health, and must be screened to be detected. Moderate to severe patients have symptoms of anemia, gray face, fatigue, slow onset of ontology, hepatosplenomegaly, and most rely on blood transfusions to maintain life. Some severe cases cause fetal oedema, often with intrauterine or postnatal death.

Thalassemia is autosomal recessive. Depending on the type of genetic defect, local poverty is mainly divided into α or β poverty. If both couples are carriers of the same type of poverty gene, there is a 25% chance of giving birth to a child with moderate/severe poverty, a 25% probability of having a healthy child, and a 50% probability of giving birth to a carrier of the poverty gene.

The mother routinely had a poor genetic test

But it gave birth to severely poor children

May 8 is the 29th World Day of Poverty, and the theme of this year's event is "Caring for the Poor, Together for the Future". In order to carry out the science popularization of thalassemia prevention and treatment and improve the public's eugenic awareness and health literacy, the case of the young couple encountered by the Eugenics Technology Center of Guangdong Reproductive Hospital is of special scientific significance.

The young couple came from a sister city, and after giving birth to their eldest daughter in early 2018, the youngest son was born again in 2019, and the children were complete, making this happy family even more joyful.

However, starting in 2020, Xiaosun and his wife found that their 2-year-old daughter had a larger belly, a dark face, and slow growth and development. Taken to the hospital for testing found hepatosplenomegaly, severe anemia. At the same time, the couple found that their youngest son's stomach also began to grow larger, and he was also tested for anemia.

"The doctor said that the child was very anemic and had to be transfused once a month." Looking at the child's painful appearance and the difficulties she will face in the future, the child's mother can't cry.

Local doctors suspect that the child has severe thalassemia. After the detection of the mutation site of the common poor gene, the little grandson and two children carried the βIVS-II.-654 pathogenic gene, and the little grandson's wife had a normal genotype.

Children with severe poverty often require regular blood transfusions and iron removal.

This is strange, carrying the same disease-causing genes for poverty, why does the little grandson have no symptoms, but the two children behave so seriously?

Therefore, Xiaosun and his wife took their children to Guangdong Provincial Reproductive Hospital for treatment. The Eugenic Genetics Department of the hospital has a Guangdong Eugenics Technology Center, which is the province's eugenics technical guidance unit, and is recently carrying out high-quality services to provide free genetic testing services for rare poor patients.

Eugenic genetics experts found that the child had a significant poverty (appearance), and after carefully examining the results of the outer hospital examination, they felt that the phenotype and genotype did not match. Judging from past experience, considering that it may be rare poverty, a comprehensive genetic test for the Xiaosun family was carried out free of charge.

As expected, xiaosun wife was found to carry the ααanti 3.7 gene after sequencing. The two children were carrying βIVS-II.-654 composite ααanti3.7 at the same time, and the problem lies here.

Professor Zheng Lixin, chief expert of eugenic genetics in the hospital, explained that thalassemia is mainly caused by the imbalance of the globin chain, and the hemoglobin molecules of normal adults are composed of 2 α chains and 2 β chains, which are composed of 4 α genes and 2 β genes to control production. If mutations or deletions in α and β genes lead to abnormal gene expression, the production of α and β globin chains can be unbalanced, resulting in different clinical features.

In some families, one of the couples is α poor carrier, the other is β poor carry, and the offspring may be a double heterozygous (light ground poverty) that α and β, but because the α and β globin chains are reduced at the same time, the proportion is not out of balance, and generally does not lead to the occurrence of severe poverty.

The special feature of this family is that the woman carries the ααanti 3.7 gene and the man's βIVS-II.-654 gene are inherited to the child, that is to say, the two children have 5 α genes to control the production of the α globin chain, 1 β gene control β the production of the globin chain, and the ratio of α gene to the β gene is 5:1, which makes the α chain and the β chain extremely unbalanced, the morphology and structure of the red blood cells are greatly affected, the deformation ability is poor, the red blood cell survival time is short, and it is easy to destroy the hemolysis in the blood vessels , causing severe clinical manifestations.

Expert reminder: if necessary, conduct comprehensive genetic testing for local poverty

Although poverty is difficult to treat, it is preventable, and pre-pregnancy and prenatal genetic diagnosis is the king of prevention! Carrying out premarital, pre-pregnancy and prenatal eugenic examinations in areas with high incidence of local poverty, and preventing the birth of severely impoverished children through medical interventions are currently internationally recognized as the primary measures and important strategies for effective prevention and control of local poverty.

Zheng Lixin, chief expert of eugenic genetics at Guangdong Reproductive Hospital, reminded that if both husband and wife carry the same type of thalassemia gene, the woman must undergo villonic retrieval, amniocentesis or umbilical cord blood after pregnancy to obtain the fetal cell line gene analysis.

Xinhua Photo

In addition to routine testing, more comprehensive genetic testing for poverty should be carried out when necessary, and the presence of rare poverty should be monitored. For example, in the family of Xiao Sun, after giving birth to the first child, the child has symptoms and signs related to land poverty, so it is necessary to go to a professional institution to further investigate, improve the detection of rare land poverty, and timely find abnormal gene carrying, in order to better guide prenatal diagnosis and avoid the risk of recurrence.

Written by: Nandu reporter Wang Daobin correspondent Cai Jiaqi Gu Heng