Dr. Nguyen Phuong Thao of the Fetal Medicine Unit at Tam Anh General Clinic, District 7, explains that scientists have identified over 8,000 genetic disorders, but no single method can screen for all of them. Birth defects can be inherited from parents or arise from random gene mutations during embryonic development.

Dr. Thao recommends all couples undergo pre-pregnancy screening for common genetic disorders that cause serious birth defects, such as thalassemia, spinal muscular atrophy (SMA), and cystic fibrosis. If both parents carry the same disease gene, there is a 25% chance their child will have the disease, a 50% chance they will be a carrier, and a 25% chance they will be unaffected. Genetic screening allows for early detection of these risks, enabling proactive prevention and appropriate pregnancy management.

Thalassemia

This inherited recessive genetic disorder stems from defects in hemoglobin synthesis, causing hemolytic anemia. The two main types are alpha thalassemia and beta thalassemia. Children with mild cases may experience mild anemia. Severe alpha thalassemia can be fatal for the fetus due to severe anemia. Children born with severe beta thalassemia require lifelong blood transfusions and may experience complications such as stunted growth, heart failure, cirrhosis, bone deformities, and endocrine disorders.

Vietnam has over 13.8 million thalassemia carriers, representing 13% of the population, and over 20,000 individuals with severe cases requiring lifelong treatment. Each year, an estimated 8,000 children are born with thalassemia, with approximately 2,000 having severe cases.

"Vietnamese people are at high risk for carrying the thalassemia gene," says Dr. Thao, recommending pre-pregnancy screening for couples to mitigate the risk for their children.

Spinal Muscular Atrophy (SMA)

SMA is a group of genetic disorders affecting motor neurons, with a carrier rate of about 1/50. It is an autosomal recessive disorder, meaning a child with SMA inherits two mutated genes, one from each parent.

The disease gradually destroys nerve cells in the brainstem and spinal cord that control essential muscle activities like speaking, walking, breathing, and swallowing. Patients with SMA can experience muscle weakness, atrophy, difficulty with movement or respiration, and skeletal deformities, potentially leading to death. Dr. Thao notes that current treatments are costly and not always effective. Prenatal ultrasound detection is limited, identifying only severe cases, while most manifest after birth around 4-5 months of age.

Pre-pregnancy and prenatal screening for SMA allows for appropriate pregnancy management planning. Doctors can intervene immediately after birth to slow disease progression and improve the child's quality of life.

Blood test before pregnancy. Photo illustration: Tam Anh General Clinic, District 7

Cystic Fibrosis

Cystic fibrosis is an autosomal recessive genetic disorder that alters a protein in the body. The faulty protein affects glands that produce mucus and sweat. These changes cause thick, sticky mucus that can block, damage, or infect organs like the lungs and digestive system.

A fetus inheriting two copies of the mutated gene, one from each parent, will have cystic fibrosis. Children can experience serious health problems from birth, including difficulty breathing, recurrent lung infections, difficulty gaining weight, and malnutrition due to poor absorption. The disease typically progresses over time, potentially causing chronic infections, respiratory failure, pneumothorax, blocked bile ducts, and even death or infertility. Thanks to advancements in treatment, about 50% of those with cystic fibrosis live past 40.

Phenylketonuria (PKU)

PKU is an inherited metabolic disorder that causes an excess of an amino acid called phenylalanine, affecting the body's ability to metabolize protein or aspartame (artificial sweetener). Disease severity varies, ranging from severe to mild or even a benign asymptomatic form, depending on the remaining enzyme activity.

Symptoms in affected children can appear several months after birth, including a musty odor from skin and urine, fair skin, eczema, seizures, and delayed psychomotor development. In mild or moderate forms, the enzyme retains some function, reducing the risk of brain damage.

According to Dr. Thao, prenatal screening for PKU facilitates effective pregnancy management. Women with PKU should follow a special diet before and during pregnancy to minimize the risk of low birth weight, microcephaly, and congenital heart defects in the fetus. If the fetus has PKU, doctors can prepare a post-birth treatment plan, including medical protocols and personalized nutrition, to prevent intellectual disability and other complications.

Ngoc Chau