Concerned About Infertility? Also Consider Whether Hereditary Genes May Affect the Next Generation

For couples planning pregnancy, fertility often becomes the top concern, such as sperm factors in men or diminished ovarian reserve in women. However, an equally important point in pre-pregnancy screening is often overlooked: whether either partner carries hereditary disease genes that may affect a child’s health and future.

With advances in medicine, many hereditary diseases can now be assessed before pregnancy instead of only after birth. Blood-based recessive carrier screening before pregnancy can evaluate more than 500 hereditary disease genes and help couples prepare earlier. This is a more complete pre-pregnancy screening strategy.

Some couples may feel hereditary disease is unlikely to affect them, especially when they are young and generally healthy. However, epidemiologic data suggest otherwise. For example, G6PD deficiency (also known as fava bean deficiency) is common in Hong Kong. Newborn screening data show that about 4 to 5 in every 100 male newborns and 3 to 5 in every 1,000 female newborns are affected. Severe G6PD deficiency can lead to acute hemolysis, which may cause permanent neurologic injury, including hearing impairment, muscle spasm, developmental delay, and in severe cases, death. This potential impact on children should not be underestimated.

What is G6PD deficiency? Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme that helps protect red blood cells. Individuals with G6PD deficiency may not show obvious baseline symptoms, but severe infection or exposure to oxidative triggers (such as certain medications or chemicals) can cause rapid red blood cell breakdown and acute hemolysis. Symptoms can include sudden pallor, shortness of breath, and rapid heartbeat. Early pre-pregnancy screening for G6PD-related genes allows families to make informed daily-life and dietary arrangements after childbirth, such as avoiding fava beans and related products, mothballs, and insect-repellent blocks.

According to 2018 research published by the University of Hong Kong, about 1 in 67 people in Hong Kong is affected by a rare disease, accounting for around 1.5% of the population. In addition to G6PD deficiency, other important hereditary conditions include Fragile X syndrome, alpha and beta thalassemia, developmental delay and autism, hearing loss (GJB2),

spinal muscular atrophy, cystic fibrosis, and Pompe disease. These can also be evaluated through pre-pregnancy hereditary gene testing. A 12 mL blood sample can test up to 301 hereditary disease genes in women and 279 in men. Testing is conducted in a US laboratory, with reports typically available in about 3 to 4 weeks.