Are inherited metabolic disorders possible in every pregnancy?

Not every pregnancy necessarily carries a risk of inborn errors of metabolism.

Inborn errors of metabolism refer to a group of diseases caused by gene mutations that lead to abnormalities in metabolic pathways, affecting the body's normal metabolism. These diseases are hereditary and can be transmitted through various genetic mechanisms, including autosomal dominant inheritance, autosomal recessive inheritance, and X-linked dominant inheritance. The incidence of inborn errors of metabolism is approximately 1 in 100,000, encompassing multiple types such as abnormalities in carbohydrate and lipid metabolism, protein metabolism, bone metabolism, and nervous system metabolism. The genetic probability of these diseases varies depending on the specific condition—for example, autosomal dominant inheritance carries a genetic risk of more than 50%, whereas autosomal recessive inheritance has a risk of about 10%. Additionally, there is mitochondrial inheritance, in which mitochondrial DNA is passed exclusively from the mother to her offspring, meaning all children could potentially inherit a metabolic disorder; however, this scenario is relatively rare. There is also X-linked inheritance, in which males have only one X chromosome and females have two. Therefore, if the disease-causing gene is located on the X chromosome, females are typically carriers while males are more likely to be directly affected. Under this mode of inheritance, the probability of sons and daughters being affected differs.

To prevent inborn errors of metabolism, it is recommended to undergo genetic testing before conception to determine whether either partner carries any genetic risks. If both parents are carriers of the same inherited metabolic disorder, the likelihood of their child being affected may increase. For families with a history of genetic disorders, preconception genetic counseling and relevant testing are advised.