Genetic diseases are those that are caused by abnormalities in the genetic material in the early embryonic stage of fetal development. Congenital diseases are those that are evident at birth or early infancy, regardless of the cause.
Before reviewing the similarities and differences between these 2 labels, let’s explore genes and how they cause disease.
Understanding genes
A gene is a unit of hereditary information. Each human has approximately 30,000 genes. Each gene controls a different biologic activity: from embryonic and fetal growth and development to personality to height and eye color.
Genes are carried by DNA, which is wound into little packages called chromosomes. Every person has 2 copies of each chromosome: 1 chromosome is inherited from each parent. (Humans have 23 pairs of chromosomes for a total of 46.) From conception, every person, in each cell of his body, carries copies of all the genetic material he will have for the rest of his life.
If something goes wrong in 1 of the thousands of genes or if the number or structure of 1 of the 46 chromosomes is altered, a genetic disease can result.
Understanding heredity
Genetic diseases may or may not be inherited from a parent. New mutations (changes or alterations) to genes or chromosomes can happen at any time, so a new genetic disease may appear in a person with no family history of the disease.
Many genetic diseases are apparent at birth, so they are also congenital diseases. But, many congenital diseases have no hereditary component, so they are not genetic diseases. For example, a defect or malformation resulting from a maternal infection or exposure of the fetus to a drug or harmful chemical during pregnancy is considered a congenital disease. Roughly half of congenital diseases cannot be linked to any specific cause.
Some genetic diseases are inherited from 1 or both parents but are not evident until later in life, so they are not congenital. Huntington’s disease and Tay-Sachs disease are genetic diseases, but affected people may not show signs or symptoms of them until sometime during childhood or adulthood. (There are some scientists who prefer to note that any problem in your genes is there from before birth, so, technically, the condition is “congenital” as well as “genetic,” but others maintain that congenital disease are evident [with manifested signs and/or symptoms] at birth.)
Some diseases may simply show “clustering” among families, even without a genetic component. Hepatitis B often appears in many members of the same family, but there is no known genetic cause of the infection.
Examples of common genetic diseases include:
- Cystic fibrosis
- Down syndrome
- Hemophilia
- Duchenne muscular dystrophy
- Thalassemia
Examples of common congenital disorders include:
- Cleft lip and/or palate
- Cerebral palsy
- Fragile X syndrome
- Down syndrome
- Spina bifida
- Cystic fibrosis
- Heart conditions
Understanding risk
The best way to prevent genetic and congenital diseases is to fully understand your risks. There are tests for some genetic and congenital diseases that can be conducted before conception and during pregnancy. Such tests will allow parents to fully understand what, if any, diseases or conditions their future children may inherit or experience. Pre-conception counseling may be advised for parents who are at risk for passing on genetic diseases.
Low income may cause some congenital diseases, implying that lack of healthcare access and resources, poor nutrition, and exposure to toxins may increase the risk of diseases and malformations in growing fetuses. The best way to prevent congenital disorders is to eat a healthy diet before and during pregnancy (including taking vitamins recommended by your healthcare provider); avoiding alcohol, smoking, and illicit drug use; controlling other chronic conditions you may have such as diabetes or high blood pressure; avoid exposure to potentially harmful chemicals such as cleaning products and pesticides; and getting vaccinated against common infections.
