Although rare overall, a multitude of genetic disorders affect millions of individuals worldwide. We know that genes play a role in some cancers, but how do the most common genetic disorders affect cancer risk? The answer is complex and multifaceted because it can be difficult to establish causality, even when a clear link has been identified.
Inherited gene mutations are linked to the development of breast cancer, ovarian cancer, and many other forms of the disease. The effect of genetic factors on the development of cancer has already been widely discussed in a number of publications.
Therefore, the question we’ll be exploring in this article is the extent to which the most prevalent genetic conditions affect cancer risk in early or later life. This includes diseases like sickle cell anemia and cystic fibrosis.
Sickle Cell Anemia
Sickle cell anemia (SCA) is a recessive genetic disorder caused by a mutation affecting red blood cells. These cells can develop into an abnormal crescent shape in affected individuals and cause numerous health issues. Among them are chronic pain, swelling, and anemia. It is one of the most common life-shortening genetic diseases worldwide and disproportionately affects people of Sub-Saharan African ancestry.
However, an elevated risk of leukemia (cancer of the blood cells) is one of the less well-documented health complications facing SCA patients. Better treatment is allowing more people with the disorder to lead longer lives. However, one consequence of this is that patients are living to ages at which malignancies are more likely to develop.
Lymphoma, colon cancer, and skin cancer are among other forms of the disease that people with SCA are more likely to develop than the general population. However, more research is needed before we can develop a full understanding of the factors that lead to these risks.
Cystic fibrosis (CF) is also a recessive genetic disorder that is caused by an inherited mutation affecting multiple organ systems. The lungs are particularly badly affected by the build up of thick mucus and frequent infections. Treatment has advanced significantly since the 20th century but there remains no cure. People of European ancestry are most affected, where approximately 1 in 3,000 newborns has the condition.
Like sickle cell anemia, CF patients are now living to more advanced ages than ever before. This means that more individuals are surviving to an age at which cancer is more likely to develop. The main cause for concern for people with CF is colorectal cancer. The risk is particularly elevated in people taking immunosuppressive drugs after lung transplantation.
Although the reasons for the high rate of digestive tract cancers in CF patients is not fully understood, doctors recommend that affected individuals start getting screened regularly at age 40.
Down syndrome (DS) is also a genetic disorder but differs from the first two conditions we covered in some meaningful ways. Most notably, the parents of children with DS typically have no genetic abnormalities and relatively little is known about what causes the disorder. The most established risk factor is advanced maternal age.
Screening programs have become commonplace and many parents discover the presence of DS before their child is born. Although children with the condition face physical and psychological challenges, care has improved dramatically over the course of time. Children with DS in the developed world now often live to late middle age, with a life expectancy of approximately 60 years.
Many forms of cancer are actually less common in people with DS than in the general population. This includes cancer of the lung and breast. However, these individuals also have an increased risk of other forms of the disease. Testicular cancer and certain forms of leukemia are more common in individuals with DS. However, close medical supervision can help to improve outcomes.
Fragile X Syndrome
Fragile X syndrome (FXS) is a genetic disorder caused by inherited irregularities in a gene present on the X chromosome. The syndrome can cause intellectual disability, features of autism, and mental health difficulties. Affected individuals are also more likely to suffer seizures than the general population.
Early identification of the disorder and therapeutic interventions can improve quality of life in people with FXS. Special forms of education are often required. Certain forms of behavioral therapy and medication are used to treat symptoms.
At present, little detailed research has been performed to investigate potential links between FXS and cancer. However, some evidence points to the possibility that affected people are less likely to develop cancer than the general population. High levels of the protein FMRP in breast tissue have been linked with an increased incidence of breast cancer. The protective effect of FXS may stem from the fact that the disorder is characterized by reduced levels of FMRP.
Huntington’s disease (HD) is a disorder that leads to progressive neurological deficits. Symptoms generally don’t emerge until mid-life. The vast majority of cases are inherited and the children of individuals with the HD genetic mutation carry a 50% risk of developing the disease themselves.
There are a multitude of physical and neurological symptoms. Personality changes often occur, as do impairments in thinking and cognition. Although research is ongoing, at present there is no cure for HD.
People with the disorder appear less likely than the general population to develop cancer. Researchers have attempted to pinpoint the precise reasons for this and several hypotheses have emerged. It is believed that mutated gene leading to HD also generates tiny particles that are capable of destroying cancer cells.