Introduction
As noted in the article Common Health Conditions in Adults with Down Syndrome, there are many co-occurring conditions that are more prevalent in individuals with Down syndrome. It is also important to understand that there are several conditions that are less prevalent.
Cardiovascular Disease
Individuals with Down syndrome tend to have lower systolic pressure and only rarely does the pressure reach the hypertensive range.[1][2][3] This is likely due to differences in the function of the autonomic nervous system. When matched by gender and age to individuals without Down syndrome, those with Down syndrome also have lower prevalence of atherosclerosis.[2][3] Nevertheless, the GLOBAL Medical Care Guidelines for Adults with Down Syndrome recommend screening with lipid testing starting at age 40 years and following the US Preventive Services Task Force (USPSTF) guideline to use a 10-year cardiac risk calculator to determine if an adult with Down syndrome should receive statins for the primary prevention of cardiovascular disease.[4] This is addressed in more detail in the article Healthcare Guidelines for Adults with Down Syndrome.[4]
Cancers
Other than testicular cancer,[3][5] most solid tumors are less common in adults with Down syndrome.[6][7] This has implications for cancer screening, and also the evaluation of symptoms for which a solid tumor could be part of the differential.
Although individuals with Down syndrome have a decreased risk of developing most solid tumors,[2][8][9] combined analyses of nearly 30 years of cancer registry data from Denmark and Sweden indicate a modest increased risk of liver, testicular, and penile cancers compared to non-Down syndrome rates in these countries. These studies have also documented that individuals with Down syndrome do get solid tumors of the colon, testis, breast, liver, penis, stomach, brain, endometrium, parathyroid, kidney, and small intestine.[9] There have been additional case reports of male breast cancer in adults with Down syndrome.[10]
As such, primary care clinicians of adults with Down syndrome should remain alert for underlying hematologic or solid tumor neoplasms. Solid tumor screening should be dictated by clinical symptoms, family history, and risk factors. In situations that would raise one’s suspicions for hematologic malignancies, such as easy bruising, petechiae, fatigue, or change in eating patterns, clinicians should order complete blood counts and refer to specialists as appropriate.[11][12] Although the risk of leukemia in children with Down syndrome (< 5 years) is 18-fold higher than in those without Down syndrome, this risk drastically decreases over time. In one study, which reported 36 cases of leukemia in children, there were no cases after age 30.[8]
Asthma
While individuals with Down syndrome may develop wheezing, asthma is less common.[13] Differences in the function of the autonomic nervous system and a possible lower prevalence of allergies may contribute to lower asthma prevalence.
Fertility and Reproductive Health
Reproductive health for individuals with Down syndrome is an area that is often poorly addressed by clinicians.[14] Both men and women with Down syndrome can experience delays in puberty and have decreased fertility compared to their peers without Down syndrome.[15][16][17] However, women with Down syndrome are able to conceive and bear children.[18][19] Deciding whether pregnancy in a woman with Down syndrome is considered high-risk will depend upon her cognitive level and co-occurring medical conditions (e.g., cardiac, thyroid, hepatic diseases, and/or seizure disorder). Men with Down syndrome are typically considered sterile because of hypoplastic germ cells, elevated levels of both luteinizing hormone (LH) and follicle-stimulating hormone (FSH), lower levels of testosterone, and smaller testicular volume.[20][21] There are, however, case reports of children being fathered by men with complete trisomy 21.[22][23]