RDDLOGOBy Carol Guzman

This year, Rare Disease Day falls on the rarest day on the calendar: Feb. 29. Rare Disease Day helps raise public awareness about rare diseases and the impact that they have on patients’ and loved ones’ lives. Though an international event, it’s led in the U.S. by the National Organization for Rare Disorders, or NORD.

According to a 2019 study, there are more than 6,000 rare diseases around the world, and over 72% of them are genetic. Rare diseases affect people all around the world, but a person’s ancestral and genetic background can affect the likelihood that they carry certain rare conditions. It is estimated that at least 1 in 4 people of Jewish descent are carriers for so-called Jewish genetic conditions, which received their name because individuals with Jewish ancestry carry changes for these diseases 20 to 100 times more frequently than among the general population. A majority of the 51 Jewish genetic diseases included on the Sarnoff Center’s carrier screening panel qualify as “rare” diseases because they affect fewer than 200,000 people in the U.S.

In honor of Rare Disease Day, we hope to bring light to two perhaps lesser known Jewish genetic disorders: Gaucher disease and Canavan disease.

Gaucher disease type 1 is the most prevalent inherited disorder among people of Jewish decent. One in 15 people of Ashkenazi Jewish ancestry and 1 in 125 people of Sephardic Jewish ancestry are carriers for Gaucher. The disease itself affects 1 in 500 Jewish people of Ashkenazi descent.

For comparison, the better known Tay-Sachs disease has a carrier frequency rate of 1 in 27 among Ashkenazi Jews and 1 in 125 among Sephardic Jews.

Gaucher disease occurs when a mutation in the GBA gene harms an enzyme’s ability to break down certain fat molecules, which can lead to toxic levels of the fat building inside the spleen, liver and bone marrow cells. There are various Gaucher disease types because the accumulation of the fat molecule can affect the brain and body in various ways. Gaucher symptoms include a swollen belly, bone pain, anemia and bleeding or bruising. Because these symptoms are so common and vague, many cases of Gaucher go misdiagnosed.

While carriers of recessive disorders are generally healthy and do not often experience symptoms of the conditions, studies indicate that carriers with a specific mutation for Gaucher disease may also have an increased risk of developing Parkinson’s disease.

Another disease that has one of the highest carrier frequency rates in the Jewish population is Canavan disease. One in 57 people of Ashkenazi Jewish ancestry are carriers for Canavan, versus 1 in 159 people in the general population. Various mutations in the ASPA gene stop brain nerve cells from properly sending or receiving information, causing a slow degradation of the brain’s white matter. Children with the disorder typically have a larger head, poor motor skills, weak muscle tone, and difficulty eating and sleeping. Modern medicine can treat Canavan’s symptoms, but there is no U.S. Food and Drug Administration-approved cure or treatment for Canavan disease.

Unfortunately, Canavan disease is not an outlier. More than 90% of rare diseases do not have an FDA-approved treatment. On March 4, patients, their families, and medical professionals will be going to Springfield, the Illinois state capital, to meet with Illinois legislators and advocate for better opportunities and care for rare disease patients. See how you can get involved in raising awareness of rare diseases and how you can support more than 300 million affected people around the world at rarediseaseday.org.