According to an article in MedicalXpress News Today, current research indicates that rare diseases in the United States affect 25-30 million people. The numbers keep rising and rival diseases such as diabetes (37 million people) and Alzheimer’s disease or heart failure are estimated at 6 million people. Therefore, it is fair to say that rare diseases are not as rare as we think.
In the US, rare diseases are classified as affecting fewer than 200,000 people.
The number of known diseases is also moving upward. Several years ago, the official number was 7,000 known cases of a rare disease. This year the total has unofficially increased to 10,000.
A Common Cause for Rare Disease
Previous assumptions were that genetic defects (DNA and RNA) from one parent often cause a child to be asymptomatic carriers. Researchers at the University Hospital in Basel Switzerland confirmed that every child inherits chromosome sets directly from their father plus one set from their mother. Essentially in almost every case, a human has two copies of gene alleles. Many rare diseases only take effect if both of the gene’s alleles are defective. Meaning if only one allele has been shown to be defective, the other allele can compensate and there would be no symptoms.
Prof. Mike Recher at the Basel University Medical Center and his team use examples of recessive heredity diseases posing a risk of effects on the immune system even though the defect exists in one allele only.
Prof. Recher commented that these cases were previously ignored as it was assumed that problems occurred only in the presence of two defective alleles. It is critical to note that carriers are at risk of fatal diseases as adults.
Mutations of the LIG4 Gene
When there are mutations in both alleles of LIG4 there may also be a deficit of immune system response and an increased risk of infections early in life. Earlier, carriers of one functioning LIG4 gene were considered to be asymptomatic. Now Prof. Recher’s team are reporting severe cases that resemble the originally inherited disease.
Prof. Recher recognizes that the defects may actually have been unexplained immune system disorders more often than they thought. He indicated that many unusual symptoms that occurred later in a person’s life may have been related to another inheritance pattern.
Professor Recher stressed the importance of understanding the problems at the molecular level. He explained that this can create targeted treatments with minimal side effects that fight symptoms and the cause.