How to diagnose rare diseases?

By : dr. Cut Nurul Hafifah, SpA

“What is my child’s diagnosis?”

“I have consulted with a lot of doctors but no one knew my child’s diagnosis”

“I feel like giving up on finding out what my child’s diagnosis is”

Parents of children with rare diseases frequently complain about these things. Diagnosing rare disease is still a challenge for doctors. They have to perform several examinations to find the correct diagnosis, but sometimes these results come out negative. This often frustrates parents and doctors. The big question is “can rare diseases be diagnosed?”

Mean length of time to diagnosis for rare diseases is 8 years. Correct diagnosis is made after visiting a minimum of 10 specialists and usually patients with rare diseases had received wrong diagnosis before the correct one is made.

Recently, rare diseases have received a small amount, yet significant, attention (thanks to on-going campaign to raise awareness about rare diseases). A survey by Global Genes in 2013 showed most physicians (60% of primary care physicians, 80% of specialists) welcomed the challenge that rare diseases brought and wanted to be part of finding a diagnosis. However, they lack sufficient time to do a workup for a rare disease even when they suspect the patient may have one.

There are more than 7000 rare diseases and 80% of them have genetic cause. Genetic tests for rare diseases consist of:

  1. Molecular genetic tests (or gene tests) study single genes or short lengths of DNA to identify variations or mutations that lead to a genetic disorder.
  2. Chromosomal genetic tests analyze whole chromosomes or long lengths of DNA to see if there are large genetic changes, such as an extra copy of a chromosome, that cause a genetic condition.
  3. Biochemical genetic tests study the amount or activity level of proteins; abnormalities in either can indicate changes to the DNA that result in a genetic disorder.

Some rare diseases can be suspected from simple laboratory test which have already been available in Indonesia. For example, Gaucher disease can be suspected from complete blood count showing anemia and thrombocytopenia. Next evaluation will be bone marrow aspiration which shows Gaucher cells. Confirmation test requires evaluation of beta-glucosidase enzyme assay which should be sent to a laboratory abroad. Another example, glycogen storage disease, can be detected by simple laboratory test, such as blood gas analysis, fasting blood glucose, lipid profile, uric acid, and blood lactate. Nevertheless, the confirmatory test requires mutation analysis.

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