Lynch Syndrome
It is named after Dr. Harry Lynch, who described this syndrome in 1960s. Lynch syndrome is also known as Hereditary Non-Polyposis Colorectal Cancer (HNPCC). Pretty mouthful huh!
Even though it is called so, it is however a genetic condition that involves high risk of CRC and a variety of cancers, also it no polyps are seen in it. It is a relatively common inherited form of cancer.
Lynch syndrome is an Autosomal dominant disease that implies once expression of an allele has the ability to cause this condition. Since it is a genetic condition, it has 50 % chances of getting their children affected by the disease.
The important point here is that if it not passed to the children, it would not be passed down to the grandchildren as it doesn’t skip generations.
It is of two types:
- Lynch Syndrome Type-1 (HNPCC 1) Example – Colon cancer
- Lynch Syndrome Type- 2 (HNPCC 2) Example – Colorectal cancer, endometrial cancer, ovarian cancer, etc.
There are relatively high risks of colorectal (50%) and endometrial cancer (60%). However, there is a long drawn out list of cancers that are seen in patient affected by lynch syndrome like stomach cancer, uterine cancer, pancreatic cancer, bile duct cancer, small intestinal cancer, urinary tract cancer, etc.
Generally, the age of its onset depends on the type of cancer, but the age of around 44 to 65 years is estimated in Lynch syndrome, which is quite younger than normal age for cancers.
How does it happen?
Lynch syndrome is basically caused by DNA mismatch repair proteins.
Throughout our life, we get exposed to various things like smoking, alcohol abuse, UV radiations, etc. that can eventually cause some mutations in your DNA while the cell division process, causing the mismatch of DNA nucleotide sequence. To fix these mismatches or errors mismatched repair proteins correct the previous errors, acting as the editors.
Genes named MLH1, MSH2, MSH6 and PMS2 are mismatch repair genes. Having a mutation in these genes implies that you have a lynch syndrome.
How would I know if I have Lynch Syndrome?
The signs or symptoms that would give you a hint of your family might have Lynch syndrome are:
- Colon or endometrial cancer seen in individuals in early age (under 50 year age).
- Colon or endometrial cancer with an additional cancer like ovarian cancer, stomach cancer, etc. (the lynch syndrome spectrum of cancers).
- Two or more relatives in the family having cancer from lynch syndrome spectrum.
How is Lynch Syndrome diagnosed?
If your doctor observes you meeting certain criteria, some screening tests will be performed. In addition to the previously listed 4 genes, there is a gene named EPCAM which if mutated implies the existence of Lynch syndrome.
There is a wide range of screening techniques for detecting Lynch Syndrome, since there is wide range of cancers involved with this disease. Different procedures or screening techniques are adopted in varying cancers. For example:
- Colonoscopy for Colorectal cancers
- USG for uterine cancer
- Endoscopy for intestines