CF in Asian countries

Question

My child has lung problems that seem like CF. After screening for 34 mutations he seems to have one common CF mutation. Specific tests to look for other mutations and a nasal potential measurement are ongoing. Her father comes from Indonesia and I wonder whether Asian people carry other mutations than Dutch people? And are there types of CF that are more prevalent in Indonesia compared to here?

Answer

Dear questioner,

Cystic fibrosis is caused by mutations in the CFTR gene. Every individual has 2 CFTR genes, one CFTR gene is inherited from the father, the other one is inherited from the mother. More than 1400 mutations are known in the CFTR gene and most of them cause cystic fibrosis. About 30 mutations occur with some frequency. The others are really rare. Presumably these more common mutations have been tested in your child.

Indeed in some populations, specific mutations can be more frequent than in other populations. These are called ‘ethnic-specific mutations’. The spectrum of mutations that occur frequently do differ between regions and thus certainly between continents. It is therefore indeed indicated to screen for the mutations that are common in the region of origin of the person tested (where his forefathers used to live), not in the region where that person currently lives.

There is indeed a chance that your child has a second mutation, inherited from the father, that is frequent in Indonesia or even in Asia. Unfortunately, the spectrum of frequent mutations is not known in every country and certainly not in countries where CF is less known, such as Indonesia.

It is thus more practical to do a functional test such as nasal potential difference measurement because also this test can give clues as to whether cystic fibrosis would be the correct diagnosis in your child. You can read more about this theme under ‘diagnostics’ and ‘genetics’.
Another option is to analyze the complete sequence of the second CFTR gene of your child and screen it for mutations. But this is a costly test and does not bring certainty.

Kind regards
Harry Cuppens

16.06.2010