User login

Enter your username and password here in order to log in on the website:

Forgot your password?

Please note: While some information will still be current in a year, other information may already be out of date in three months time. If you are in any doubt, please feel free to ask.

Mutations F508del / Q220X

Our three month old son was diagnosed at birth. It has the mutations F508del and Q220X.
I would like to know how people with its two mutations evolve.
Thank you

The mutations F508del and Q220X are each a “CF causing” mutation that is to say causing cystic fibrosis when combined with another “CF causing” mutation. This is the case for your child.

The mutation F508del is the most frequent mutation of the cystic fibrosis gene (the CFTR gene): it is present in almost 75% of patients and in duplicate (homozygous F508del/F508del) in about 40% of patients. It is a class II mutation that results in an absence of CFTR protein because it is destroyed by the cell immediately after being synthesized and therefore cannot reach the membrane and function as a chloride channel.

The mutation Q220X is much rarer. It is found associated with the F508del mutation in only 46 of the nearly 100,000 patients worldwide recorded in the CFTR2 database of the Johns Hopkins Hospital in Baltimore, Maryland, USA (see link to the site in English ). It is a class I mutation which results in an absence of CFTR protein due to a premature termination of its synthesis in the nucleus of the cell (hence the name "Stop mutation").

These patients:
- have a sweat chloride of 104 mmol / L on average;
- are almost all (45/46) insufficient pancreatic (requiring oral pancreatic enzymes)
- have a respiratory impairment whose severity is however variable according to the patients.

It should be recalled that these important statistical data do not, however, make it possible to predict the course of the disease in a given individual. Each situation is unique because if the evolution depends on the mutations of the CFTR gene it also depends on many other environmental factors (lifestyle, pollution ...) and other genetic factors that can modulate the dysfunction of mutations of the CFTR gene.

Do not hesitate to speak with the CF Centre doctor who follows your child and who can refer you to a clinic genetic consultation if you wish.

Hoping to have answered your question.
Best wishes

Gilles RAULT, MD
Roscoff CF Centre, ildys Foundation