Mutation compound heterozygous

Question

Compound heterozygous delta F508/3272-26A->G

Hello,

I am the mother of a 6-year-old boy with the above mutation. My question: what exactly does “compound heterozygous” mean? And what does this mutation mean?

Many thanks.

Answer

Hello,

“compound heterozygous” means that your son carries two different CFTR mutations, i.e. one of them lies in the maternal CFTR gene and the other one in the paternal CFTR gene, and both mutations lead to a loss or impairment of the chloride channel function.

Concerning the meaning of the two mutations:

F508del is the most frequent CFTR mutation worldwide and is associated with classic CF.

3272-26A>G generates a second splice point, which results in the formation of defective as well as intact gene products (chloride channels). However, the fraction of chloride channels working correctly can not be predicted, and can also vary from tissue to tissue.

Various studies have shown that patients with the F508del/3272-26A>G combination have a milder disease progression than patients with two classic CFTR mutations (e.g. F508del/F508del).

I hope this answers your question.

Kind regards,
Prof. Sabina Gallati

01.08.2012

01.08.12
It has to be taken into account in general, that mutation analysis only gives a rough direction but it has clearly to be stated, that the individual clinical course and especially the degree of lung involvement cannot be predicted according to the genotype alone, as many other genetic (modifier genes etc.) and environmental factors play a role and severity of disease differs substantially even between patients with the exact same mutations.
Therefore, it is of high importance that the individual patient is seen regularly in a certified CF center and follows his individual treatment program.
D. d'Alquen