Cystic fibrosis becoming broad spectrum of illness

DEAR DR. ROACH: My mother was diagnosed with cystic fibrosis as an adult. She has always taken a long time to recover from lung illnesses, and has had episodes of bronchitis and occasionally pneumonia. She was told that she has an unusual gene mutation. What is my risk?

ANSWER: Cystic fibrosis is a multisystem condition affecting mostly the respiratory and gastrointestinal systems.

It is caused by one of many mutations in the cystic fibrosis gene (called CFTR), which codes for a protein whose job is to regulate the movement of chloride ions across receptors.

When this protein isn’t working properly, secretions can become thick, and over time they can damage small structures of the body, especially in the pancreas, upper airway (including sinuses) and lungs.

Increasingly, we are recognizing that CF is a broad spectrum of illness. Some of the mutations in the CFTR gene are very serious and cause the classic form of CF, usually diagnosed by the age of 2.

However, other abnormal genes, such as what your mother seems to have, cause a much milder disease that may not be recognized as CF until later in life (if ever).

CF should be considered in any person with recurrent sinus and pulmonary disease.

Cystic fibrosis is a genetic condition, but since there are two copies of the CFTR gene, it acts as a recessive trait, meaning that a person needs to have two abnormal copies of the gene in order to have symptoms of the disease.

Thus, both of your mother’s parents must have had a genetic mutation. That means you are certain to have inherited a genetic mutation from your mother (since both of her copies are abnormal), but if your father’s genes were normal, you would be a carrier for CF (although the specific mutation you inherited confers greater or lesser risk).

I contacted an expert in CF, Dr. Rodney Folz at Case Western Reserve University, who recommended you consider genetic testing for family planning. Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.