Examining a Lesser Known Side of Cystic Fibrosis

Nuzhat Faizah
Sophomore
School of Life Sciences
Independent University, Bangladesh

February 10th, 2018

For Raima’s family, that sweltering April summer not only brought the flares of the scorching sun, and the kath golap and krishnochura blooms, but also new hope of the arrival of a new member. Elation spread through the house after Farhan (Raima's husband) received the news that finally, the joy of parenthood was about to knock at their door because the doctors had found a surrogate mother who was ready to help the couple conceive a child.

Raima was then 35 years old. She had been diagnosed with cystic fibrosis (CF) when she was in her teen years. The signs and symptoms were not very prominent until she suddenly could not breathe properly and began to suffer from continuous coughing. While going through puberty, she suffered from malnutrition and could not gain weight despite having good meals, had issues with bowel movements, and repeatedly got lung infections. In addition, she experienced irregular menstrual cycles, and ovulatory disorders that would later lead to fertility problems.

After getting married, a gynecologist she consulted with explained that pregnancy might be deferred for female patients of CF. To understand the possible ways in which CF causes this and its other symptoms, let us delve a little into the mechanism of the disease.

Impeded chloride ion transport leads to mucus buildup. University of Utah

CF arises from mutations (changes in the genetic code) in a gene called CFTR (cystic fibrosis transmembrane conductance regulator). The gene is named after the disease, but its normal function is in fact to make a protein (also named CFTR) which acts as a channel across cell membranes to transport chloride ions into and out of the cells which helps to regulate the movement of water in tissues. This is important for maintain a certain thin consistency of mucus (a slippery substance whose function is to lubricate and shield the lining of the airways, tissues, organs and organ systems; basically, what clogs your airways when you have a cold).

Certain mutations in the CFTR gene result in changes in the structure of the membrane-spanning chloride channel, and the changes impede its normal functioning. The movement of chloride ions, and the subsequent movement of water are impeded, resulting in the production of very thick and sticky mucus in various organs. This leads to the typical symptoms of breathing difficulties by clogging up the airways with thick mucus, and malnutrition from impaired absorption of food in the bowels due to the presence of thicker mucus. Problems with nutrition and increased energy needs for dealing with the thick mucus also contribute to the irregular menstrual cycles and ovulatory issues. A lesser known consequence of CF is thicker cervical mucus. This reduces the likelihood of sperm cells successfully penetrating the cervix. These are thought to have converged in Raima’s case.

It is worth noting that the majority of women with CF are able to conceive and give live birth, but as Raima’s case demonstrates, symptoms arising from CF can seriously impede conception. Interestingly, CF’s impact on fertility is far more devastating in men; more than 90% of men with CF are infertile. These cases are due to the absence or incompleteness of a certain canal (the vas deferens) that transports sperm prior to ejaculation. The canal fails to develop properly as a result of the defective CFTR gene. To conclude on a broader note, the diverse set of symptoms resulting from a single defective gene is a neat demonstration of the pleiotropic effects of genes, which refers to the ability of many genes to affect two or more different phenotypes.

Nuzhat Faizah is a Biochemistry second-year with a never-ending passion for photography and birds. She likes to study about mental health and reproductive disorders.