World Cystic Fibrosis Day: Genetic Testing and Reproductive Planning

Every September 8, World Cystic Fibrosis Day marks one of the most common inherited genetic conditions in the world.

Cystic fibrosis mainly affects the lungs and the digestive system. For years it was considered a strictly pediatric disease; medical advances changed that, and today the life expectancy and quality of life of those living with it have improved considerably.

There is one aspect of this condition that connects directly with reproductive medicine and gets little attention: many people are carriers without any symptoms and without knowing they can pass it on to their children.

What cystic fibrosis is

It is an inherited genetic condition caused by changes in the CFTR gene, which takes part in regulating the transport of salt and water across cells.

When that gene carries certain variants, the secretions produced by various organs become thicker than normal. That causes changes above all in:

• The lungs
• The pancreas
• The digestive tract
• The liver
• The sinuses
• The reproductive system

How it presents varies considerably from person to person.

How it is inherited

Cystic fibrosis follows autosomal recessive inheritance: developing it requires inheriting an altered copy of the CFTR gene from each parent.

When both parents are healthy carriers, in every pregnancy there is:

• A 25% chance the baby will have cystic fibrosis
• A 50% chance of being a healthy carrier, like the parents
• A 25% chance of inheriting neither associated variant

The detail that changes everything: carriers generally have no symptoms. That is why most do not know they are one.

Being a carrier and having the condition are different things

This is where a lot of confusion arises, so it is worth clarifying.

A carrier has one altered copy of the CFTR gene and also one functional copy. In most cases that healthy copy is enough for the body to work normally. Carriers lead entirely normal lives and never develop the condition.

Many people find out they are carriers only when they undergo genetic testing because of family history or during a fertility evaluation.

Carrier screening is done with a blood or saliva sample

Why it matters before trying to conceive

Genetics carries increasing weight within reproductive medicine. Many couples want to know whether there is a risk of passing on an inherited condition before trying, and cystic fibrosis is among the conditions most frequently included in carrier screening panels.

The goal is to have evidence-based information for deciding clearly, without that meaning you should walk around worried.

What carrier screening involves

These are tests that identify whether a person carries certain variants linked to inherited conditions. They are done with a blood or saliva sample.

They serve to detect changes that could be passed to children when both partners carry the same condition.

Not everyone needs the same tests. The indication depends on:

• Family history
• Ethnic background
• Medical history
• The specialist’s recommendation
• Reproductive plans

Interpreting results should always happen alongside a professional trained in genetics. A result read alone, without context, produces more anxiety than clarity.

Cystic fibrosis and fertility

The condition also influences reproductive health.

In men living with cystic fibrosis it is common to find congenital changes in the vas deferens, the structures that transport sperm. That can cause male infertility, although sperm production in the testicles is often preserved. That nuance matters, because it opens treatment options.

In women, some associated changes can influence general health and, depending on the case, present additional challenges while trying to conceive. Every patient requires individual assessment.

What options exist when both partners are carriers

When testing confirms that both partners carry variants of the same condition, alternatives exist for deciding with information:

• Genetic counseling, to understand the inheritance pattern and the real risk in each pregnancy
• Preimplantation Genetic Testing, which analyzes embryos before transfer
• PGT-M, the specific modality for monogenic conditions such as cystic fibrosis
• Clarix non-invasive prenatal testing, when the pregnancy is already underway

Which one applies depends on your case, and that conversation is part of the counseling.

Frequently asked questions

If there are no cases in my family, can I still be a carrier?

Yes, and it is the most common scenario. Because carriers have no symptoms, the variant can pass through generations without showing. No family history does not rule out being a carrier.

Is carrier screening painful or complicated?

No. It is done with a blood or saliva sample. What takes time is the interpretation, which should happen with genetic counseling.

If we are both carriers, does that mean our baby will have the condition?

No. It means there is a 25% chance in each pregnancy. There is also a 50% chance of a healthy carrier and 25% of inheriting neither variant. And options exist to reduce that risk.

Can a man with cystic fibrosis have biological children?

In many cases yes. If sperm production is preserved and the problem lies in the ducts, sperm retrieval techniques make it possible to use them in assisted reproduction treatment.

At Ingenes, genetics is part of the diagnosis

We offer genetic testing, specialized counseling, and the preimplantation diagnostic techniques that let each couple decide with real information about their case.

Knowing your family history and seeking guidance when questions arise lets you understand genetic risk before it becomes a surprise. If you are planning a pregnancy and want to explore this, a First Consultation is where the conversation starts.