Cystic Fibrosis Genetics

The ColumbiaDoctors genetics program provides genetic counseling for families of cystic fibrosis patients, and also coordinates follow up testing for families of infants identified through New York State Newborn Screening Program. We offer counseling in collaboration with physicians in ColumbiaDoctors pulmonologists. Our geneticists partner with the Columbia University Medical Center Cystic Fibrosis Center in following up with babies suspected to have cystic fibrosis.

What is cystic fibrosis?

Cystic fibrosis (CF) is a genetic condition that is characterized by thick, sticky mucus caused by the abnormal transport of salt within the body. Mucus plays an important role in our bodies by lubricating and protecting the lining of the organs.

In cystic fibrosis, the abnormal mucus causes blockages in organs such as the lungs and digestive tract which can lead to a variety of symptoms. The lung disease can be life-threatening and is the main cause of shortened life span.   

Main Respiratory Symptoms of Cystic Fibrosis

  • trouble breathing
  • chronic coughing
  • wheezing
  • life-threatening lung infections

Main Gastrointestinal Symptoms of Cystic Fibrosis

  • growth issues
  • weight loss
  • pancreatic insufficiency
  • CF-related diabetes

A ColumbiaDoctors multidisciplinary team provides individuals with cystic fibrosis the necessary care throughout their lives. We provide continuous therapy, medications, and monitoring for symptoms. It is important to remember that symptoms can range from severe to mild, and not every individual with CF will be affected the same way.

Genetic Causes of Cystic Fibrosis

Cystic fibrosis is due a combination of factors such as genetics and environment. In the past, the quality and length of life of patients with cystic fibrosis was poor for because of the severity of lung disease. Now with improved knowledge and treatment of the disease, individuals live well into adulthood.

Cystic fibrosis is most frequently found in the Northern European population where 1 in every 3,200 live births is affected. Other populations may also be affected but less commonly. CF is a result of a malfunctioning gene, called the CFTR gene, that regulates the transport of salt in the body. We each have two copies of the gene; one is inherited from each parent. Individuals with CF have two mutations, one mutation in each copy of the gene.

This type of inheritance is called autosomal recessive. Because each copy of the gene is inherited from a parent, this implies that each parent of an affected individual carries one mutation.

Because carriers do not have symptoms, it is difficult to know if one is a carrier unless genetic testing is performed or a couple has a child with CF, regardless of a negative family history. The carrier frequency ranges from 1 in 29 to 1 in 61 depending on ethnicity. Couples who are both carriers of CF have a 25% chance to have a baby with CF.

Cystic Fibrosis Screening Program

New York State’s Newborn Screening Program screens all babies for a number of rare diseases, including CF.  Columbia University Medical Center’s Cystic Fibrosis Center is one of the state’s referral centers for positive newborn screenings for CF.

A positive newborn screen is not a diagnostic test and therefore, requires further testing. For CF, this includes a sweat test to measure salt chloride levels in the sweat and genetic screening to look for genetic mutations in the CFTR gene. (It is important to note that positive sweat tests are diagnostic for CF, regardless of genetic testing.)

In cases where a baby has a positive sweat test but negative genetic screening, further genetic testing is needed. Our team provides genetic counseling for these families to ensure that families are educated in this process which can be confusing and difficult to process.

We also assist with coordinating genetic testing for babies and carrier testing for their family members such as parents, aunts, and uncles. Carrier testing for family members confirms which mutations they carry and also assists with reproductive planning.