Cystic Fibrosis

Cystic Fibrosis (CF) is an autosomal recessive condition caused by mutations in the cystic fibrosis transmembrane regulator (CFTR) gene. There have been more than 1500 causative DNA variants (mutations) reported in the CFTR gene and different mutations may result in different clinical presentations and/or severity. The most common mutation in people of northern European ancestry is known as the delta-F508 (or DF508) and approximately 1 in 25 people with this background are unaffected mutation carriers.

The CFTR is a chloride channel which affects sodium transport across the respiratory epithelium as well as antibacterial defences. It not only has effects on the lung but may also affect the function of the pancreatic, biliary and gastrointestinal systems as specific mutation combinations being associated with male fertility.

Cystic Fibrosis can present at any age, with the more severe (generally pancreatic insufficient) forms sometimes presenting prior to birth by ultrasound manifestations such as echogenic bowel. More typically however this manifests during childhood and adolescence. Many, but not all, cases of Cystic Fibrosis in Australia can be detected by newborn screening shortly after birth.

CFTR gene testing is indicated when there is a clinical suspicion of Cystic Fibrosis, for carrier testing of a relative of a person with Cystic Fibrosis or a known genetic carrier of a CFTR gene mutation, and in cases of male infertility. Due to the high carrier frequency rate, screening may also be considered by couples considering pregnancy.

At Genomic Diagnostics we provide a test which detects a panel of 50 CFTR mutations. This represents greater than 90% of mutations in persons of northern European ancestry, and detects all mutations present at greater than 0.1% frequency in the Australian population. The panel includes mutations and variants recommended by the American College of Medical Genetics (ACMG, 2004), the American College of Obstetricians and Gynaecologists (ACOG, 2005) and the Human Genetics Society of Australasia (HGSA, 2013), plus additional multiethnic mutations.