FLCN Gene

Birt-Hogg-Dubé syndrome is a rare disorder that affects the skin and lungs and increases the risk of certain types of tumors. Its signs and symptoms vary among affected individuals.

Birt-Hogg-Dubé syndrome is characterized by multiple noncancerous (benign) skin tumors, particularly on the face, neck, and upper chest. These growths typically first appear in a person's twenties or thirties and become larger and more numerous over time. Affected individuals also have an increased chance of developing cysts in the lungs and an abnormal accumulation of air in the chest cavity (pneumothorax) that may result in the collapse of a lung. Additionally, Birt-Hogg-Dubé syndrome is associated with an elevated risk of developing cancerous or noncancerous kidney tumors. Other types of cancer have also been reported in affected individuals, but it is unclear whether these tumors are actually a feature of Birt-Hogg-Dubé syndrome.

Potocki-Lupski syndrome is a condition that results from having an extra copy (duplication) of a small piece of chromosome 17 in each cell. The duplication occurs on the short (p) arm of the chromosome at a position designated p11.2. This condition is also known as 17p11.2 duplication syndrome.

Infants with Potocki-Lupski syndrome may have weak muscle tone (hypotonia) and swallowing difficulties (dysphagia) that lead to feeding problems. Some affected babies do not grow and gain weight at the expected rate (described as failure to thrive), and children with this condition tend to be shorter and weigh less than their peers. About 40 percent of babies with Potocki-Lupski syndrome are born with a heart defect, which in some cases is life-threatening.

Babies and children with Potocki-Lupski syndrome have delayed development, including delayed speech and language skills and gross motor skills such sitting, standing, and walking. As they get older, affected individuals have intellectual disability, which is usually mild to moderate, and ongoing difficulties with speech. Potocki-Lupski syndrome is also associated with behavioral problems, which can include attention problems, hyperactivity, compulsive or impulsive behaviors, and anxiety. Many people with this condition have features of autism spectrum disorder, which affects social interaction and communication.

Other signs and symptoms of Potocki-Lupski syndrome can include vision and hearing problems, dental and skeletal abnormalities, and abnormal kidney development and function. Many affected individuals have problems with sleep, including short pauses in breathing during sleep (sleep apnea) and trouble falling asleep and staying asleep. The condition can also have subtle differences in facial features, including outside corners of the eyes that point downward (down-slanting palpebral fissures), a triangular face with a broad forehead and a small jaw (micrognathia), and widely spaced eyes (hypertelorism).

Primary spontaneous pneumothorax is an abnormal accumulation of air in the space between the lungs and the chest cavity (called the pleural space) that can result in the partial or complete collapse of a lung. This type of pneumothorax is described as primary because it occurs in the absence of lung disease such as emphysema. Spontaneous means the pneumothorax was not caused by an injury such as a rib fracture. Primary spontaneous pneumothorax is likely due to the formation of small sacs of air (blebs) in lung tissue that rupture, causing air to leak into the pleural space. Air in the pleural space creates pressure on the lung and can lead to its collapse. A person with this condition may feel chest pain on the side of the collapsed lung and shortness of breath.

Blebs may be present on an individual's lung (or lungs) for a long time before they rupture. Many things can cause a bleb to rupture, such as changes in air pressure or a very sudden deep breath. Often, people who experience a primary spontaneous pneumothorax have no prior sign of illness; the blebs themselves typically do not cause any symptoms and are visible only on medical imaging. Affected individuals may have one bleb to more than thirty blebs. Once a bleb ruptures and causes a pneumothorax, there is an estimated 13 to 60 percent chance that the condition will recur.