A pneumothorax is a condition where the lung collapses on itself. This occurs due to air leaking into the cavity between the lungs and the chest wall pushing on the outside of the lung, causing it to collapse. There are varied types of pneuomothorax. The primary spontaneous pneumothorax (PSP) is one that occurs in the absence of any traumatic chest injury or known lung disease. It is usually precipitated by the rupture of a cyst or bleb on the lung surface. The characteristic symptom of PSP is a sharp chest pain of sudden onset leading to a tight feeling in the chest. The pain may radiate to the shoulder and increase with breathing in. Other signs and symptoms could include a sudden shortness of breath, rapid heart rate and breathing, cyanosis, cough, anxiety, and general fatigue. The annual incidence of PSP worldwide is estimated to be 18-28 and 1.2-6.0 per 100,000 males and females, respectively. Evidently, males have a higher risk for developing a PSP. Tall and thin men are at a higher risk. Other risk factors include smoking, age between 20 and 40 years, and having a family history of the condition.
A simple examination with a stethoscope is likely to give decreased or absent breath sounds over the affected lung in the case of a pneumothorax. Radiological examination confirms the diagnosis. A minor pneumothorax usually resolves on its own, without any medical intervention. More severe cases might require aspirating or removing the leaked air. In cases, where the leak does not spontaneously close, a chest surgery may be required. Individuals who have once developed a PSP have up to 40% chance of experiencing a recurrence within the next two years.
Studies of familial cases of PSPs have shed some light on the genetic basis of the condition. Some families have clearly shown an X-linked mode of transmission, whereas some show an autosomal dominant transmission with incomplete penetrance of 50% in males and 35% in females. The only gene known to be associated with PSP is the FLCN gene on chromosome 17p, which codes for the folliculin tumor suppressor protein. It is not clear, however, how mutations in this gene could influence the development of pneumothorax.