[Pneumothorax as an early indication for a genetic disorder]

BACKGROUND

Several hereditary disorders, with highly variable and sometimes difficult to recognize manifestations, can present with a spontaneous pneumothorax. Options to perform DNA-testing have changed rapidly, as a result of which physicians of diverse disciplines are coming into contact with hereditary disorders.

CASE DESCRIPTION

Two patients with a history of multiple spontaneous pneumothoraxes were seen at the outpatient clinic of the department of Clinical Genetics. Based on family history and physical examination, a suspicion of an underlying hereditary disorder arose. Birt-Hogg-Dubé syndrome and vascular Ehlers-Danlos syndrome were diagnosed through DNA-testing. Based on this, additional screening advices were given and DNA-testing became possible in the family.

CONCLUSION

A spontaneous pneumothorax may be a manifestation of an underlying hereditary disorder. With attention to clinical symptoms and family history, physicians can contribute to timely diagnosis. In many cases this results in significant health benefits for both the patient and affected family members, such as screening for kidney cancer in the case of Birt-Hogg-Dubé syndrome.

Update of penetrance estimates in Birt-Hogg-Dubé syndrome

BACKGROUND

Birt-Hogg-Dubé (BHD) syndrome is a rare genetic syndrome caused by pathogenic or likely pathogenic germline variants in the FLCN gene. Patients with BHD syndrome have an increased risk of fibrofolliculomas, pulmonary cysts, pneumothorax and renal cell carcinoma. There is debate regarding whether colonic polyps should be added to the criteria. Previous risk estimates have mostly been based on small clinical case series.

METHODS

A comprehensive review was conducted to identify studies that had recruited families carrying pathogenic or likely pathogenic variants in FLCN. Pedigree data were requested from these studies and pooled. Segregation analysis was used to estimate the cumulative risk of each manifestation for carriers of FLCN pathogenic variants.

RESULTS

Our final dataset contained 204 families that were informative for at least one manifestation of BHD (67 families informative for skin manifestations, 63 for lung, 88 for renal carcinoma and 29 for polyps). By age 70 years, male carriers of the FLCN variant have an estimated 19% (95% CI 12% to 31%) risk of renal tumours, 87% (95% CI 80% to 92%) of lung involvement and 87% (95% CI 78% to 93%) of skin lesions, while female carriers had an estimated 21% (95% CI 13% to 32%) risk of renal tumours, 82% (95% CI 73% to 88%) of lung involvement and 78% (95% CI 67% to 85%) of skin lesions. The cumulative risk of colonic polyps by age 70 years old was 21% (95% CI 8% to 45%) for male carriers and 32% (95% CI 16% to 53%) for female carriers.

CONCLUSIONS

These updated penetrance estimates, based on a large number of families, are important for the genetic counselling and clinical management of BHD syndrome.