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Genetic testing for Carney Complex (R156)

Background information

Carney complex (CNC) is a rare multiple neoplasia syndrome characterised by pigmented lesions of the skin and mucosae, cardiac, cutaneous and other myxomatous tumours, and multiple other endocrine and non-endocrine neoplasms; it can be considered a multiple endocrine neoplasia (MEN) syndrome, but one that affects a number of other tissues also.

Endocrine manifestations include primary pigmented nodular adrenocortical disease, that may cause Cushing syndrome, growth-hormone secreting pituitary adenoma or pituitary somatotropic hyperplasia which can result in acromegaly, as well as gonadal and thyroid tumors.

Non-endocrine tumours associated with Carney complex include myxomas of the heart, breast, and other sites, psamommatous melanotic schwannomas, breast ductal adenomas, osteochondromyxomas, and a predisposition to a number of malignancies from adrenal to pancreatic and liver cancer.

Predisposition to CNC tumours is autosomal dominant, and penetrance of each symptom is variable but overall is almost 100%.

Testing strategy

Clinically affected probands:

R156.1 - single gene analysis for small variants in the PRKAR1A gene

Clinical Sensitivity: Germline Pathogenic PRKAR1A variants may be found in approximately 70% of patients with a definite clinical diagnosis of CNC. Where the clinical diagnosis is less robust, PRKAR1A variants can be expected at a lower frequency, determined by the presentation

Targeted analysis for known / previously reported familial variants:

Diagnostic confirmation in individuals at risk of inheriting a previously reported familial pathogenic variant and clinically suspected of having the familial condition (R240)
Testing in clinically unaffected family members at risk of inheriting a previously reported familial pathogenic variant (R242)
Segregation studies in affected family members to aid variant interpretation (R375)
Prenatal diagnosis is not typically requested