Cushing's Disease Whole Exome Sequencing Study

Eunice Kennedy Shriver National Institute Of Child Health & Human Development

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Abstract

We are currently analyzing whole exome sequencing (WES) data with appropriate follow up to identify important genetic factors associated with Cushing's disease (CD) and related abnormal physical features. The ultimate goal is to identify a genetic variant or variants that cause CD. CD is a condition in which the pituitary gland produces inappropriately high levels of adrenocorticotropic hormone (ACTH). The ACTH stimulates the adrenal gland to produce excess cortisol, leading to clinical disease. CD is caused by ACTH secreting pituitary tumors. CD is a serious condition. It requires surgery to remove the tumor. The tumors sometimes recur in which case radiation or medical therapy is required which is not always successful. CD can cause a wide range of problems due to the high cortisol levels. These include diabetes, fractures, poor growth, and hypertension. CD can be fatal. Whole exome sequencing (WES) is a powerful tool for identifying important genetic variants associated with medical conditions. It is an efficient method of determining the genetic code (sequence) of all the regions in the genome that are translated into protein, the exons. The exons constitute about 1% of DNA, thus sequencing exons provides a large amount of information at a lower cost than sequencing the entire genome. Pediatric aged patients seen at NICHD with a confirmed diagnosis of CD are evaluated for this study. Those who have histopathologically confirmed disease in conjunction with DNA, hormonal documentation of the disease and complete clinical data are potential cases. Analysis comparing variants found in the cases with large control populations has been done. In addition, the data are being examined for copy number variants in the exons to determine if they play a role in Cushing's disease. Whole exome sequencing has now been performed on tumor tissue in patients where tumor tissue is available to determine if there are specific tumor-associated variants in the exome. These data have been analyzed in the same manner as the blood samples. In addition, samples from patients who have ectopic posterior pituitaries have been obtained and whole exome sequenced. The data have been screened using standard data sets to identify rare variants. Carney complex (CNC), is an autosomal dominant multiple neoplasia and lentiginosis syndrome. We aimed to identify risk factors associated with the occurrence and recurrence of cardiac myxomas, the predominant cause of death in CNC patients.Patients with CNC were monitored prospectively between 1995 and 2020 for the development of cardiac myxomas.Of the 319 patients studied, 136 (42.6%) developed myxomas. The mean age at diagnosis was 28.7 S.D. 16.6 years in females and 25.0 S.D. 16.4 years in males. By age 30, 35% of females and 45% of males had at least one myxoma. The CNC-related lesions, lentigines, cutaneous, mucosal, or breast myxomas, thyroid nodules, pituitary adenoma, and schwannoma were significantly more frequent (all p < 0.05) among patients with myxomas. Forty-four percent of patients had recurrences; nearly all within the first 8 and 16 years for males and females, respectively. Recurrences were more common in females. These data provide valuable information for clinical management.