SNP Shot: Genomic Insights

DICER1 syndrome is a genetic condition passed down through families that elevates the chance of developing various tumors, both cancerous and non-cancerous. These tumors are most frequently found in the lungs, kidneys, ovaries, and thyroid gland (located in the lower neck). Individuals affected by this syndrome may develop one or several types of tumors, and the types can vary among family members. While the risk of tumor development is increased, it's important to note that most people with DICER1-related genetic changes never actually develop any tumors, and the increase in risk compared to the general population is only moderate.

The most common tumor type in DICER1 syndrome is pleuropulmonary blastoma, characterized by tumors growing either within the lung tissue itself or in the pleura, the outer lining of the lungs. This tumor typically affects infants and young children, and is rare in adults. Pleuropulmonary blastoma is categorized into three types based on its characteristics: Type I tumors consist of air-filled pockets called cysts. Type II tumors contain both cysts and solid masses (nodules). Type III tumors are solid masses that can fill a large portion of the chest. Pleuropulmonary blastoma is cancerous, and types II and III can spread (metastasize) to other parts of the body, often the brain, liver, or bones. Patients with pleuropulmonary blastoma may also experience pneumothorax, which is an abnormal buildup of air in the chest cavity that can cause the lung to collapse.

Cystic nephroma, another potential manifestation, involves the formation of multiple, benign, fluid-filled cysts in the kidneys. In DICER1 syndrome, these cysts tend to develop early in childhood.

DICER1 syndrome is also linked to Sertoli-Leydig cell tumors in the ovaries. These tumors commonly appear in affected women during their teens or twenties. Some Sertoli-Leydig cell tumors produce testosterone, a male sex hormone, leading to the development of male characteristics in affected women, such as facial hair and a deepened voice. Irregular menstrual cycles may also occur. These tumors are generally not prone to spreading.

Individuals with DICER1 syndrome also face an increased risk of multinodular goiter, which involves enlargement of the thyroid gland caused by the development of multiple nodules (fluid-filled or solid growths). These nodules are typically slow-growing and non-cancerous. Despite the presence of these growths, the thyroid gland often functions normally. In rare instances, thyroid cancer (thyroid carcinoma) may develop in individuals with DICER1 syndrome.

Inheritance:

DICER1 syndrome follows an autosomal dominant inheritance pattern. This means that inheriting just one copy of the altered DICER1 gene is enough to cause the syndrome. However, it is essential to remember that individuals inherit an *increased risk* of tumor development; many people with DICER1 gene mutations never actually develop any abnormal growths.