What Is Rhabdoid Tumor Predisposition Syndrome?
RTPS, or rhabdoid tumor predisposition syndrome, is a rare genetic condition that is characterized by the presence of a high risk of developing cancerous growths called rhabdoid tumors. These tumors commonly affect infants and children. These tumors are highly aggressive and spread at a faster rate. Malignant rhabdoid tumors can affect any location of the body but commonly target the CNS - brain and spinal cord (central nervous system). These tumors are called rhabdoid tumors because the affected cells typically resemble rhabdomyoblasts, present in the embryos (before birth) and which turn into skeletal muscles later (muscles required for body movement). This article highlights the tumor's prevalence, causes, symptoms, and management.
What Is the Prevalence of Rhabdoid Tumor Predisposition Syndrome?
RTPS tumor is a very rare genetic tumor that affects infants and children less than three years of age. It mostly affects the children in the first year of age.
What Are the Common Sites that Are Affected by Rhabdoid Tumors?
RTPS tumors can affect any location of the body but commonly involve the central nervous system. Different anatomical locations impacted by RTPS are
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Cerebellum (more than 50 %).
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Head and neck.
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Paravertebral muscles.
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Liver.
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Bladder.
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Mediastinum.
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Kidney.
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Heart.
What Are the Causes of Rhabdoid Tumor Predisposition Syndrome?
Rhabdoid tumor predisposition syndrome is a genetic condition caused by mutation of the gene SMARCB1 (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1). These genes are present throughout the body, repair DNA (deoxyribonucleic acid), and control and divide cells.
What Are the Clinical Features of Rhabdoid Tumor Predisposition Syndrome?
RTPS tumors present with the following signs and symptoms:
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Renal dysfunction (kidney dysfunction).
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Abdominal masses.
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Multiorgan involvement.
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Neurological signs and symptoms such as paralysis of nerves.
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Difficulty in breathing.
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It may also affect the soft tissues of the lungs and livers.
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Congenital presentation (within the first 28 days of life).
How Is Rhabdoid Tumor Predisposition Syndrome Diagnosed?
Different diagnostic techniques used to diagnose RTPS are:
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Family History: As the disorder is mostly hereditary, the doctor usually records a detailed family history of the patient. The chances of tumors are more prevalent in children with a similar family history.
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Molecular Genetic Testing: Molecular genetic testing involves the collection of samples of blood from WBC (white blood cells), from which DNA is isolated. Two identical copies of the SMARCB1 gene are made from the isolated sample and then analyzed using various methods.
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Prenatal Testing: CVS or chorionic villus sampling method or amniocentesis is used for the isolation of DNA from the cells of the embryo. The DNA is analyzed later for alteration in the SMARCB1 gene. Proper genetic counseling is done by the specialist to the parents on whether to continue with the pregnancy term or to terminate the pregnancy.
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Preimplantation Genetic Diagnosis (PGD): For the parents who have used IVF (in-vitro fertilization) for pregnancy, those embryos can be used for testing genetic disorders before transferring them into the uterus.
How Is Rhabdoid Tumor Predisposition Syndrome Managed?
RTPS is managed by the multidisciplinary approach (doctors from different specializations such as oncologists, geneticists, and surgeons) by the following method:
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Genetic Counseling: Genetic counseling is usually advised for couples who are identified with the risk through genetic testing. Counseling helps to provide information about the hereditary characteristics of RTPS and guides the affected individual's family about the risk.
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Regular Medical Monitoring: Regular monitoring of the patients for the prompt detection of the tumor is required with the help of radiographic analysis such as MRI (magnetic resonance imaging) and CT scan (computed tomography). Monitoring of the CNS (brain and spinal cord) is also crucial.
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Surgical Intervention: A few tumors can be removed surgically if it is feasible and safe.
The surgery technique used depends on the tumor's size, extent, and location.
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Chemotherapy: Chemotherapy is used in two sessions; one session is given before the surgical intervention to shrink the tumors, followed by the second session of chemotherapy to treat any residual disease to prevent the risk of recurrence of the cancer. Different chemotherapeutic agents are selected based on the tumor type, extent, and site.
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Radiation Therapy: Radiation therapy is used specifically for tumors that cannot be completely eliminated surgically or for those types of tumors that are at higher risk of recurrence.
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Targeted Therapies: Currently, research is ongoing on investigating the efficiency of specific targeted therapies to treat rhabdoid tumors' genetic and molecular basis.
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Supportive Care: Supportive and preventive care measures to manage signs and symptoms as well as complications associated with the tumors or their management are also crucial.
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Clinical Trials: The specialist may recommend participating in a few clinical trials, especially for individuals with refractory or recurrent disease, to investigate novel management approaches.
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Long-Term Follow-Up: Long-term follow-up care is important to monitor for potential delayed side effects of the treatment continuously, as well as the formation of new tumors or recurrence of the old ones.
What Is the Prognosis of Rhabdoid Tumor Predisposition Syndrome?
The prognosis of RTPS tumors varies depending on the size, extent, and location of the cancerous growth. Individual responses for different cases and for different treatment interventions also impact the prognosis of the disease.
Conclusion
Rhabdoid tumor predisposition syndrome (RTPS) is a rare and inherited genetic disorder characterized by an increased susceptibility to the development of aggressive rhabdoid tumors. This syndrome is primarily associated with germline mutations in the SMARCB1 gene, a key regulator of chromatin structure and gene expression. Because of the rarity and complexity of RTPS, a multidisciplinary approach is essential for accurate diagnosis and management. Early detection and intervention, often involving surgery, chemotherapy, and other therapeutic modalities, are crucial for improving outcomes. Genetic counseling plays a significant role in guiding affected individuals and their families, providing information about the hereditary nature of the syndrome, and facilitating appropriate medical monitoring. Ongoing research is essential for a deeper understanding of the genetic mechanisms underlying rhabdoid tumor predisposition syndrome and the development of more effective therapeutic strategies.
