Familial isolated hyperparathyroidism is a genetic condition that causes overactive parathyroid glands, leading to high levels of calcium in the bloodstream. These parathyroid glands are responsible for regulating calcium levels in the body. When they become overactive, they produce too much parathyroid hormone (PTH), which in turn increases the amount of calcium in the bloodstream.
Unlike other forms of hyperparathyroidism, familial isolated hyperparathyroidism does not have associated features such as multiple endocrine neoplasia type 1 (MEN1) or the CDC73 gene mutation. It often presents with hypercalcemia, which is an abnormally high level of calcium in the blood. This can cause symptoms such as bone pain, kidney stones, and gastrointestinal issues.
Research into the genetic causes of familial isolated hyperparathyroidism has identified some genes that can lead to the condition. Mutations in these genes can cause abnormal parathyroid cell proliferation, resulting in the overproduction of PTH. One of the identified genes is the MEN1 gene, which provides instructions for making the menin protein. In addition, a gene called CDC73 has also been associated with familial isolated hyperparathyroidism.
The inheritance pattern of familial isolated hyperparathyroidism is usually autosomal dominant, which means that a person only needs to inherit a mutation in one of the genes to develop the condition. However, in some cases, it can also be inherited in an autosomal recessive manner. Genetic testing can help determine the specific gene mutation involved.
Learning more about the causes and features of familial isolated hyperparathyroidism provides important insights into the disease and can help in the development of targeted therapies and treatments for affected individuals.
Frequency
Familial isolated hyperparathyroidism (FIHP) is a rare condition characterized by the development of parathyroid tumors in individuals with no other associated inherited features such as MEN1 syndrome. It is estimated that approximately 20-30% of individuals with hyperparathyroidism have FIHP.
FIHP is often caused by mutations in the CDC73 gene, which lead to the overactive proliferation of parathyroid cells and the development of parathyroid carcinoma. These mutations can be inherited in an autosomal dominant manner, meaning that they can be passed down from one generation to the next without other associated conditions.
More often, however, the causes of FIHP are not identified. It is believed that other genes may be involved in the development of parathyroid tumors in these individuals. Research is ongoing to learn more about these genes and their role in FIHP.
The frequency of FIHP in the general population is not well understood. However, studies have shown that the prevalence of CDC73 mutations in individuals with familial hyperparathyroidism ranges from 2% to 10%. This provides some insight into the frequency of FIHP associated with CDC73 mutations.
It is important to note that hypercalcemia and hyperparathyroidism can also be associated with other conditions, such as MEN1 syndrome or multiple endocrine neoplasia type 1. These conditions are caused by mutations in the MEN1 gene and have a higher frequency in the general population compared to FIHP.
The identification of these genes and the frequency of FIHP associated with them provide valuable information for understanding the inheritance and pathogenesis of this condition. Further research is needed to fully understand the frequency of FIHP and its underlying genetic causes.
Causes
Familial isolated hyperparathyroidism is a condition characterized by the formation of tumors in the parathyroid glands, which are located in the neck. This condition is familial, which means it can be inherited from one or both parents.
One type of tumor that can cause familial isolated hyperparathyroidism is called parathyroid carcinoma. This is a rare form of cancer that affects the parathyroid glands. While most cases of parathyroid carcinoma are sporadic, meaning they occur without a known cause, some people with familial isolated hyperparathyroidism have been found to have a specific gene mutation called the CDC73 gene.
The CDC73 gene provides instructions for producing a protein called parafibromin, which helps regulate cell growth and division. When the CDC73 gene is mutated, it can lead to the development of parathyroid tumors and the associated symptoms of hypercalcemia and hyperparathyroidism.
In addition to the CDC73 gene, other genes have also been identified in some individuals with familial isolated hyperparathyroidism. For example, mutations in the MEN1 gene have been found to cause a condition called multiple endocrine neoplasia type 1, which is characterized by the development of tumors in multiple endocrine glands, including the parathyroid glands.
Inheritance of these gene mutations can occur in an autosomal dominant pattern, meaning that a person who inherits one copy of the mutated gene from either parent can develop the condition. However, not all individuals with these gene mutations will develop hyperparathyroidism or associated tumors.
It is important to note that familial isolated hyperparathyroidism can also occur without a known genetic cause. In such cases, the exact cause of the condition is unclear, but it is thought to be related to overactive parathyroid gland function or other unknown factors.
In summary, the causes of familial isolated hyperparathyroidism can vary depending on the individual. Some cases are associated with specific gene mutations, such as mutations in the CDC73 or MEN1 genes, while others may be caused by overactive parathyroid gland function or other unknown factors. Further research is needed to better understand the underlying causes and genetic factors associated with this condition.
Learn more about the genes associated with Familial isolated hyperparathyroidism
Familial isolated hyperparathyroidism (FIHP) is a rare condition characterized by elevated levels of calcium in the bloodstream due to overactive parathyroid glands. In most cases of FIHP, these overactive glands cause a noncancerous tumor called a parathyroid adenoma. However, in some cases, the condition can lead to the development of parathyroid carcinoma, a cancerous tumor.
FIHP is typically inherited in an autosomal dominant manner, which means that a person with the condition has a 50% chance of passing it on to their children. In about 50-75% of cases, the exact cause of FIHP is unknown and is referred to as familial isolated hyperparathyroidism of unknown cause.
However, in recent years, researchers have identified several genes that are associated with FIHP. These genes include the MEN1 gene, the CDC73 gene, and the CASR gene.
The MEN1 gene provides instructions for making a protein called menin, which is involved in regulating cell proliferation and growth. Mutations in the MEN1 gene can lead to the development of parathyroid tumors and are associated with familial isolated hyperparathyroidism.
The CDC73 gene (also called the HRPT2 gene) provides instructions for making a protein that helps regulate the activity of certain genes involved in cell growth. Mutations in the CDC73 gene can cause hyperparathyroidism-jaw tumor syndrome, which is characterized by parathyroid tumors and tumors of the jaw. This syndrome is also associated with FIHP.
The CASR gene provides instructions for making a protein called the calcium-sensing receptor, which is involved in regulating the levels of calcium in the bloodstream. Mutations in the CASR gene can lead to an overactive parathyroid gland and are associated with familial isolated hyperparathyroidism.
It is important to note that not all cases of FIHP are caused by mutations in these genes. There may be other genes or factors that contribute to the development of the condition.
Learning more about the genes associated with familial isolated hyperparathyroidism can help researchers better understand the underlying causes of the condition and develop targeted treatments for affected individuals.
Inheritance
Familial isolated hyperparathyroidism (FIHP) is a condition characterized by the development of tumors in the parathyroid glands. These tumors are the result of abnormal cell proliferation and can lead to the overproduction of parathyroid hormone (PTH), causing hypercalcemia. FIHP is considered familial because it often affects multiple members of the same family.
The inheritance pattern of FIHP can be autosomal dominant, meaning that a person with the condition has a 50% chance of passing it on to each of their children. However, not all cases of FIHP are associated with specific genetic mutations. In some cases, the cause of FIHP is unknown.
Recent studies have identified several genes that are associated with FIHP. The most commonly implicated gene is called menin (MEN1), which is mutated in about 20-30% of people with FIHP. Other genes, such as CDC73, have also been found to cause FIHP when mutated.
It is important to note that not all people with FIHP have a family history of the condition. Some individuals may develop the condition due to spontaneous mutations in the genes associated with FIHP. These cases are called sporadic FIHP.
FIHP can also be associated with other conditions, such as multiple endocrine neoplasia type 1 (MEN1), which is caused by mutations in the MEN1 gene. These individuals may have additional features, such as pituitary tumors, pancreatic tumors, and neuroendocrine tumors.
Overall, the inheritance of FIHP is complex and can vary depending on the specific genetic mutations involved. Understanding the genetic basis of FIHP can help identify at-risk individuals and provide insights into the underlying causes of hyperparathyroidism.