SNP Shot: Genomic Insights

Autosomal dominant hypocalcemia is a condition where blood calcium levels are abnormally low (hypocalcemia). Individuals with this condition may also experience imbalances in other blood components, such as elevated phosphate (hyperphosphatemia) or reduced magnesium (hypomagnesemia). Some affected individuals also have reduced levels of parathyroid hormone (hypoparathyroidism), a hormone vital for regulating blood calcium. These calcium and other molecular imbalances can cause various signs and symptoms; however, about half of those affected experience no health problems.

Common symptoms of autosomal dominant hypocalcemia include muscle spasms in the hands and feet (carpopedal spasms), muscle cramps, abnormal tingling or prickling sensations (paresthesias), and heightened nerve and muscle excitability (neuromuscular irritability) throughout the body. In more severe cases, individuals may develop seizures, often beginning in infancy or childhood. These symptoms may only appear during times of illness or fever.

Some individuals with autosomal dominant hypocalcemia exhibit high levels of calcium in their urine (hypercalciuria). This can lead to calcium deposits in the kidneys (nephrocalcinosis) or the formation of kidney stones (nephrolithiasis), both of which can impair kidney function. In some instances, abnormal calcium deposits can occur in the brain, typically within the basal ganglia, which are structures involved in controlling movement.

A small percentage of severely affected individuals display features of Bartter syndrome, a kidney disorder, in addition to hypocalcemia. These features may include low potassium (hypokalemia) and magnesium levels, as well as increased levels of the hormone aldosterone (hyperaldosteronism) in the blood. This imbalance can also increase the blood's pH, a condition known as metabolic alkalosis. The combination of these features is sometimes called autosomal dominant hypocalcemia with Bartter syndrome, or Bartter syndrome type V.

Autosomal dominant hypocalcemia is categorized into two types based on the specific gene that causes the condition. However, the signs and symptoms of both types are generally the same.

Inheritance:

This condition follows an autosomal dominant inheritance pattern. This means that only one copy of the mutated gene in each cell is sufficient to cause the disorder. Typically, an affected individual inherits the mutated gene from a parent who also has the condition. However, in a small number of cases, the condition results from a new gene mutation and occurs in individuals with no family history of the disorder.