KCNJ11-related familial hyperinsulinism

What is KCNJ11-related Familial Hyperinsulinism?

KCNJ11-related familial hyperinsulinism (FHI), also called familial hyperinsulinemic hypoglycemia type 2, is an inherited condition in which the pancreas releases inappropriately large quantities of the hormone insulin, leading to low blood sugar (hypoglycemia). When blood sugar drops to dangerously low levels, seizures and permanent brain damage may occur. If untreated, the condition could ultimately be fatal.

The pancreas normally secretes insulin in response to rising blood sugar. In people with KCNJ11-related FHI, the pancreas secretes insulin even without sugar consumption, thereby removing too much sugar from the blood.

Infants with KCNJ11-related FHI tend to have significantly low blood sugar within the first few days of life. They often require immediate infusions of the sugar glucose to prevent seizures. These newborns are typically born larger than normal and may show difficulty feeding, poor muscle tone, and breathing problems.

In some people with KCNJ11-related FHI, symptoms do not appear until later in childhood. The low blood sugar associated with the condition can also range from mild to severe depending on the individual, and varies even among members of the same family. Early and aggressive treatment is important to avoid permanent brain damage.

How common is KCNJ11-related Familial Hyperinsulinism?

The incidence of all types of FHI is approximately 1 in 25,000 to 1 in 50,000 births in most countries. KCNJ11 accounts for about 5% of all cases of FHI.

How is KCNJ11-related Familial Hyperinsulinism treated?

Treatments for KCNJ11-related FHI include dietary modification, medications, and surgical intervention. The aim of treatment is to keep the affected person's blood sugar level in the normal range to avoid brain damage.

If a child shows symptoms of KCNJ11-related FHI at birth, intravenous glucose is often given to raise and stabilize the blood sugar level. Babies may need frequent feedings with large amounts of carbohydrates, even overnight. A feeding tube may be helpful to ensure that a child gets sufficient quantities of carbohydrates and may facilitate automatic feedings overnight.

There are several types of medication to treat KCNJ11-related FHI. These are typically taken orally and/or injected several times daily.

When diet and medication do not sufficiently manage blood sugar levels, the person may require surgery to remove part of the pancreas.

After an extended period of successful treatment, many people with KCNJ11-related FHI find their symptoms lessen in severity or even go into remission.

People with KCNJ11-related FHI may find their symptoms aggravated by viral infections and should take particular precautions when they become ill, even if their symptoms have gone into remission. They should also avoid long periods of time without eating.

What is the prognosis for a person with KCNJ11-related Familial Hyperinsulinism?

The long-term outlook for someone with KCNJ11-related FHI depends upon the severity of the symptoms and the vigilance of the efforts to treat it. Permanent brain damage can occur from episodes of low blood sugar. Even with treatment, people with the disease can develop some degree of brain damage or have learning difficulties. They also may be at an elevated risk of diabetes. In the most serious cases, when the disease is not recognized and properly treated, it can be fatal. However with careful treatment, people with KCNJ11-related FHI can live normal lifespans.