Is Acromegaly Inherited?

DNA of a preson with acromegaly

Acromegaly is a rare chronic disease that is caused by the prolonged overproduction of the growth hormone after the fusing of the epiphyseal growth plates resulting in excessive growth in adults. The hypersecretion of the growth hormone is almost always brought about by a noncancerous tumor in the pituitary gland. Adults who have acromegaly suffer from the disease at any time. This disease is treatable in most patients but due to the slow onset and progression of the signs and symptoms, the diagnosis is usually delayed for 15 to 20 years. If left untreated, this condition can bring about serious complications and premature death. Morbidity and mortality rates are high in acromegaly due to the associated symptoms such as respiratory, cardiovascular, and cerebrovascular malignancies and disorders.

The term acromegaly is derived from the two Greek words for “extremities” and “enlargement”: akros which mean highest, topmost, at the extremities and megalos which means large, great, exaggerated. These terms actually reflect the most common physical features of the disease which is the abnormal growth of the body organs and extremities. The onset of this condition is gradual that’s why no one notices it immediately. Early symptoms include enlargement of the feet and hands and are noticeable in a change in shoe or ring sizes. Facial features become coarse and enlarged gradually. The lower jaw and the frontal bone become enlarged. A growth in the skull mass and soft tissue causes an increase in the head size. Ribs become thick and create barrel chests. Osteoarthritis may be a result of the overgrowth of cartilage and bone and as the condition progresses, the muscular weakness becomes more serious. Other symptoms may include having visual disturbances that may eventually result in blindness and headaches. There is also a possibility of having enlarged body organs like the heart, liver, kidneys, and spleen. Excessive growth hormone can also bring about changes in lipid metabolism and sugar which can eventually cause diabetes. The most serious complications of acromegaly are hypertension, diabetes mellitus, and cardiomyopathy.

Adenoma, a noncancerous tumor in the pituitary gland, is responsible for the hypersecretion of growth hormone in more than 95% of individuals with acromegaly.
The pituitary gland is a small gland located at the base of the brain which is responsible for producing several important hormones that control the functions of the body such as metabolism, reproduction, and growth and development. Growth hormone regulates the physical growth of the body. The presence of tumors in the pituitary gland compresses the pituitary gland which results in the production of excessive growth hormone and leads to acromegaly. Most of these benign tumors in the pituitary gland emerge spontaneously and are not genetically inherited. They are brought about by a genetic alteration in a single pituitary cell that results in tumor formation and increased cell division. This genetic mutation or alteration isn’t present at birth but occurs later in life.

Acromegaly is usually not inherited. A lot of the rare and isolated cases of acromegaly are not caused by underlying genetic problems that get passed through the family. Acromegaly can only be inherited in rare cases such as a part of multiple endocrine neoplasia type 1, Carney Complex, or in a condition known as ‘familial isolated pituitary adenoma’ and acromegaly, in this case, is not inherited but is rather seen as part of other genetic conditions. The gene aryl hydrocarbon receptor interacting protein (AIP) when acromegaly begins in childhood or adolescence is regarded as an awareness factor.

Based on research, there has been quite a few number of families that have inherited acromegaly. This inherited form of the disease is called familial isolated pituitary adenoma. If someone in the family has the gene for this disease, the family members have a high risk of developing the tumor in the pituitary gland and release excessive growth hormone when they are teenagers instead of when they are older which is in contrast with the usual onset of acromegaly. Since the changes occur while the bones can still grow, the extra growth hormone makes patients grow taller.

Familial isolated pituitary adenoma (FIPA) is a genetic disease characterized by the buildup of a benign tumor in the pituitary gland. Tumors that develop in the pituitary gland may release excessive levels of some hormones but there are some tumors that do not generate hormones. One of the types of tumor that can be commonly seen in FIPA is called somatotropinoma. Somatotropinoma release the growth hormone called ‘somatotrophin’ that allows the body to grow. Somatotropinoma occurring in adolescents may cause an increase in height due to the fact that the bones of the legs and arms are still growing. Somatotropinoma occurring in adults cannot cause an increase in height anymore because the growth of the long bones has stopped. The tumors in adults can cause overgrowing face, hands, and feet as well as other tissues.