SNP Shot: Genomic Insights

Type A insulin resistance syndrome is a rare condition marked by extreme insulin resistance, where the body's tissues struggle to respond to insulin. Insulin's usual role is to regulate blood sugar by facilitating the transfer of glucose from the bloodstream into cells for energy. In this syndrome, impaired insulin response disrupts blood glucose control, leading to diabetes mellitus, a state of dangerously high blood sugar.

The severe insulin resistance also causes the other signs and symptoms of type A insulin resistance syndrome. In females, these features usually emerge during adolescence. Many do not start menstruating by age 16 (primary amenorrhea) or experience infrequent and light periods (oligomenorrhea). They may develop ovarian cysts and excessive hair growth (hirsutism). Acanthosis nigricans, a skin condition causing thick, dark, velvety patches in skin folds, is also common. Unlike most individuals with insulin resistance, females with this syndrome are typically not overweight.

The symptoms in males with type A insulin resistance syndrome are often less pronounced. Some males might only experience low blood sugar (hypoglycemia), while others may also have acanthosis nigricans. Often, affected males are diagnosed when they develop diabetes mellitus later in life.

Type A insulin resistance syndrome is categorized as one of the inherited severe insulin resistance syndromes, which includes conditions like Donohue syndrome and Rabson-Mendenhall syndrome, forming a spectrum of disorders. Type A insulin resistance syndrome is on the milder end of this spectrum, with symptoms appearing later in life, generally not posing an immediate threat to life.

Inheritance:

Type A insulin resistance syndrome can be inherited in two ways: autosomal dominant or, less frequently, autosomal recessive. In autosomal dominant inheritance, only one copy of the mutated gene is necessary to cause the disorder. An affected individual might inherit the gene from a parent who also has the condition or the mutation might be new in the affected person, without a family history. In autosomal recessive inheritance, both copies of the gene must be mutated for the disorder to manifest. In this case, both parents carry one copy of the mutated gene but usually do not exhibit symptoms.