Rabson-Mendenhall syndrome ... (Rabson-Mendenhall syndrome) - Gen INSR.  

The Rabson-Mendenhall syndrome is a rare disorder characterized by severe insulin resistance. Insulin resistance affects the regulation of blood glucose and ultimately leads to diabetes, in which blood glucose concentrations can become harmful. In those affected, it marked resistance to insulin affects the development of many parts of the body. Signs and symptoms of the disease include lack of growth and weight gain at the expected rate, lack of subcutaneous fat, muscle atrophy, dental abnormalities, hirsutism, multiple cysts in the ovaries in women and enlarged nipples, genitals , kidneys, heart and other organs. Most affected individuals also have a skin disorder called acanthosis nigricans, in which the skin becomes thick, dark and velvety. In addition, those affected have distinctive facial features include prominent and spaced eyes, wide nose and large low - set ears.

In general, people with Rabson-Mendenhall syndrome develop signs and symptoms early in life and live into adolescence or young adulthood. Death usually results from complications related to diabetes mellitus, as a toxic buildup of ketones in the body (diabetic ketoacidosis).

The Rabson-Mendenhall syndrome is due to mutations in INSR gene, located on the short arm of chromosome 19 (19p13.3-p13.2). This gene encodes a protein called insulin receptor, which is found in many cell types. Insulin receptors are embedded in the outer membrane surrounding the cell, where they bind to circulating insulin in the bloodstream. This triggers signaling pathways that influence binding many cellular functions.

Mutations in the gene INSR reduce the number of insulin receptors reaching the cell membrane or decrease the function of these receptors. Although insulin is present in the bloodstream without sufficient functional receptors is less able to exert their effects on cells and tissues. This marked the effects of insulin resistance affects the regulation of blood glucose and results in the signs and symptoms associated with the disease.

This disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with Rabson-Mendenhall syndrome of, by complete PCR amplification of the exons of the gene INSR, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).