Repulsive Guidance Molecules (RGMs) are members of a three gene family

Gene family

A gene family is a set of several similar genes, formed by duplication of a single original gene, and generally with similar biochemical functions...

 (in vertebrates) composed of RGMa

RGMA

Repulsive guidance molecule A also known as RGMa is a protein that in humans is encoded by the RGMA gene.- Function :RGMa is a repulsive guidance molecule for retinal axons. Furthermore neogenin functions as a receptor for RGM. Neogenin overexpression and RGM downexpression in the developing...

, RGMb

RGMB

RGM domain family, member B, also known as RGMB, is a protein that in humans is encoded by the RGMB gene.- Function :RGMB is a glycosylphosphatidylinositol -anchored member of the repulsive guidance molecule family and contributes to the patterning of the developing nervous system...

, and RGMc

Hemojuvelin

Hemojuvelin is a membrane-bound and soluble protein in mammals that is responsible for the iron overload condition known as juvenile hemochromatosis in humans, a severe form of hemochromatosis. In humans, the hemojuvelin protein is encoded by the HFE2 gene...

 (also called hemojuvelin).
RGMa has been implicated to play an important role in the developing brain

Neural development

Neural development comprises the processes that generate, shape, and reshape the nervous system, from the earliest stages of embryogenesis to the final years of life. The study of neural development aims to describe the cellular basis of brain development and to address the underlying mechanisms...

 and in the scar tissue

Granulation tissue

Granulation tissue is the perfused, fibrous connective tissue that replaces a fibrin clot in healing wounds. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any size it heals...

 that forms after a brain injury

Traumatic brain injury

Traumatic brain injury , also known as intracranial injury, occurs when an external force traumatically injures the brain. TBI can be classified based on severity, mechanism , or other features...

. For example, RGMa helps guide Retinal Ganglion Cell

Ganglion cell

A retinal ganglion cell is a type of neuron located near the inner surface of the retina of the eye. It receives visual information from photoreceptors via two intermediate neuron types: bipolar cells and amacrine cells...

 (RGC) axon

Axon

An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....

s to the tectum

Midbrain tectum

The tectum is a region of the brain, specifically the dorsal part of the mesencephalon . This is contrasted with the tegmentum, which refers to the region ventral to the ventricular system...

 in the midbrain

Mesencephalon

The midbrain or mesencephalon is a portion of the central nervous system associated with vision, hearing, motor control, sleep/wake, arousal , and temperature regulation....

. It has also been demonstrated that after induced spinal cord injury

Spinal cord injury

A spinal cord injury refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence...

 RGMa accumulates in the scar tissue around the lesion. Further research has shown that RGMa is an inhibitor of axonal outgrowth. Taken together, these findings highlight the importance of RGMa in axonal guidance

Axon guidance

Axon guidance is a subfield of neural development concerning the process by which neurons send out axons to reach the correct targets...

 and outgrowth.

Family members