Choroideremia

Choroideremia
Other names	CHM, Tapetochoroidal dystrophy
An example pedigree chart, showing the inheritance of a sex-linked disorder like choroideremia.
Specialty	Ophthalmology
Symptoms	Progressive vision loss
Usual onset	Childhood
Duration	Chronic
Causes	Genetic
Diagnostic method	Genetic testing, family history, fundus examination

Choroideremia (/kɒˌrɔɪdɪˈriːmiə/; CHM) is a rare, X-linked recessive form of hereditary retinal degeneration that affects roughly 1 in 50,000 males. The disease causes a gradual loss of vision, starting with childhood night blindness, followed by peripheral vision loss and progressing to loss of central vision later in life. Progression continues throughout the individual's life, but both the rate of change and the degree of visual loss are variable among those affected, even within the same family.^[1]

Choroideremia is caused by a loss-of-function mutation in the CHM gene which encodes Rab escort protein 1 (REP1), a protein involved in lipid modification of Rab proteins. While the complete mechanism of disease is not fully understood, the lack of a functional protein in the retina results in cell death and the gradual deterioration of the retinal pigment epithelium (RPE), photoreceptors and the choroid.^[2][3]

As of 2019, there is no treatment for choroideremia; however, retinal gene therapy clinical trials have demonstrated a possible treatment.^[4]