Choroideremia
Sequencing of the CHM gene

Genes
(full coding
region):		 CHM
Lab method: Sanger sequencing
TAT: 2-4 weeks
Specimen requirements: 2-4 ml of blood with anticoagulant EDTA

1,4 µg DNA in TE, AE or pure sterile water at 100-250 ng/µl
The A260/A280 ratio should be 1.8-2.0. DNA sample should be run on an agarose gel as a single band, showing no degradation, alongside with a quantitative DNA marker.
Ordering information: Go to online ordering or download sample submission form

Deletion/duplication analysis

Genes: CHM, RP2, RPGR
Lab method: MLPA
TAT: 4-6 weeks
Specimen requirements: 2-4 ml of blood with anticoagulant EDTA

1 µg DNA in TE, AE or pure sterile water at 100-250 ng/µl
The A260/A280 ratio should be 1.8-2.0. DNA sample should be run on an agarose gel as a single band, showing no degradation, alongside with a quantitative DNA marker.
Ordering information: Go to online ordering or download sample submission form

Indications for genetic testing:

  1. Confirmation of clinical diagnosis
  2. Carrier testing for at-risk family members
  3. Genetic counseling
  4. Prenatal diagnosis for known familial mutation

Choroideremia is an X-linked recessive chorioretinal dystrophy that mainly affects males. Symptoms evolve from night blindness to peripheral visual field loss, eventually leading to all sight loss by middle age. The vision loss is caused by degeneration of the retinal pigment epithelium, choriocapillaris, and the photoreceptor of the eye. Carrier females are generally asymptomatic, small areas of chorioretinal atrophy can be observed with fundus examination. These changes may cause night blindness and visual field loss after the second decade.

The prevalence of choroideremia is estimated between 1:50 000-1:100 000.

Choroideremia is caused by mutations in the CHM gene, mutation spectrum includes deletions, duplications, translocations, insertions, nonsense, splice-site, frameshift and missense mutations.