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CHM

Synonyms
DXS540, GGTA, HSD-32, REP-1, TCD
External resources
Summary
This gene encodes component A of the RAB geranylgeranyl transferase holoenzyme. In the dimeric holoenzyme, this subunit binds unprenylated Rab GTPases and then presents them to the catalytic Rab GGTase subunit for the geranylgeranyl transfer reaction. Rab GTPases need to be geranylgeranyled on either one or two cysteine residues in their C-terminus to localize to the correct intracellular membrane. Mutations in this gene are a cause of choroideremia; also known as tapetochoroidal dystrophy (TCD). This X-linked disease is characterized by progressive dystrophy of the choroid, retinal pigment epithelium and retina. Alternatively spliced transcript variants have been found for this gene.

Variant counts

The variants found in rare patients tested by 3billion are classified and counted according to ACMG guidelines. The variants with over 5% variant frequency in population genome databases ( gnomAD, dbSNP, etc) are excluded.

Pathogenic
17
Likely pathogenic
0
VUS
1,648
Likely benign
2,123
Benign
137

Patient phenotypes

Proportions of phenotypes among 12 patients carrying pathogenic or likely pathogenic variants on CHM gene are displayed below.

Phenotype class
Patients in 3billion (%)
Abnormality of the eye
75%
Abnormality of the nervous system
25%
Abnormality of the musculoskeletal system
8.3%
Abnormal cellular phenotype
0%
Abnormality of blood and blood-forming tissues
0%
Abnormality of head or neck
0%
Abnormality of limbs
0%
Abnormality of metabolism homeostasis
0%
Abnormality of prenatal development or birth
0%
Abnormality of the breast
0%
Abnormality of the cardiovascular system
0%
Abnormality of the digestive system
0%
Abnormality of the ear
0%
Abnormality of the endocrine system
0%
Abnormality of the genitourinary system
0%
Abnormality of the immune system
0%
Abnormality of the integument
0%
Abnormality of the respiratory system
0%
Abnormality of the thoracic cavity
0%
Abnormality of the voice
0%
Constitutional symptom
0%
Growth abnormality
0%
Neoplasm
0%

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