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BLM

Synonyms
BS, MGRISCE1, RECQ2, RECQL2, RECQL3
External resources
Summary
The Bloom syndrome is an autosomal recessive disorder characterized by growth deficiency, microcephaly and immunodeficiency among others. It is caused by homozygous or compound heterozygous mutation in the gene encoding DNA helicase RecQ protein on chromosome 15q26. This Bloom-associated helicase unwinds a variety of DNA substrates including Holliday junction, and is involved in several pathways contributing to the maintenance of genome stability. Identification of pathogenic Bloom variants is required for heterozygote testing in at-risk families.

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
25
Likely pathogenic
5
VUS
5,955
Likely benign
2,165
Benign
1,169

Patient phenotypes

Proportions of phenotypes among 30 patients carrying pathogenic or likely pathogenic variants on BLM gene are displayed below.

Phenotype class
Patients in 3billion (%)
Abnormality of the nervous system
40%
Abnormality of head or neck
23.3%
Abnormality of the cardiovascular system
23.3%
Abnormality of the eye
23.3%
Abnormality of the integument
20%
Abnormality of blood and blood-forming tissues
16.7%
Abnormality of limbs
13.3%
Abnormality of the endocrine system
10%
Abnormality of the genitourinary system
10%
Abnormality of the immune system
10%
Abnormality of the musculoskeletal system
10%
Growth abnormality
10%
Abnormal cellular phenotype
6.7%
Abnormality of the digestive system
6.7%
Abnormality of the ear
6.7%
Abnormality of prenatal development or birth
3.3%
Neoplasm
3.3%
Abnormality of metabolism homeostasis
0%
Abnormality of the breast
0%
Abnormality of the respiratory system
0%
Abnormality of the thoracic cavity
0%
Abnormality of the voice
0%
Constitutional symptom
0%

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