• 30
    Haplo
    Score
  • 0
    Triplo
    Score

Gene Facts External Data Attribution

HGNC Symbol
CBS (HGNC:1550) HGNC Entrez Ensembl OMIM UCSC Uniprot GeneReviews LOVD LSDB ClinVar
HGNC Name
cystathionine beta-synthase
Gene type
protein-coding gene
Locus type
gene with protein product
Previous symbols
No previous names found
Alias symbols
HIP4
%HI
40.28(Read more about the DECIPHER Haploinsufficiency Index)
pLI
0(Read more about gnomAD pLI score)
LOEUF
0.73(Read more about gnomAD LOEUF score)
Cytoband
21q22.3
Genomic Coordinates
GRCh37/hg19: chr21:44473301-44496983 NCBI Ensembl UCSC
GRCh38/hg38: chr21:43053191-43076873 NCBI Ensembl UCSC
MANE Select Transcript
NM_000071.3 ENST00000398165.8 (Read more about MANE Select)
Function
Hydro-lyase catalyzing the first step of the transsulfuration pathway, where the hydroxyl group of L-serine is displaced by L- homocysteine in a beta-replacement reaction to form L-cystathionine, the precursor of L-cysteine. This catabolic route allows the elimination of L-methionine and the toxic metabolite L-homocysteine (PubMed:23981774, PubMed:20506325, PubMed:23974653). Also involved in the production of hydrogen sulfide, a gasotransmitter with signaling and cytoprotective effects on neuron... (Source: Uniprot)

Dosage Sensitivity Summary (Gene)

Dosage ID:
ISCA-2866
Curation Status:
Complete
Issue Type:
Dosage Curation - Gene
Haploinsufficiency:
Gene Associated with Autosomal Recessive Phenotype (30)
Triplosensitivity:
No Evidence for Triplosensitivity (0)
Last Evaluated:
08/22/2016

Haploinsufficiency (HI) Score Details

HI Score:
30
HI Evidence Strength:
Gene Associated with Autosomal Recessive Phenotype (Disclaimer)
HI Disease:

Triplosensitivity (TS) Score Details

TS Score:
0
TS Evidence Strength:
No Evidence for Triplosensitivity (Disclaimer)
TS Published Evidence:
  • PUBMED: 11391481
    The CBS gene on chromosome 21 is overexpressed in patients with trisomy 21. This paper (Pogribna et al., 2001; PMID: 11391481) evaluated the impact of overexpression of the CBS gene on homocysteine metabolism in children with DS and to determine whether the supplementation of trisomy 21 lymphoblasts in vitro with selected nutrients would shift the genetically induced metabolic imbalance. They found that plasma levels of cystathionine and cysteine were significantly increased in children with DS, consistent with an increase in CBS activity. The increased activity of CBS in Down syndrome significantly alters homocysteine metabolism so that the folate-dependent resynthesis of methionine is compromised. The decreased availability of homocysteine promotes the well-established 'folate trap,' creating a functional folate deficiency that may contribute to the metabolic pathology of this complex genetic disorder.

Genomic View

Select assembly: (NC_000021.8) (NC_000021.9)