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UniProtKB/Swiss-Prot P06865: Variant p.Trp420Cys

Beta-hexosaminidase subunit alpha
Gene: HEXA
Variant information

Variant position:  420
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Type of variant:  LP/P [Disclaimer]
The variants are classified into three categories: LP/P, LB/B and US.
  • LP/P: likely pathogenic or pathogenic.
  • LB/B: likely benign or benign.
  • US: uncertain significance

Residue change:  From Tryptophan (W) to Cysteine (C) at position 420 (W420C, p.Trp420Cys).
Indicates the amino acid change of the variant. The one-letter and three-letter codes for amino acids used in UniProtKB/Swiss-Prot are those adopted by the commission on Biochemical Nomenclature of the IUPAC-IUB.

Physico-chemical properties:  Change from large size and aromatic (W) to medium size and polar (C)
The physico-chemical property of the reference and variant residues and the change implicated.

BLOSUM score:  -2
The score within a Blosum matrix for the corresponding wild-type to variant amino acid change. The log-odds score measures the logarithm for the ratio of the likelihood of two amino acids appearing by chance. The Blosum62 substitution matrix is used. This substitution matrix contains scores for all possible exchanges of one amino acid with another:
  • Lowest score: -4 (low probability of substitution).
  • Highest score: 11 (high probability of substitution).
More information can be found on the following page

Variant description:  In GM2G1; infantile; inactive protein.
Any additional useful information about the variant.

Other resources:  
Links to websites of interest for the variant.



Sequence information

Variant position:  420
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  529
The length of the canonical sequence.

Location on the sequence:   YMKELELVTKAGFRALLSAP  W YLNRISYGPDWKDFYIVEPL
The residue change on the sequence. Unless the variant is located at the beginning or at the end of the protein sequence, both residues upstream (20) and downstream (20) of the variant will be shown.

Sequence annotation in neighborhood:  
The regions or sites of interest surrounding the variant. In general the features listed are posttranslational modifications, binding sites, enzyme active sites, local secondary structure or other characteristics reported in the cited references. The "Sequence annotation in neighborhood" lines have a fixed format:
  • Type: the type of sequence feature.
  • Positions: endpoints of the sequence feature.
  • Description: contains additional information about the feature.

TypePositionsDescription
Chain 89 – 529 Beta-hexosaminidase subunit alpha
Alternative sequence 361 – 529 Missing. In isoform 2.


Literature citations

A new point mutation in the beta-hexosaminidase alpha subunit gene responsible for infantile Tay-Sachs disease in a non-Jewish Caucasian patient (a Kpn mutant).
Tanaka A.; Punnett H.H.; Suzuki K.;
Am. J. Hum. Genet. 47:568-574(1990)
Cited for: VARIANT GM2G1 CYS-420;

Different attenuated phenotypes of GM2 gangliosidosis variant B in Japanese patients with HEXA mutations at codon 499, and five novel mutations responsible for infantile acute form.
Tanaka A.; Hoang L.T.; Nishi Y.; Maniwa S.; Oka M.; Yamano T.;
J. Hum. Genet. 48:571-574(2003)
Cited for: VARIANTS GM2G1 LEU-252; SER-295; CYS-420; CYS-499 AND HIS-499;

Disclaimer: Any medical or genetic information present in this entry is provided for research, educational and informational purposes only. They are not in any way intended to be used as a substitute for professional medical advice, diagnostic, treatment or care.