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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot P22557: Variant p.Tyr199His

5-aminolevulinate synthase, erythroid-specific, mitochondrial
Gene: ALAS2
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Variant information Variant position: help 199 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Type of variant: help 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: help From Tyrosine (Y) to Histidine (H) at position 199 (Y199H, p.Tyr199His). 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: help Change from large size and aromatic (Y) to medium size and polar (H) The physico-chemical property of the reference and variant residues and the change implicated.
BLOSUM score: help 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: help In SIDBA1. Any additional useful information about the variant.
Other resources: help Links to websites of interest for the variant.


Sequence information Variant position: help 199 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 587 The length of the canonical sequence.
Location on the sequence: help QHFSEASVASKDVSVWCSND Y LGMSRHPQVLQATQETLQRH 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: help 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 50 – 587 5-aminolevulinate synthase, erythroid-specific, mitochondrial



Literature citations
Four new mutations in the erythroid-specific 5-aminolevulinate synthase (ALAS2) gene causing X-linked sideroblastic anemia: increased pyridoxine responsiveness after removal of iron overload by phlebotomy and coinheritance of hereditary hemochromatosis.
Cotter P.D.; May A.; Li L.; Al-Sabah A.I.; Fitzsimons E.J.; Cazzola M.; Bishop D.F.;
Blood 93:1757-1769(1999)
Cited for: VARIANTS SIDBA1 HIS-199; CYS-411; GLN-448 AND CYS-452;
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.