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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot P08397: Variant p.Arg26His

Porphobilinogen deaminase
Gene: HMBS
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Variant information Variant position: help 26 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 Arginine (R) to Histidine (H) at position 26 (R26H, p.Arg26His). 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 basic (R) to medium size and polar (H) The physico-chemical property of the reference and variant residues and the change implicated.
BLOSUM score: help 0 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 AIP; severely decreased in hydroxymethylbilane synthase activity. Any additional useful information about the variant.
Other resources: help Links to websites of interest for the variant.


Sequence information Variant position: help 26 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 361 The length of the canonical sequence.
Location on the sequence: help NAAATAEENSPKMRVIRVGT R KSQLARIQTDSVVATLKASY 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.
Residue conservation: help The multiple alignment of the region surrounding the variant against various orthologous sequences. 
Human                         NAAATAEENSPKMRVIRVGTRKSQLARIQTDSVVATLKASY

Mouse                         GAATTAEENGSKMRVIRVGTRKSQLARIQTDTVVAMLKALY

Rat                           GAATTAEENGSMMRVIRVGTRKSQLARIQTDTVVAMLKTLY

Bovine                        NAAAIAEEDTPKMRVIRVGTRKSQLARIQTDSVVATLKALY

Slime mold                    ------MSSITKRDKVIIGSRKSQLAMLQTEWVRDRIQELN

Baker's yeast                 --------MGPE--TLHIGGRKSKLAVIQSNHVLKLIEEKY

Fission yeast                 ---------MPSCTSFPIGTRKSKLAVIQSEIIREELEKHY
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 2 – 361 Porphobilinogen deaminase
Modified residue 15 – 15 Phosphoserine
Mutagenesis 26 – 26 R -> A. Loss of hydroxymethylbilane synthase activity.
Mutagenesis 34 – 34 Q -> A. Loss of hydroxymethylbilane synthase activity.



Literature citations
Acute intermittent porphyria caused by an arginine to histidine substitution (R26H) in the cofactor-binding cleft of porphobilinogen deaminase.
Llewellyn D.H.; Whatley S.D.; Elder G.H.;
Hum. Mol. Genet. 2:1315-1316(1993)
Cited for: VARIANT AIP HIS-26; Comparison of complementary and genomic DNA sequencing for the detection of mutations in the HMBS gene in British patients with acute intermittent porphyria: identification of 25 novel mutations.
Whatley S.D.; Woolf J.R.; Elder G.H.;
Hum. Genet. 104:505-510(1999)
Cited for: VARIANTS AIP CYS-22; CYS-26; HIS-26; PRO-31; SER-42; ASN-61; ARG-85; GLY-90; ARG-111; GLN-173; TRP-173; ARG-177; CYS-195; ASP-219; ARG-247 AND ILE-269; Acute intermittent porphyria in Sweden. Molecular, functional and clinical consequences of some new mutations found in the porphobilinogen deaminase gene.
Floderus Y.; Shoolingin-Jordan P.M.; Harper P.;
Clin. Genet. 62:288-297(2002)
Cited for: VARIANTS AIP CYS-26; HIS-26; VAL-86; PRO-92; GLY-99; ARG-111; THR-113; GLN-173; ASN-178; GLN-225; GLY-225; TYR-256; ASP-260 AND PRO-343; Molecular study of the hydroxymethylbilane synthase gene (HMBS) among Polish patients with acute intermittent porphyria.
Gregor A.; Schneider-Yin X.; Szlendak U.; Wettstein A.; Lipniacka A.; Ruefenacht U.B.; Minder E.I.;
Hum. Mutat. 19:310-310(2002)
Cited for: VARIANTS AIP HIS-26; TYR-61; VAL-93 DEL; ARG-111; GLN-173 AND ASP-335; Nine mutations including three novel mutations among Russian patients with acute intermittent porphyria.
Pischik E.; Mehtaelae S.; Kauppinen R.;
Hum. Mutat. 26:496-496(2005)
Cited for: VARIANTS AIP HIS-26; TRP-173; CYS-195; ARG-247 AND ALA-250; CHARACTERIZATION OF VARIANTS AIP HIS-26; TRP-173; CYS-195; ARG-247 AND ALA-250; Acute intermittent porphyria--impact of mutations found in the hydroxymethylbilane synthase gene on biochemical and enzymatic protein properties.
Ulbrichova D.; Hrdinka M.; Saudek V.; Martasek P.;
FEBS J. 276:2106-2115(2009)
Cited for: VARIANTS AIP CYS-26; HIS-26; GLN-173; LYS-204 AND ASP-250; CHARACTERIZATION OF VARIANTS AIP CYS-26; HIS-26; GLN-173; LYS-204 AND ASP-250; From a dominant to an oligogenic model of inheritance with environmental modifiers in acute intermittent porphyria.
Lenglet H.; Schmitt C.; Grange T.; Manceau H.; Karboul N.; Bouchet-Crivat F.; Robreau A.M.; Nicolas G.; Lamoril J.; Simonin S.; Mirmiran A.; Karim Z.; Casalino E.; Deybach J.C.; Puy H.; Peoc'h K.; Gouya L.;
Hum. Mol. Genet. 27:1164-1173(2018)
Cited for: VARIANTS AIP PHE-30 AND GLU-235; CHARACTERIZATION OF VARIANTS AIP SER-24; CYS-26; HIS-26; ASN-28; PHE-30; MET-35; PHE-96; ARG-111; TRP-116; ASP-124; GLN-149; LEU-149; HIS-217; GLU-235; ARG-247; ALA-250; GLN-250; VAL-250; TYR-256 AND MET-267;
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.