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UniProtKB/Swiss-Prot O43526: Variant p.Ala306Thr

Potassium voltage-gated channel subfamily KQT member 2
Gene: KCNQ2
Chromosomal location: 20q13.3
Variant information

Variant position:  306
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Type of variant:  Disease [Disclaimer]
The variants are classified into three categories: Disease, Polymorphism and Unclassified.
  • Disease: Variants implicated in disease according to literature reports.
  • Polymorphism: Variants not reported to be implicated in disease.
  • Unclassified: Variants with uncertain implication in disease according to literature reports. Evidence against or in favor of a pathogenic role is limited and/or conflicting.

Residue change:  From Alanine (A) to Threonine (T) at position 306 (A306T, p.Ala306Thr).
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 small size and hydrophobic (A) to medium size and polar (T)
The physico-chemical property of the reference and variant residues and the change implicated.

BLOSUM score:  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

Involvement in disease:  Epileptic encephalopathy, early infantile, 7 (EIEE7) [MIM:613720]: An autosomal dominant seizure disorder characterized by infantile onset of refractory seizures with resultant delayed neurologic development and persistent neurologic abnormalities. {ECO:0000269|PubMed:12742592, ECO:0000269|PubMed:15249611, ECO:0000269|PubMed:24463883, ECO:0000269|PubMed:25740509, ECO:0000269|PubMed:25818041, ECO:0000269|PubMed:26138355, ECO:0000269|PubMed:26993267, ECO:0000269|PubMed:27864847}. Note=The disease is caused by mutations affecting the gene represented in this entry.
The name and a short description of the disease associated with the variant. For more information about the disease, the user can refer to OMIM, following the link provided after the disease acronym.

Involvement in disease:  Seizures, benign familial neonatal 1 (BFNS1) [MIM:121200]: A disorder characterized by clusters of seizures occurring in the first days of life. Most patients have spontaneous remission by 12 months of age and show normal psychomotor development. Some rare cases manifest an atypical severe phenotype associated with epileptic encephalopathy and psychomotor retardation. The disorder is distinguished from benign familial infantile seizures by an earlier age at onset. In some patients, neonatal convulsions are followed later in life by myokymia, a benign condition characterized by spontaneous involuntary contractions of skeletal muscles fiber groups that can be observed as vermiform movement of the overlying skin. Electromyography typically shows continuous motor unit activity with spontaneous oligo- and multiplet-discharges of high intraburst frequency (myokymic discharges). Some patients may have isolated myokymia. {ECO:0000269|PubMed:11175290, ECO:0000269|PubMed:11572947, ECO:0000269|PubMed:14534157, ECO:0000269|PubMed:15249611, ECO:0000269|PubMed:23360469, ECO:0000269|PubMed:25982755, ECO:0000269|PubMed:26993267, ECO:0000269|PubMed:9425895}. Note=The disease is caused by mutations affecting the gene represented in this entry.
The name and a short description of the disease associated with the variant. For more information about the disease, the user can refer to OMIM, following the link provided after the disease acronym.

Variant description:  In BFNS1 and EIEE7; 20%-40% reduction of wt current in heteromeric channels.
Any additional useful information about the variant.

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



Sequence information

Variant position:  306
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  872
The length of the canonical sequence.

Location on the sequence:   QTWNGRLLAATFTLIGVSFF  A LPAGILGSGFALKVQEQHRQ
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: 
The multiple alignment of the region surrounding the variant against various orthologous sequences.

Human                         QTWNGRLLAATFTLIGVSFFALPAGILGSGFALKVQEQHRQ

Mouse                         QTWNGRLLAATFTLIGVSFFALPAGILGSGFALKVQEQHRP

Rat                           QTWNGRLLAATFTLIGVSFFALPAGILGSGFALKVQEQHRQ

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 1 – 872 Potassium voltage-gated channel subfamily KQT member 2
Transmembrane 292 – 312 Helical; Name=Segment S6


Literature citations

A novel potassium channel gene, KCNQ2, is mutated in an inherited epilepsy of newborns.
Singh N.A.; Charlier C.; Stauffer D.; DuPont B.R.; Leach R.J.; Melis R.; Ronen G.M.; Bjerre I.; Quattlebaum T.; Murphy J.V.; McHarg M.L.; Gagnon D.; Rosales T.O.; Peiffer A.; Anderson V.E.; Leppert M.;
Nat. Genet. 18:25-29(1998)
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1); VARIANTS BFNS1 CYS-284 AND THR-306;

Moderate loss of function of cyclic-AMP-modulated KCNQ2/KCNQ3 K+ channels causes epilepsy.
Schroeder B.C.; Kubisch C.; Stein V.; Jentsch T.J.;
Nature 396:687-690(1998)
Cited for: MUTAGENESIS OF SER-52 AND GLY-279; PHOSPHORYLATION AT SER-52; CHARACTERIZATION OF VARIANTS CYS-284 AND THR-306;

KCNQ2 and KCNQ3 potassium channel genes in benign familial neonatal convulsions: expansion of the functional and mutation spectrum.
Singh N.A.; Westenskow P.; Charlier C.; Pappas C.; Leslie J.; Dillon J.; Anderson V.E.; Sanguinetti M.C.; Leppert M.F.;
Brain 126:2726-2737(2003)
Cited for: VARIANTS BFNS1 VAL-208; GLN-228; PHE-243; CYS-284; THR-306 AND GLN-333; CHARACTERIZATION OF VARIANTS BFNS1 VAL-208 AND GLN-333; FUNCTION;

Whole-exome sequencing improves the diagnosis yield in sporadic infantile spasm syndrome.
Dimassi S.; Labalme A.; Ville D.; Calender A.; Mignot C.; Boutry-Kryza N.; de Bellescize J.; Rivier-Ringenbach C.; Bourel-Ponchel E.; Cheillan D.; Simonet T.; Maincent K.; Rossi M.; Till M.; Mougou-Zerelli S.; Edery P.; Saad A.; Heron D.; des Portes V.; Sanlaville D.; Lesca G.;
Clin. Genet. 89:198-204(2016)
Cited for: VARIANT EIEE7 THR-306;

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.