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UniProtKB/Swiss-Prot P35499: Variant p.Phe671Ser

Sodium channel protein type 4 subunit alpha
Gene: SCN4A
Variant information

Variant position:  671
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 Phenylalanine (F) to Serine (S) at position 671 (F671S, p.Phe671Ser).
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 (F) to small size and polar (S)
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

Involvement in disease:  Myotonia SCN4A-related (MYOSCN4A) [MIM:608390]: A phenotypically highly variable myotonia aggravated by potassium loading, and sometimes by cold. Myotonia is characterized by sustained muscle tensing that prevents muscles from relaxing normally. It causes muscle stiffness that can interfere with movement. In some people the stiffness is very mild, while in other cases it may be severe enough to interfere with walking, running, and other activities of daily life. Myotonia SCN4A-related includes myotonia permanens and myotonia fluctuans. In myotonia permanens, the myotonia is generalized and there is a hypertrophy of the muscle, particularly in the neck and the shoulder. Attacks of severe muscle stiffness of the thoracic muscles may be life threatening due to impaired ventilation. In myotonia fluctuans, the muscle stiffness may fluctuate from day to day, provoked by exercise. {ECO:0000269|PubMed:10218481, ECO:0000269|PubMed:16786525, ECO:0000269|PubMed:16832098, ECO:0000269|PubMed:17212350, ECO:0000269|PubMed:17998485, ECO:0000269|PubMed:18203179, ECO:0000269|PubMed:18337100, ECO:0000269|PubMed:19015483, ECO:0000269|PubMed:19347921, ECO:0000269|PubMed:20076800, ECO:0000269|PubMed:27653901, ECO:0000269|PubMed:8058156, ECO:0000269|PubMed:9392583}. 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 MYOSCN4A.
Any additional useful information about the variant.



Sequence information

Variant position:  671
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  1836
The length of the canonical sequence.

Location on the sequence:   TLSLVELGLANVQGLSVLRS  F RLLRVFKLAKSWPTLNMLIK
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                         TLSLVELGLANVQGLSVLRSFRLLRVFKLAKSWPTLNMLIK

Mouse                         TLSLVELGLANVQGLSVLRSFRLLRVFKLAKSWPTLNMLIK

Rat                           TLSLVELGLANVQGLSVLRSFRLLRVFKLAKSWPTLNMLIK

Horse                         TLSWVELGLVNVKGLSVLRSFRLVRSLKLAKSWPTLNMFIR

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 – 1836 Sodium channel protein type 4 subunit alpha
Transmembrane 665 – 682 Helical; Name=S4 of repeat II
Repeat 560 – 832 II


Literature citations

Clinical, electrophysiologic, and genetic study of non-dystrophic myotonia in French-Canadians.
Dupre N.; Chrestian N.; Bouchard J.-P.; Rossignol E.; Brunet D.; Sternberg D.; Brais B.; Mathieu J.; Puymirat J.;
Neuromuscul. Disord. 19:330-334(2009)
Cited for: VARIANTS MYOSCN4A MET-445; LYS-452; SER-671; VAL-1306 AND ILE-1476;

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.