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UniProtKB/Swiss-Prot P17405: Variant p.Gln294Lys

Sphingomyelin phosphodiesterase
Gene: SMPD1
Variant information

Variant position:  294
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 Glutamine (Q) to Lysine (K) at position 294 (Q294K, p.Gln294Lys).
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 medium size and polar (Q) to large size and basic (K)
The physico-chemical property of the reference and variant residues and the change implicated.

BLOSUM score:  1
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:  Niemann-Pick disease A (NPDA) [MIM:257200]: An early-onset lysosomal storage disorder caused by failure to hydrolyze sphingomyelin to ceramide. It results in the accumulation of sphingomyelin and other metabolically related lipids in reticuloendothelial and other cell types throughout the body, leading to cell death. Niemann-Pick disease type A is a primarily neurodegenerative disorder characterized by onset within the first year of life, mental retardation, digestive disorders, failure to thrive, major hepatosplenomegaly, and severe neurologic symptoms. The severe neurological disorders and pulmonary infections lead to an early death, often around the age of four. Clinical features are variable. A phenotypic continuum exists between type A (basic neurovisceral) and type B (purely visceral) forms of Niemann-Pick disease, and the intermediate types encompass a cluster of variants combining clinical features of both types A and B. {ECO:0000269|PubMed:12556236, ECO:0000269|PubMed:1391960, ECO:0000269|PubMed:15221801, ECO:0000269|PubMed:15877209, ECO:0000269|PubMed:1618760, ECO:0000269|PubMed:1718266, ECO:0000269|PubMed:18815062, ECO:0000269|PubMed:19405096, ECO:0000269|PubMed:2023926, ECO:0000269|PubMed:20386867, ECO:0000269|PubMed:22818240, ECO:0000269|PubMed:23252888, ECO:0000269|PubMed:23430884, ECO:0000269|PubMed:26499107, ECO:0000269|PubMed:27338287, ECO:0000269|PubMed:8680412, ECO:0000269|PubMed:8693491, ECO:0000269|PubMed:9266408}. 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 NPDA; strongly reduces enzyme activity; intermediate form with clinical features of both Niemann-Pick disease types A and B.
Any additional useful information about the variant.

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



Sequence information

Variant position:  294
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  631
The length of the canonical sequence.

Location on the sequence:   MVYWTGDIPAHDVWHQTRQD  Q LRALTTVTALVRKFLGPVPV
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                         MVYWTGDIPAHDVWHQTRQDQLRALTTVTALVRKFLGPVPV

Mouse                         MVYWTGDIPAHDVWQQSRQDQLRALTTITDLVRKFLGPVPV

Bovine                        MVYWTGDIPAHNIWQQSRQDQLRALTTITALVKKFLGPVPV

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 47 – 631 Sphingomyelin phosphodiesterase
Metal binding 280 – 280 Zinc 1
Metal binding 280 – 280 Zinc 2
Helix 291 – 309


Literature citations

Two novel mutations in patients with atypical phenotypes of acid sphingomyelinase deficiency.
Pavluu H.; Elleder M.;
J. Inherit. Metab. Dis. 20:615-616(1997)
Cited for: VARIANTS NPDA LYS-294 AND PRO-343;

Acid sphingomyelinase: identification of nine novel mutations among Italian Niemann Pick type B patients and characterization of in vivo functional in-frame start codon.
Pittis M.G.; Ricci V.; Guerci V.I.; Marcais C.; Ciana G.; Dardis A.; Gerin F.; Stroppiano M.; Vanier M.T.; Filocamo M.; Bembi B.;
Hum. Mutat. 24:186-187(2004)
Cited for: VARIANTS NPDB PRO-105; PRO-227; CYS-246; THR-283; LYS-294 AND ILE-384;

Acid sphingomyelinase deficiency. Phenotype variability with prevalence of intermediate phenotype in a series of twenty-five Czech and Slovak patients. A multi-approach study.
Pavluu-Pereira H.; Asfaw B.; Poupctova H.; Ledvinova J.; Sikora J.; Vanier M.T.; Sandhoff K.; Zeman J.; Novotna Z.; Chudoba D.; Elleder M.;
J. Inherit. Metab. Dis. 28:203-227(2005)
Cited for: VARIANTS NPDA ARG-168; LEU-186; HIS-230; VAL-243; ARG-250; GLU-253; ALA-280; HIS-291; LYS-294; PRO-343; HIS-378; TRP-476; ARG-535 AND SER-579; VARIANT ARG-508; CATALYTIC ACTIVITY; CHARACTERIZATION OF VARIANTS NPDA LEU-186; GLU-253; ALA-280; LYS-294; PRO-343 AND HIS-378;

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.