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UniProtKB/Swiss-Prot P17405: Variant p.Leu343Pro

Sphingomyelin phosphodiesterase
Gene: SMPD1
Variant information

Variant position:  343
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Type of variant:  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:  From Leucine (L) to Proline (P) at position 343 (L343P, p.Leu343Pro).
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:  Similar physico-chemical property. Both residues are medium size and hydrophobic.
The physico-chemical property of the reference and variant residues and the change implicated.

BLOSUM score:  -3
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:  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.



Sequence information

Variant position:  343
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:   STPVNSFPPPFIEGNHSSRW  L YEAMAKAWEPWLPAEALRTL
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                         STPVNSFPPPFIEGNHSSRWLYEAMAKAWEPWLPAEALRTL

Mouse                         STPVNGFPPPFIKGNQSSQWLYEAMAKAWEPWLPADALHTL

Bovine                        STPVNGFPPPFIKGNQSSHWLYEAMAEAWEPWLPAEALRTL

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
Glycosylation 337 – 337 N-linked (GlcNAc...) asparagine
Mutagenesis 337 – 337 N -> G. No effect on sphingomyelin phosphodiesterase activity. No effect on secretion.
Helix 341 – 350


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 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.