NM_004531.4(MOCS2):c.502G>A (p.Glu168Lys) AND Molybdenum cofactor deficiency, complementation group B

Clinical significance:Pathogenic (Last evaluated: Jul 11, 2003)

Review status:(0/4) 0 stars out of maximum of 4 stars

no assertion criteria provided

Based on:
1 submission [Details]
Record status:

Allele description [Variation Report for NM_004531.4(MOCS2):c.502G>A (p.Glu168Lys)]

NM_004531.4(MOCS2):c.502G>A (p.Glu168Lys)

MOCS2:molybdenum cofactor synthesis 2 [Gene - OMIM - HGNC]
Variant type:
single nucleotide variant
Cytogenetic location:
Genomic location:
Preferred name:
NM_004531.4(MOCS2):c.502G>A (p.Glu168Lys)
  • NC_000005.10:g.53098667C>T
  • NG_008435.2:g.16102G>A
  • NM_004531.4:c.502G>A
  • NM_176806.3:c.*422G>A
  • NP_004522.1:p.Glu168Lys
  • NC_000005.9:g.52394497C>T
  • NG_008435.1:g.16102G>A
  • NM_004531.3:c.502G>A
  • NM_176806.2:c.*422G>A
  • O96007:p.Glu168Lys
Protein change:
E168K; GLU168LYS
UniProtKB: O96007#VAR_012765; OMIM: 603708.0002; dbSNP: rs121908605
NCBI 1000 Genomes Browser:
Molecular consequence:
  • NM_176806.3:c.*422G>A - 3 prime UTR variant - [Sequence Ontology: SO:0001624]
  • NM_004531.4:c.502G>A - missense variant - [Sequence Ontology: SO:0001583]


Molybdenum cofactor deficiency, complementation group B (MOCODB)
MedGen: C1854989; Orphanet: 833; OMIM: 252160

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Assertion and evidence details

Submission AccessionSubmitterReview Status
(Assertion method)
Clinical Significance
(Last evaluated)
SCV000026666OMIMno assertion criteria providedPathogenic
(Jul 11, 2003)
germlineliterature only

PubMed (3)
[See all records that cite these PMIDs]

Summary from all submissions

EthnicityOriginAffectedIndividualsFamiliesChromosomes testedNumber TestedFamily historyMethod
not providedgermlinenot providednot providednot providednot providednot providednot providedliterature only



Human molybdopterin synthase gene: genomic structure and mutations in molybdenum cofactor deficiency type B.

Reiss J, Dorche C, Stallmeyer B, Mendel RR, Cohen N, Zabot MT.

Am J Hum Genet. 1999 Mar;64(3):706-11.

PubMed [citation]

The mutational spectrum of single base-pair substitutions in mRNA splice junctions of human genes: causes and consequences.

Krawczak M, Reiss J, Cooper DN.

Hum Genet. 1992 Sep-Oct;90(1-2):41-54.

PubMed [citation]
See all PubMed Citations (3)

Details of each submission

From OMIM, SCV000026666.4

#EthnicityIndividualsChromosomes TestedFamily HistoryMethodCitations
1not providednot providednot providednot providedliterature only PubMed (3)


In a German patient with molybdenum cofactor deficiency of complementation group B (MOCODB; 252160), Reiss et al. (1999) found compound heterozygosity for a 726del2 mutation on the paternal allele and a missense mutation, glu168 to lys (E168K), on the maternal chromosome. The mutation affected the first nucleotide of exon 7 (GAA to AAA). E168 is one of the few extremely conserved residues in the large subunit of molybdopterin synthase and the amino acid substitution E168K was most likely sufficient for impairment of the protein's enzymatic activity. The substituted G, however, contributes to the consensus value of the splice site (Krawczak et al., 1992) and an additional effect on splicing efficiency is possible.

Leimkuhler et al. (2003) found that MOCS2B with the E168K mutation readily formed MPT synthase tetramers with MOCS2A. However, compared with the wildtype enzyme, only a small amount of precursor Z bound tetramers including MOCS2B-E168K, resulting in reduced MPT synthase activity.

OriginAffectedNumber testedTissuePurposeMethodIndividualsAllele frequencyFamiliesCo-occurrences
1germlinenot providednot providednot providednot providednot providednot providednot providednot provided

Last Updated: Jul 21, 2018