This page is short by design. MV1 has no separate phenotype description in the sources read here, and the substantive evidence sits on MM1, which this page adds to rather than duplicates.
Why is MV1 classified with MM1?
In the 300-case classification series, the classic CJD phenotype was defined by PrPSc type 1 together with at least one methionine allele at codon 129, which covers both MM and MV heterozygous patients. That group accounted for 70 percent of cases, and the series did not separate a distinct MV1 phenotype within it. Later series continue to report MM1 and MV1 together for the same reason.
What is specific to the heterozygous state?
Two observations from the mixed-type study apply to MV patients rather than to MM patients.
First, concurrence of PrPSc types 1 and 2 was detected in 35 percent of 225 cases overall and was higher in methionine homozygotes than in MV or VV subjects, so a given MV1 case is somewhat less likely than an MM1 case to carry coexisting type 2 pathology. Second, in MV cases type 1 accumulation and its related pathology predominated, as in MM cases, while the method best able to detect concurrence differed: neuropathological examination identified mixed features in MM cases and most MV cases, whereas molecular typing was better in MV cases with kuru plaques. Those kuru plaque cases are the MV2K subtype, covered at MV2.
The practical point for a case report or a cohort is that an MV patient with type 1 protein belongs with the classic phenotype, and that calling such a case MV1 says nothing about course or assay performance beyond what MM1 data already say.
Related: subtypes hub, codon 129.
Sources for this page
- Parchi P and others (1999) Classification of sporadic Creutzfeldt-Jakob disease based on molecular and phenotypic analysis of 300 subjects, Ann Neurol 46(2):224-233
- Parchi P and others (2009) Incidence and spectrum of sporadic Creutzfeldt-Jakob disease variants with mixed phenotype and co-occurrence of PrPSc types: an updated classification, Acta Neuropathol 118(5):659-671