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Elevated serum creatine phosphokinase in subjects with McLeod syndrome
Insights
The McLeod phenotype, linked to the Kell blood group, is associated with elevated serum creatine phosphokinase (CPK) levels, indicating a muscle cell anomaly. This finding suggests a pleiotropic effect of the X-linked gene responsible for the McLeod red cell phenotype.
Area of Science:
- Genetics
- Hematology
- Biochemistry
Background:
- McLeod phenotype red cells exhibit acanthocytic morphology and reduced in vivo survival.
- This X-linked phenotype is observed in males with and without X-linked chronic granulomatous disease (CGD).
Purpose of the Study:
- To investigate the association between the McLeod phenotype and serum creatine phosphokinase (CPK) levels.
- To determine if elevated CPK is a consistent finding in individuals with the McLeod phenotype.
Main Methods:
- Serum creatine phosphokinase (CPK) levels were measured in males with the McLeod phenotype.
- Muscle biopsies were performed to assess for muscle cell changes.
- Family studies were conducted on a kindred with multiple McLeod phenotype individuals.
Main Results:
- All 11 males with McLeod syndrome (without CGD) showed elevated serum CPK levels (MM isoenzyme).
- Males with McLeod syndrome and CGD had normal or high CPK levels.
- Individuals with other Kell system variants had normal CPK levels, and elevated CPK was specific to McLeod phenotype members in a large kindred.
Conclusions:
- Elevated serum CPK in McLeod phenotype individuals reflects a muscle cell anomaly.
- This muscle anomaly is a pleiotropic effect of the X-linked gene causing the McLeod red cell phenotype.
Abstract:
McLeod phenotype red cells of the Kell blood group system have acanthocytic morphology and reduced in vivo survival. The phenotype has an X-linked mode of inheritance and is found in some males who have no abnormality of leukocyte function and in some who have X-linked chronic granulomatous disease (CGD). We now describe an association between the McLeod phenotype and an abnormal elevation of serum creatine phosphokinase (CPK). The increase is of the MM isoenzyme type, derived from skeletal muscle or cardiac muscle, and muscle biopsy shows evidence of muscle cell changes. All of 11 males who have McLeod syndrome but do not have CGD have high levels of serum CPK. Males with McLeod syndrome and CGD may have normal or high levels of the enzyme. Individuals with other variant phenotypes in the Kell system have normal levels of serum CPK. Studies on a large kindred, which includes 5 people of McLeod phenotype, show high CPK levels only in the members of McLeod type. We conclude that the high level of CPK in the serum of these people is a reflection of a muscle cell anomaly and that in these individuals it is a pleiotropic effect of the X-linked gene that produces the McLeod red cell phenotype.