- Email: [email protected]
Serum pyruvate kinase in carriers of duchenne muscular dystrophy
Journal of the Neurological Sciences, 1977, 32: 137-139
137
© Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
Short Report
S E R U M P Y R U V A T E K I N A S E I N C A R R I E R S OF D U C H E N N E M U S C U L A R DYSTROPHY
M. F. HARDY, D. GARDNER-MEDWIN and R. J. T. PENNINGTON
Regional Neurological Centre, General Hospital, Newcastle upon Tyne (Great Britain)
(Received 23 December, 1976)
SUMMARY Five out of 17 carriers of the gene for Duchenne muscular dystrophy had an increased level of serum pyruvate kinase activity, whilst 11, including the same 5, showed an increase in serum creatine kinase.
INTRODUCTION Duchenne muscular dystrophy is characterized by the leakage of many muscle enzymes into the blood, and female carriers of this X-linked recessive disease also often show an elevated level of some enzymes in the blood plasma. It has been generally accepted that creatine kinase (CK) is the most consistently elevated plasma enzyme in carriers, and is the one normally used for carrier detection. Most workers have found an increased level of serum C K in about 2 out of 3 carriers. However, Alberts and Samaha (1974) reported that the serum level of another enzyme, pyruvate kinase (PK) was elevated in a higher proportion of carriers than was CK. Harano, Adair, Vignos, Miller and Kowal (1973) had previously found very high elevations of this enzyme in Duchenne patients. We have now carried out serum P K and C K measurements on a series of carriers to see whether the findings of Alberts and Samaha (1974) could be supported. MATERIALS AND METHODS Serum was obtained from 17 definite carriers of the gene for Duchenne dystrophy (defined using the criteria of Gardner-Medwin, Pennington and Walton 1971). Controls were normal adult female volunteers. Serum was separated within 2 hr of sampling This work was supported by the Medical Research Council and the Muscular Dystrophy Group of Great Britain.
138 and frozen at - - 2 0 °C. C K was measured within 2 weeks. Measurement o f PK was carried out within 10 months of storage. Muscle type PK is stable for at least I year in frozen stored serum ( H a r a n o et al. 1973) and we found no change in the ratio of activity with 0.2 m M and 2 m M phosphoenolpyruvate (PEP) concentration on storage, thus indicating that there is no loss of liver type PK. PK was measured at 37 °C using the procedure of H a r a n o et al. (1973); the thawed samples were incubated at 25 °C for 30 rain before assaying. C K was measured at 37 °C as previously described (Pearce, Pennington and W a l t o n 1964), based on the colorimetric determination of the creatine formed in the enzyme reaction. RESULTS AND DISCUSSION The serum P K on 21 normal subjects ranged f r o m 10.0 to 72.7 #mol/min/I (mean 30.6). The distribution o f the values was skewed but the logarithms showed a n o r m a l distribution about the mean. The normal range, based on mean i 2 SD o f logarithms o f the P K levels, was 11.0-69.3. Serum C K (40 normal subjects) was 7.5-66.6/~mol/min/1 (mean 27.2). Neither the C K values nor the logarithms o f these showed a normal distribution. The normal upper limit (97.5 ~ confidence level) was TABLE 1 SERUM PK AND CK LEVELS IN CARRIERS OF DUCHENNE MUSCULAR DYSTROPHY Age of carriers (years)
Enzyme activity (#mol/min/1) PK
CK
21 27 28 29 30 30 32 35 36 42 42 43 46 47 48 51 66
18.2 61.7 61.3 168 221 17.8 38.0 76.2 73.7 57.3 15.0 4.5 6.0 28.2 57.5 108 11.3
57.9 76.9 222 510 691 32.9 125 121 598 289 49.6 33.9 240 52.7 182 694 39.8
Mean
69.2
Upper normal limit (see text)
69.3
236 65.0
139 o b t a i n e d therefore f r o m a c u m u l a t i v e frequency plot (Griffiths 1966), a n d was f o u n d to be 65.0. Table 1 shows the P K a n d C K results o b t a i n e d on the individual carriers. The m e a n elevation o f s e r u m P K is very m u c h less t h a n t h a t o f C K , a n d only 5 o u t o f the 17 carriers had a P K value a b o v e the n o r m a l range. Eleven out o f 17 carriers h a d elevated C K activity. N o n e o f the subjects with n o r m a l C K h a d an a b n o r m a l P K . O u r results therefore differ c o n s i d e r a b l y f r o m those o f A l b e r t s and S a m a h a (1974) a n d indicate t h a t P K is a less sensitive index t h a n C K o f the c a r r i e r state. The o b s e r v a t i o n by these w o r k e r s t h a t some carriers have raised P K but n o r m a l C K clearly merits further investigation since, if confirmed, it w o u l d be w o r t h while c a r r y i n g out measurements o f b o t h enzymes on suspected carriers. It is w o r t h noting, however, t h a t the p r o p o r t i o n o f raised C K s in m y o p a t h i c patients a n d D u c h e n n e carriers r e p o r t e d by A l b e r t s a n d S a m a h a (1974) was lower t h a n is usually found. T h e r e was a significant (P < 0.01) c o r r e l a t i o n between the levels o f the two enzymes in the carriers. ACKNOWLEDGEMENTS Mr. K. D a v i s o n a n d Mrs. K. B r o w n p r o v i d e d technical assistance.
REFERENCES Alberts, M. C. and F. J. Samaha (1974) Serum pyruvate kinase in muscle diseases and carrier states, Neurology ( Minneap. ) , 24: 462-464. Gardner-Medwin, D., R. J. Pennington and J. N. Walton (1971) The detection of carriers of X-linked muscular dystrophy genes - - A review of some methods studied in Newcastle upon Tyne, J. neurol. Sci., 13 : 459-474. Griffiths, P. D. (1966) Serum levels of ATP:creatine phosphotransferase (creatine kinase) - - The normal range and effect of muscular activity, Clin. chim. Acta, 13: 413-420. Harano, Y., R. Adair, P. J. Vignos, Jr., M. Miller and J. Kowal (1973) Pyruvate kinase isoenzymes in progressive muscular dystrophy and in acute myocardial infarction, Metabolism, 22: 493-501. Pearce, J. M. S., R. J. Pennington and J. N. Walton (1964) Serum enzyme studies in muscle disease, Part 1 (Variations in serum creatine kinase activity in normal individuals), J. NeuroL Neurosurg. Psychiat., 27 : 1-4.
137
© Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
Short Report
S E R U M P Y R U V A T E K I N A S E I N C A R R I E R S OF D U C H E N N E M U S C U L A R DYSTROPHY
M. F. HARDY, D. GARDNER-MEDWIN and R. J. T. PENNINGTON
Regional Neurological Centre, General Hospital, Newcastle upon Tyne (Great Britain)
(Received 23 December, 1976)
SUMMARY Five out of 17 carriers of the gene for Duchenne muscular dystrophy had an increased level of serum pyruvate kinase activity, whilst 11, including the same 5, showed an increase in serum creatine kinase.
INTRODUCTION Duchenne muscular dystrophy is characterized by the leakage of many muscle enzymes into the blood, and female carriers of this X-linked recessive disease also often show an elevated level of some enzymes in the blood plasma. It has been generally accepted that creatine kinase (CK) is the most consistently elevated plasma enzyme in carriers, and is the one normally used for carrier detection. Most workers have found an increased level of serum C K in about 2 out of 3 carriers. However, Alberts and Samaha (1974) reported that the serum level of another enzyme, pyruvate kinase (PK) was elevated in a higher proportion of carriers than was CK. Harano, Adair, Vignos, Miller and Kowal (1973) had previously found very high elevations of this enzyme in Duchenne patients. We have now carried out serum P K and C K measurements on a series of carriers to see whether the findings of Alberts and Samaha (1974) could be supported. MATERIALS AND METHODS Serum was obtained from 17 definite carriers of the gene for Duchenne dystrophy (defined using the criteria of Gardner-Medwin, Pennington and Walton 1971). Controls were normal adult female volunteers. Serum was separated within 2 hr of sampling This work was supported by the Medical Research Council and the Muscular Dystrophy Group of Great Britain.
138 and frozen at - - 2 0 °C. C K was measured within 2 weeks. Measurement o f PK was carried out within 10 months of storage. Muscle type PK is stable for at least I year in frozen stored serum ( H a r a n o et al. 1973) and we found no change in the ratio of activity with 0.2 m M and 2 m M phosphoenolpyruvate (PEP) concentration on storage, thus indicating that there is no loss of liver type PK. PK was measured at 37 °C using the procedure of H a r a n o et al. (1973); the thawed samples were incubated at 25 °C for 30 rain before assaying. C K was measured at 37 °C as previously described (Pearce, Pennington and W a l t o n 1964), based on the colorimetric determination of the creatine formed in the enzyme reaction. RESULTS AND DISCUSSION The serum P K on 21 normal subjects ranged f r o m 10.0 to 72.7 #mol/min/I (mean 30.6). The distribution o f the values was skewed but the logarithms showed a n o r m a l distribution about the mean. The normal range, based on mean i 2 SD o f logarithms o f the P K levels, was 11.0-69.3. Serum C K (40 normal subjects) was 7.5-66.6/~mol/min/1 (mean 27.2). Neither the C K values nor the logarithms o f these showed a normal distribution. The normal upper limit (97.5 ~ confidence level) was TABLE 1 SERUM PK AND CK LEVELS IN CARRIERS OF DUCHENNE MUSCULAR DYSTROPHY Age of carriers (years)
Enzyme activity (#mol/min/1) PK
CK
21 27 28 29 30 30 32 35 36 42 42 43 46 47 48 51 66
18.2 61.7 61.3 168 221 17.8 38.0 76.2 73.7 57.3 15.0 4.5 6.0 28.2 57.5 108 11.3
57.9 76.9 222 510 691 32.9 125 121 598 289 49.6 33.9 240 52.7 182 694 39.8
Mean
69.2
Upper normal limit (see text)
69.3
236 65.0
139 o b t a i n e d therefore f r o m a c u m u l a t i v e frequency plot (Griffiths 1966), a n d was f o u n d to be 65.0. Table 1 shows the P K a n d C K results o b t a i n e d on the individual carriers. The m e a n elevation o f s e r u m P K is very m u c h less t h a n t h a t o f C K , a n d only 5 o u t o f the 17 carriers had a P K value a b o v e the n o r m a l range. Eleven out o f 17 carriers h a d elevated C K activity. N o n e o f the subjects with n o r m a l C K h a d an a b n o r m a l P K . O u r results therefore differ c o n s i d e r a b l y f r o m those o f A l b e r t s and S a m a h a (1974) a n d indicate t h a t P K is a less sensitive index t h a n C K o f the c a r r i e r state. The o b s e r v a t i o n by these w o r k e r s t h a t some carriers have raised P K but n o r m a l C K clearly merits further investigation since, if confirmed, it w o u l d be w o r t h while c a r r y i n g out measurements o f b o t h enzymes on suspected carriers. It is w o r t h noting, however, t h a t the p r o p o r t i o n o f raised C K s in m y o p a t h i c patients a n d D u c h e n n e carriers r e p o r t e d by A l b e r t s a n d S a m a h a (1974) was lower t h a n is usually found. T h e r e was a significant (P < 0.01) c o r r e l a t i o n between the levels o f the two enzymes in the carriers. ACKNOWLEDGEMENTS Mr. K. D a v i s o n a n d Mrs. K. B r o w n p r o v i d e d technical assistance.
REFERENCES Alberts, M. C. and F. J. Samaha (1974) Serum pyruvate kinase in muscle diseases and carrier states, Neurology ( Minneap. ) , 24: 462-464. Gardner-Medwin, D., R. J. Pennington and J. N. Walton (1971) The detection of carriers of X-linked muscular dystrophy genes - - A review of some methods studied in Newcastle upon Tyne, J. neurol. Sci., 13 : 459-474. Griffiths, P. D. (1966) Serum levels of ATP:creatine phosphotransferase (creatine kinase) - - The normal range and effect of muscular activity, Clin. chim. Acta, 13: 413-420. Harano, Y., R. Adair, P. J. Vignos, Jr., M. Miller and J. Kowal (1973) Pyruvate kinase isoenzymes in progressive muscular dystrophy and in acute myocardial infarction, Metabolism, 22: 493-501. Pearce, J. M. S., R. J. Pennington and J. N. Walton (1964) Serum enzyme studies in muscle disease, Part 1 (Variations in serum creatine kinase activity in normal individuals), J. NeuroL Neurosurg. Psychiat., 27 : 1-4.