|Year : 2021 | Volume
| Issue : 3 | Page : 175-181
Serum creatine kinase and other profile of duchenne muscular dystrophy and becker muscular dystrophy: A cross-sectional survey in a tertiary care institution at Kolkata
Santa Saha1, Anindita Joardar2, Sarnava Roy2, Tanushree Mondal3, Gautam Gangopadhyay4, Dibakar Haldar5, Harendra Nath Das6
1 Department of Biochemistry, RIO, Medical College, Kolkata, West Bengal, India
2 Department of Neurology, Neurogenetics Unit, BIN, Kolkata, West Bengal, India
3 Department of Community Medicine, Medical College, Kolkata, West Bengal, India
4 Department of Neurology, BIN, Kolkata, West Bengal, India
5 Department of Community Medicine, B S Medical College, Bankura, West Bengal, India
6 Department of Biochemistry, MGM Medical College, Kishangunj, Bihar, India
|Date of Submission||28-Feb-2020|
|Date of Decision||07-Sep-2020|
|Date of Acceptance||05-Jul-2021|
|Date of Web Publication||04-Mar-2022|
Bidyadhari Housing Cooperative Society, CC-7, Flat No. 503, Newtown, Narkelbagan More, Near Biswabangla Gate, Kolkata - 700 156, West Bengal
Source of Support: None, Conflict of Interest: None
Background: Serum creatine kinase (CK) level is increased muscular dystrophy (MD) and may be used as a clue to identify MDs. Objective: The objective is to compare CK levels between Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), to correlate value of serum CK with number of deletions, duration of illness and to establish a cut off value of CK for screening. Materials and Methods: A cross-sectional survey was carried out in a tertiary care institute of Kolkata. Clinically diagnosed patients of 139 DMDs and 50 BMDs along with 69 age-matched individuals suffering from diseases other than MDs was included. Estimation of serum CK levels and gene analysis were done for all. Results: DMD victims were found to be younger with low age of onset and lesser disease duration but higher serum CK level compared to those having BMD. Most of the genetic deletions were happened in distal region of dystrophin gene and a significant difference was revealed to exist between DMD and BMD neither in regard to proportion of overall deletion nor deletions in proximal and distal region. However, gene deletion was found absent in 31% and 42% of DMD and BMD cases. Serum CK level of 511.5 unit/L was seemed to be a reliable cut-off for detection of DMD and BMD with 97.3% sensitivity, 100% specificity, and area under the curve 0.989 with a P = 0.000. Conclusion: In case of nonavailability of genetic test facility as well as negative genetic test serum CK may be tried for identifying MD.
Keywords: Creatine kinase, muscular dystrophy, gene deletions
|How to cite this article:|
Saha S, Joardar A, Roy S, Mondal T, Gangopadhyay G, Haldar D, Das HN. Serum creatine kinase and other profile of duchenne muscular dystrophy and becker muscular dystrophy: A cross-sectional survey in a tertiary care institution at Kolkata. CHRISMED J Health Res 2021;8:175-81
|How to cite this URL:|
Saha S, Joardar A, Roy S, Mondal T, Gangopadhyay G, Haldar D, Das HN. Serum creatine kinase and other profile of duchenne muscular dystrophy and becker muscular dystrophy: A cross-sectional survey in a tertiary care institution at Kolkata. CHRISMED J Health Res [serial online] 2021 [cited 2022 May 28];8:175-81. Available from: https://www.cjhr.org/text.asp?2021/8/3/175/339044
| Introduction|| |
Duchenne and its milder allelic form Becker muscular dystrophy (D/BMD) are common x-linked recessive neuromuscular disorders. Incidence of Duchenne muscular dystrophy (DMD) and BMD are estimated to be 1 in 3500 and 1 in 18,000 male births, respectively. These genetical diseases result from heterogeneous mutations in the locus of dystrophin gene. The dystrophin, the largest gene of human body consisting of 79 exons spans over a distance of more than 2.5 million base pairs is located at the Xp21 locus. Sequencing this big gene is time-consuming and fortunately, the deletions in it are distributed nonrandomly with many of the large gene deletions that occur in the dystrophin gene can be detected in specific hotspot areas of it. Clustering of hotspots is found mainly in two regions, i.e., about 20% at the 5' proximal portion of the gene (exons 1, 3, 4, 5, 8, 13, 19); and 80% at the mid-distal region, i.e., 42–45, 47, 48, 50–53.
The information in regard to molecular pathology and genetics has been available for the last two decades and is used for genetic counseling for the prevention of muscular dystrophies (MDs) in at risk families. During the past few years, polymerase chain reaction (PCR)-based genetic studies have become available in many parts of our country and health care providers along with parents' support groups are working hand in hand to diagnose and rehabilitate the victims. However, the sophisticated molecular diagnostics has not been made universally accessible in resource-poor countries. Moreover, it is costly as well as time-consuming which limits its application in biomarker assessment. In addition, the expression of dystrophin does not always constitute an accurate marker of clinical phenotypes.
Hence, some preliminary screening methods are still needed, especially for the economically marginalized section of the community predominantly seeking care from the peripheral health facilities.
Skeletal muscle is enriched with enzymes such as creatine kinase (CK), lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase. CK is usually increased in myopathies. In DMD and BMD, CK is increased in the preclinical stage. Practically all patients with of DMD or BMD exhibit higher serum level of CK. However, the level of increase is higher in DMD compared to that of the BMD. In DMD patients, CK levels are usually highly elevated and can range between 5000 and 150,000 IU/l (normal is <200 IU/l).
Despite the well-known disease symptoms, the diagnosis of MDs continues to be a challenge in general pediatric care settings and in pediatric neurology units as well, potentially because unsuspected myopathy among children with hypertransaminasemia can be erroneously attributed to liver disease for a long period before serum CK analysis and thus delaying its diagnosis and treatment.,,,,
In a resource-poor country like India, where molecular testing is not yet available at mass scale, CK is a good screening test for MDs in clinical practice because the levels are elevated in blood during active muscle fiber necrosis and injury. Thus, the disease can be diagnosed earlier before the victims become wheel-chair bound due to loss of ambulation, and by providing advanced treatment the quality life may be improved to these patients.
The objective of the present study was to compare CK levels between DMD and BMD, to correlate values of serum CK with number of deletions, duration of illness, and age of onset in patients of DMD and BMD and to establish a cut off value of CK for screening MD patients especially in centers where it is not possible to apply recombinant-DNA techniques.
| Materials and Methods|| |
This cross-sectional study was done in the Department of Biochemistry and neurogenetics unit of neurology of a tertiary care institute at Kolkata, India during a period of 3 years. After being clinically diagnosed by the Neurologist(s) DMD and BMD patients were subjected to serum CK estimation, chest radiograph, echocardiography, and electromyography (EMG) study. Patients with an elevated serum CK level and a positive EMG finding of myopathic pattern were included in the study. The patients clinically suspected but having normal CK level and with no historical evidence of X-linked inheritance; or having unrelated comorbidity which may influence the course and progression of the disease were excluded from the study. Then, the patients were subjected to genetic analysis after pretest counseling of parents and obtaining informed consent of them and assent from the participant's children, if applicable. Muscle biopsy was performed in patients where the genetic analysis was negative or inconclusive. Thus, 139 DMD and 50 BMD cases could be included in the study during the specified study period. A sample of 69 age-matched individuals who were suffering from disease(s) or medical condition(s) unlikely to influence the serum CK and having normal serum CK level was selected for the purpose of comparison. Baseline data regarding age, type of clinically diagnosed MDs, age of onset of disease, were gathered through interview using a predesigned questionnaire. The blood sample was collected from each of the participants through venepuncture for the estimation of serum CK level and DNA analysis. The estimation of CK was done by the Modified International Federation of Clinical Chemistry method.
For DNA analysis, genomic DNA was isolated from blood by phenol-chloroform method. Multiplex polymerase chain reactions (MPCR) were carried out for 18 exons which include Chamberlain-set and Beggs-set. The PCR amplification was carried out in a final reaction volume of 25 μl containing ~100 ng of genomic DNA, 1x PCR buffer, 2 mm MgCl2, 0.2 mm dNTPs, 10 picomoles forward primer, 10 picomoles reverse primer and volume make up with distilled water. Then, 1.25 units Taq polymerase was added to the PCR mix. PCR conditions were as follows: 5 min denaturation at 94°C was followed by 30 cycles of amplification (94°C for 30 s, 55°C for 30 s and 72°C for 30 s). The final extension was done at 72°C for 7 min. PCR products were resolved on 1% agarose gels, and the gels were analyzed for exonic deletions by the presence or absence of a corresponding band in the gel documentation system. The study was conducted after obtaining approval of the institutional review board.
Collected continuous data were described by estimation of mean, standard deviation (SD), median, range and the categorical data were summarized in proportion. Quantitative data were tested for their normal distribution by using Shapiro–Wilk test. For the purpose of inferential statistical analysis of skewed continuous data, nonparametric statistical test, Mann –Whitney U-test, and for categorical data Chi-square and Fisher's exact tests were applied. Receiver operating characteristic (ROC) curve analysis was done for choosing a cut-off value for the diagnosis of MDs. Area under the curve (AUC) was utilized to determine the performance of the test for the purpose of identifying MDs. P < 0.05 was considered as significant at 5% level of precision.
| Results|| |
The overall mean age of the study groups was 10.67 ± 6.83 (mean ± SD) years with median 8 and range of 3 months to 48 years compared to the corresponding figures of 11.52 ± 8.89, 14 and 1–43 years that of the comparison group. There was no difference in age across the study group as a whole and comparison groups (Mann–Whitney U = 4915.00, P = 0.679).
It was found that the proportion of younger patients was higher in DMD [Figure 1]. The difference was statistically robust (χ2 = 112.375 at df 2 with P = 0.000). Both the age of the participants, and the age of onset of MD were significantly lower in DMD group compared to that of the BMD group. Whereas, duration of illness and serum CK level were significantly higher and lower, respectively among the individuals belonging to BMD group compared to that of the DMD group [Table 1].
|Figure 1: Distribution of participants as per their age categories and type of muscular dystrophy (n = 189)|
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|Table 1: Distribution of respondents as per age, serum creatine kinase level, duration of illness and number of deletion (n=189)|
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Serum CK level among the comparison group was 210.33 ± 157.25 (mean ± SD) with a median of 165.5 and range 24–658. CK level was around 39 and 16 times higher than this in DMD and BMD subjects [Table 1].
Serum CK level decreases as age increases and around 22% and 7.0% variation in CK level in BMD and DMD groups were explained by increasing age [R2 values in [Figure 2]a, [Figure 2]b, [Figure 2]c.
|Figure 2: (a) Scatter diagram showing relation between overall age and serum creatine kinase level. (b) Scatter diagram showing relation between age and serum creatine kinase level among Becker muscular dystrophy patients. (c) Scatter diagram showing relation between age and serum creatine kinase level among Becker muscular dystrophy patients|
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Age was not found to have any correlation with serum CK level in comparison group whereas it showed a significant negative correlation in both types of MD. Moreover, age of onset (overall and DMD), duration of illness (overall) had an association with CK level. The serum level of CK wasn't influenced by the number of deletion detected [Table 2].
No statistically significant difference was revealed to exist across the DMD and BMD groups in regard to age-category and serum CK-category (χ2 = 0.76 at df 2 with P = 0.683).
A higher proportion of participants of DMD group was revealed to have normal level of serum CK, however, the difference was insignificant [Table 3].
|Table 3: Distribution of participants according to groups and serum creatine kinase level|
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The ROC curve analysis revealed that the AUC was 0.989 with P = 0.000 reflecting the fact that overall performance of serum CK level to diagnose both types of MD was very high with 97.3% sensitivity and 100% specificity at a cut-off value of 511.5 of CK level [Figure 3].
|Figure 3: Receiver operating characteristic curve of creatine kinase of serum level|
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As per analyses, the overall mean and median number of genetic deletion were 2.09 ± 2.44 (mean ± SD) and 1.0. The DMD and BMD groups were comparable in this regard [Table 1].
Genetic deletions were detected in 66.14% of the total 189 cases with 52.91% in the “distal hotspot,” 7.41% in the “proximal hotspot” and 6.35% at both regions. Among DMD and BMD groups genetic deletions were detected in 69.06% versus 58.0% overall. Out of the deletions, overall 79.2% in the distal region, 11.2% in proximal hotspot region, and 9.6% in both areas. In DMD and BMD groups 78.13% versus 82.76%, 10.42% versus 13.79%, and 11.46% versus 3.45% of all deletions took place in distal, proximal and both areas, respectively. No significant difference between DMD and BMD in regard to number of deletion in different hotspots could be established (χ2 = 2.01, 0.66, 0.03, and 2.16 with P = 0.156, 0.417, 0.851, and 0.141 at df 1 for overall deletion; deletion at distal, proximal and both hotspot regions).
Deletion of single, two, three, four, five, six, eight, fifteen, and seventeen exons were noted in 26.04%, 20.83%, 12.5%, 19.79%, 8.33%, 9.38%, 1.04%, 1.04%, and 1.04% of DMD cases, respectively. Whereas deletion of single, two, three, four, five, six exons occurred in 17.24%, 24.14%, 34.48%, 3.45%, 3.45%, and 17.24% of BMD victims.
In distal region, deletion of 43, 44, 45, 47, 48, 50, 51, and 52 exons in DMD occurred @ 3.2%, 1.98%, 13.89%, 11.9%, 21.43%, 21.03%, 15.48%, and 11.11%, respectively. In BMD deletion of exon 43, 45, 47, 48, 50, 51, and 52 took place @ 1.29%, 27.27%, 25.97%, 20.78%, 9.1%, 9.1%, and 6.49%, respectively. In proximal region of DMD deletions of exon 1, 3, 4, 6, 8, 12, 13, 17, and 19 were observed @ 6.78%, 13.56%, 6.78%, 13.56%, 13.56%, 11.86%, 10.17%, 8.47%, and 15.25%, respectively. In BMD, deletions of exons no. 3, 4, 6, 12, 13, and 19 in proximal region occurred @ 27.27%, 18.18%, 18.18%, 18.18%, 9.1%, and 9.1%, respectively. In regard to distal and proximal host spots, the deletions mostly happened at exon 48 and 45 and 19 and 3 in DMD and BMD, respectively.
The DMD and BMD groups were found to be comparable so far their regions of deletion were concerned [Table 4].
|Table 4: Distribution of respondents according to disease and hotspot region for deletion (n=189)|
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| Discussion|| |
The baseline characteristics of the participants of the present study, such as age of the MD patients, age of onset and presentation of disease, mean serum CK level, predominance of DMD cases, lower age in DMD group compared to that of the BMD group were found comparable to that of the other studies with little variation which might be due to varied study setting, study population, size of sample, and method of CK estimation.,
As per the results of the present study, abnormally elevated serum CK was universally present in both types of MD with significantly higher among the patients suffering from DMD.
Researchers referred CK as an easy, specific, and inexpensive marker of muscle disease. Among the MD patients higher serum CK is frequently accompanied by elevation of transaminases which provokes clinicians for unnecessary delay and expense for a complete evaluation of liver disease. The estimation of serum CK in any child with persistently elevated transaminases in the absence of other clinical or biochemical evidence of liver disease help identifying congenital MD in its early stage when symptoms are subtle.,,
According to studies, a grossly raised serum CK can be diagnostic of DMD with confidence before it is clinically apparent and excluded with certainty where it may have seemed clinically obvious.,,, Levels up to 100 times normal are found early stage of disease. Levels peak at 2–3 years of age and then decline with increasing age, due to progressive loss of dystrophic muscle fibers.
Hashim et al. reported 100% sensitivity and negative predictive value of serum CK with 91% and 88.8% specificity and positive predictive values of serum CK in affected DMD cases. Diagnostic efficiency was 94.1%. While in carriers of DMD, the sensitivity and negative predictive value of serum CK were 33.3%, and specificity and positive predictive were 100% with diagnostic efficiency of 50%. The authors referred serum CK as an excellent screening test for affected cases of DMD but not for carrier identification which requires PCR analysis to provide a safer diagnostic tool for genetic counseling and prenatal diagnosis.
However, even a grossly raised CK by itself is no index of severity or prognosis, since equally high levels can occur in milder X-linked Becker type of dystrophy.
This criticism against CK that despite being a good marker to screen for suspected dystrophinopathies it is not suitable to monitor disease progression and response to therapy has been mitigated to some extent by the observation of recent drisapersen trial showing the utility of CK as a secondary endpoint to assess efficacy.
Kley et al. cautioned against generalized statement about the universal association of MDs with high CK levels. There is a wide range of elevated CK levels among MD. Among the DMD and BMD subjects mean CK levels are about 10,000 U/L. Limb-girdle muscular dystrophy (LGMD) and certain of its recessive subtypes are associated with high CK levels in 5-digit range in contrast to dominant subtypes, for example, LGMD1A (myotilin), LGMD1D (DNAJB6), LGMD2J (titin) or facioscapulohumeral muscular dystrophy, and myotonic dystrophies in adults, and to oculopharyngeal muscular dystrophy CK levels are only slightly (<600 U/L) to moderately (600–1500 U/L) increased or even within normal range. Hence, family history, clinical phenotype, and extent of hyperCKemia can influence direction of further diagnostic work-up.
The present study results of no difference between DMD and BMD in regard to exon deletions at distal, proximal, and both regions might be due to higher proportion of severe BMD victims included in the study who had genetic insult close to that of DMD patients.
On the whole, the overall deletion rate of 66.14% with majority of deletion (79.2%) in “distal hotspot” region spanning over exons 43–52 are in agreement with the findings revealed in other researches.,
Again the overall deletion rates (69.06% vs. 58.0%), majority of deletion in the distal hotspot (78.13% vs. 82.76%), mostly occurred in the central rod domain spanning over between exon 45–52 (78.69% overall) in DMD and BMD patients participated in this study have concordance to what have been reported by Rao et al. and other Indian studies.,, Interestingly, the most frequently deleted exon as revealed in the present study is 48 in the central rod domain and is not similar to the observations made by other Indian studies which reported exon 49 and 50 as the most common deletion.,, It might be due to the variation in the ethnicity of the participants of the present study conducted in Eastern India whereas the above studies were carried out in Western part of India which can also explain the higher M-PCR failure rate of the present study (33.86%) to diagnose deletions in MD cases than the study carried out by Rao et al. (26.14%). However, from a study in Iran, Akbari et al. reported that the majority of deletions were identified in exons 47, 48, and 46.
Rao et al. also noticed phenotypic variability in patients who have shared even identical deletion pattern. Hence, they along with other researchers inferred that there is no apparent correlation between the size and/or location of the deletion and the severity or succession of the condition.,
In the current study, single gene deletions were noted in 26.04% and 17.24% of DMD and BMD patients and rest were more than one gene deletion (2–8 in the former and 2–6 in later) which is lower than what was reported by Barzegar et al. (33.3%) and rest had more than one deletion (range 2–8).
Devastating DMD needs an accurate and early diagnosis for initiation of prompt management, at least treatment with steroid for halting relentless march of muscle degradation and rehabilitation therapy. Reports indicate that significant delays in diagnosis of DMD persist due to reasons like poor awareness in family as well as among primary treatment providers, lack of access to sophisticated investigations, and scarcity of therapeutic options in resource-poor settings. Here, lies the role of serum CK which can be the building block of diagnostic framework for early detection, even in the neonatal period based on strong clinical suspicion. In early stage, CK can also differentiate DMD from its milder form i.e., BMD. Estimation of CK may be helpful for about 20% DMD cases where a routine genetic test is negative due to small scale point mutation and or deep intronic mutation leading to cryptic splicing requiring more sophisticated genetic tests like next-generation sequencing analysis or muscle biopsy in Western Blot technique or mRNA analysis. These tests are not always available in a poor settings and muscle biopsy is very painful hindering patients' cooperation. Lack of phenotypic and genotypic correlation is another emerging issue. Getting an exact genetic diagnosis of MD is complex, costly, and time-consuming. In resource-poor setting like India, serum CK level coupled with strong clinical correlation may be utilized to mitigate these constraints like delay management and starting rehabilitation pending the genetic results to be availed.
| Conclusion|| |
As per the present study, results and previous researches, the role of elevated serum CK cannot be overemphasized as the starting block of diagnostic array of clinically suspected dystrophinopathies. It can differentiate DMD and BMD cases. Overall performance and both sensitivity and specificity of serum CK level to diagnose both types of DMD and BMD was very high at a cut-off value of 511.5 U/L. Although the diagnosis of MD is to be confirmed by genetic testing for anticipating its severity, role of genetic counseling for prevention, and assessing scope of emerging genetic and molecular therapies; in case of a negative genetic test in resource-poor settings elevated serum CK coupled with strong clinical correlation may help to establish early diagnosis and starting management.
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Conflicts of interest
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]