Myoadenylate Deaminase Deficiency Research Articles

MYOADENYLATE DEAMINASE DEFICIENCY: DIAGNOSIS BY FOREARM ISCHEMIC EXERCISE TESTING AND PLASMA PURINE MEASUREMENTS.: 216

Quantitation of lactate and ammonia (NH3) production after forearm ischemic exercise (FIE) has been proposed as a screening test for myoadenylate deaminase (MAD) deficiency. Plasma lactate, NH3 and purines (adenosine inosine, hypoxanthine, xanthine) were determined 1, 3, 5 and 10 minutes after 90 seconds of FIE and correlated with exercise performance (∑ kg × sec), measured with a grip dynamometer, strain gauge and strip recorder.In 13 normals lactate and NH3 production correlated with exercise performance (r=0.76 and 0.72, respectively). Three patients with histochemically-defined MAD deficiency failed to generate NH3 despite increasing lactate and adequate performance. Retesting normals at submaximal performance produced lactate and NH3 generation patterns indistinguishable from those of the 3 patients. Normal subjects even with submaximal performance increased plasma purines from 10 to 38 μM after FIE. The MAD deficient patients raised their purine levels only 0-7 μM.These data demonstrate that submaximal exercise efforts by normals can give FIE test results indistinguisable from those of MAD deficient individuals if only lactate and NH3 are assessed and plasma purine measurements after FIE testing are effective in identifying the deficiency state. These results support the hypothesis that disordered purine metabolism occurs in patients with MAD deficiency.

MYOADENYLATE DEAMINASE DEFICIENCY AND McARDLE'S DISEASE: PLASMA ADENOSINE, INOSINE AND HYPOXANTHINE AFTER ISCHEMIC FOREARM EXERCISE: 196

Plasma adenosine, inosine and hypoxanthine concentrations were assayed in 7 controls, 5 myoadenylate deaminase deficient (MADD)patients and 6 McArdle patients before and after ischemic forearm exercise. The MADD patients showed a significantly lower increase of plasma inosine and hypoxanthine following exercise as compared to the controls, indicating diminished adenine nucleotide catabolism in the exercising MADD muscle. In the McArdle patients the increase in plasma inosine and hypoxanthine after exercise did not differ significantly from the values measured in the controls. The plasma adenosine increase was very low in all test groups and there were no significant differences.

Myoadenylate deaminase deficiency in children

Myoadenylate deaminase (MADA) is an enzyme which participates in the purine nucleotide cycle necessary for energy production in human skeletal muscle. Approximately 35 patients with deficiency of this enzyme have been reported; one-half experienced their initial difficulties in childhood. Children with “primary” MADA deficiency typically have symptoms including muscle cramps, stiffness, and post-exercise myalgia and weakness. In “secondary” MADA deficiency, the clinical findings have been variable with delayed motor development, hypotonia, cardiomyopathy, delayed speech development, and generalized weakness. In most cases creatine kinase determinations, nerve conduction velocity studies, and routine muscle histopathology have been normal. Diagnosis has been established by demonstrating an absence of MADA activity by either direct muscle enzyme assay or histochemical staining. In this report we describe a 12-year-old boy with primary MADA deficiency and contrast his symptoms with those of previously described pediatric patients.

Myoadenylate deaminase deficiency: Inherited and acquired forms

Myoadenylate deaminase deficiency, the most common of the known enzyme deficits of muscle, appears to occur in two forms. The primary type seems to be inherited as a complete gene block in an autosomal recessive pattern. Although occasionally diagnosed in infancy, when muscle biopsy is performed on a hypotonic but normoreflexic child, the deficiency is usually not symptomatic until adult or middle age, when muscle cramping and exercise intolerance develop. The skeletal muscle isozyme is immunologically, and presumably genetically, unique, and these patients have normal levels of adenylate deaminase in their other cells and tissues. A presumptive diagnosis can usually be made by an ischemic forearm exercise test, which shows a negligible increase in blood ammonia, despite a normal rise in lactate. Despite the absence of more than 99% of normal adenylate deaminase activity, the muscle biopsy shows no anatomic pathology, and other enzymes are at normal levels. These patients do not suffer progressive disease, and should be reassured, and encouraged to maintain physical activity. The heterozygous state is probably asymptomatic, except, perhaps, on extreme exercise, but may be associated with an increased incidence of malignant hyperthermia susceptibility. Since the gene defect is not rare, it is not surprising that some cases of the deficiency will be coincidentally associated with other neuromuscular disease. However, there is also a secondary form of myoadenylate deaminase deficiency, consequent to muscle damage from other disease. In this form, the residual activity is higher (1–10% of normal), may present rare foci of positive stain in the section, and reacts normally with antibody to the muscle isozyme. Other muscle enzymes are also depleted, although not as severely, and the prognosis in such cases is dictated by the primary disease. Since the heterozygous state is common, these patients might have been carriers, whose adenylate deaminase levels have been lowered to the deficient category by the advent of other neuromuscular disease.

Myoadenylate deaminase deficiency. Functional and metabolic abnormalities associated with disruption of the purine nucleotide cycle.

To assess the role of the purine nucleotide cycle in human skeletal muscle function, we evaluated 10 patients with AMP deaminase deficiency (myoadenylate deaminase deficiency; MDD). 4 MDD and 19 non-MDD controls participated in an exercise protocol. The latter group was composed of a patient cohort (n = 8) exhibiting a constellation of symptoms similar to those of the MDD patients, i.e., postexertional aches, cramps, and pains; as well as a cohort of normal, unconditioned volunteers (n = 11). The individuals with MDD fatigued after performing only 28% as much work as their non-MDD counterparts. Muscle biopsies were obtained from the four MDD patients and the eight non-MDD patients at rest and following exercise to the point of fatigue. Creatine phosphate content fell to a comparable extent in the MDD (69%) and non-MDD (52%) patients at the onset of fatigue. Following exercise the 34% decrease in ATP content of muscle from the non-MDD subjects was significantly greater than the 6% decrease in ATP noted in muscle from the MDD patients (P = 0.048). Only one of four MDD patients had a measurable drop in ATP compared with seven of eight non-MDD patients. At end-exercise the muscle content of inosine 5'-monophosphate (IMP), a product of AMP deaminase, was 13-fold greater in the non-MDD patients than that observed in the MDD group (P = 0.008). Adenosine content of muscle from the MDD patients increased 16-fold following exercise, while there was only a twofold increase in adenosine content of muscle from the non-MDD patients (P = 0.028). Those non-MDD patients in whom the decrease in ATP content following exercise was measurable exhibited a stoichiometric increase in IMP, and total purine content of the muscle did not change significantly. The one MDD patient in whom the decrease in ATP was measurable, did not exhibit a stoichiometric increase in IMP. Although the adenosine content increased 13-fold in this patient, only 48% of the ATP catabolized could be accounted for by the combined increases of adenosine, inosine, hypoxanthine, and IMP. Studies performed in vitro with muscle samples from seven MDD and seven non-MDD subjects demonstrated that ATP catabolism was associated with a fivefold greater increase in IMP in non-MDD muscle. There were significant increases in AMP and ADP content of the muscle from MDD patients following ATP catabolism in vitro, while there was no detectable increase in AMP or ADP in non-MDD muscle. Adenosine content of MDD muscle increased following ATP catabolism, but there was no detectable increase in adenosine content of non-MDD muscle following ATP catabolism in vitro. These studies demonstrate that AMP deaminase deficiency leads to reduced entry of adenine nucleotides into the purine nucleotide cycle during exercise. We postulate that the resultant disruption of the purine nucleotide cycle accounts for the muscle dysfunction observed in these patients.

Levels of adenylate deaminase, adenylate kinase, and creatine kinase in frozen human muscle biopsy specimens relative to type 1/type 2 fiber distribution: evidence for a carrier state of myoadenylate deaminase deficiency.

Myoadenylate deaminase deficiency is believed to reflect a genetic deficiency of skeletal muscle, but its pattern of inheritance has not been established. We examined, histochemically and by quantitative biochemical assay, muscle biopsy specimens from 3 putative carriers of this disorder. Adenylate kinase and creatine kinase were assayed in parallel with adenylate deaminase in order to establish enzyme activity ratios and the variation of each enzyme with fiber-type distribution. Control tissue consisted of 34 biopsy specimens without notable abnormalities from 30 patients, and included 4 specimen pairs with disparate fiber-type contributions. By linear regression analysis, adenylate deaminase level averaged 2.8-fold higher, and adenylate kinase 4.5-fold higher, in type 2 than in type 1 fibers, whereas creatine kinase level did not differ. The slopes of the regression lines resulting from analysis of the four specimen pairs from individual patients agreed well with the overall regression line in each plot. The 3 putative carriers had adenylate deaminase levels 2.5 to 5.7 times lower than the mean control value for their fiber-type distribution, but at least 20 times higher than their enzyme-deficient kinfolk. This finding indicates that a carrier state does exist, and that the deficiency state reflects an autosomal recessive inheritance pattern. Three additional biopsy specimens were excluded from evaluation when preliminary analysis showed elevated adenylate kinase/adenylate deaminase ratios that were outliers at the 1% level. This result suggests a carrier incidence of 10% in the muscle biopsy specimen population, which would markedly bias population estimates if undetected.

Myoadenylate deaminase deficiency: an enzyme defect in search of a disease.

The frequency of MAD deficiency in cases with exercise intolerance compared with the frequency in series of consecutive muscle biopsies suggests a relation between the deficiency and exercise intolerance. Deficiency cases can be presumed by an impaired NH3 production during ischaemic exercise. The ischaemic exercise test also gives information concerning the familial character of the deficiency.

Human myoadenylate deaminase deficiency.

This entity was first described, in 5 patients, in 1978, as the consequence of the introduction of an effective histoenzymatic stain1 for adenylate deaminase in frozen muscle biopsies. That report2 established the following: (1) The deficiency state was quite common, occurring in 1–2% of muscle biopsies, and accompanied by relatively mild, though persistent, symptoms of exertional myalgia. (2) Application of a sensitive solution assay3 verified that all 5 cases had less than 5% of the specific activity of adenylate deaminase in normal muscle biopsies, thus validating the histoenzymatic stain as a diagnostic tool. (3) There was no evidence of an enzyme inhibitor, by crossmixing studies of normal and deficient homogenates. (4) Affected patients had normal levels of adenylate deaminase in their red cells, indicating separate genetic control of the two isozymes. (5) Affected patients had normal skeletal muscle architecture and normal levels of other enzymes, indicating that the enzyme deficiency was specific, and was clearly not the cause of muscular dystrophy, as had often been suggested. (6) A simple provocative procedure, the lactateammonia-exercise-ratio (LAER test) demonstrated the physiological deficit in affected patients, and could be used for clinical diagnosis. (7) Skeletal muscle adenylate deaminase could be separated and identified, in its native state, by proper application of PAGE and the catalytic stain.KeywordsMuscular DystrophyMuscle BiopsyDeficiency StateMalignant HyperthermiaPurine Nucleotide CycleThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Myoadenylate deaminase deficiency—a nonfamilial, nondisease?

Myoadenylate deaminase deficiency—a nonfamilial, nondisease?

22 Myoadenylate Deaminase Deficiency (MADD). A Review of Thirty-five cases

22 Myoadenylate Deaminase Deficiency (MADD). A Review of Thirty-five cases

Myoadenylate deaminase deficiency or not?: Observations on two brothers with exercise-induced muscle pain

This paper describes 2 brothers with increasingly severe exercise-induced muscle pain and stiffness, beginning in adolescence. Histochemical studies showed that myoadenylate deaminase activity was absent in the propositus, but present in his younger brother. Biochemical examination of muscle homogenates confirmed these findings, with enzyme activity approximately 60% of the mean control value in the younger sibling. Red cell adenylate deaminase activity was normal in both cases. The possible relationship between the clinical and biochemical findings in these patients is discussed.

Immunologic distinction of human muscle adenylate deaminase from the isozyme(s) in human peripheral blood cells: Implications for myoadenylate deaminase deficiency

Rabbit antisera to human muscle adenylate deaminase efficiently precipitate this enzyme from crude homogenates of muscle from man, monkey, and horse, without affecting other enzymes and proteins in the sample. They fail to react, however, with the adenylate deaminase of purified human erythrocytes, granulocytes, lymphocytes, and platelets. The exclusive presence of an antigenic determinant in the muscle adenylate deaminase suggests that this isozyme is determined by a unique gene. Since patients with myoadenylate deaminase deficiency have normal levels of the enzyme in their erythrocytes and leukocytes, this constitutes the strongest evidence at present that the deficiency state is due to an inherited gene defect.

Myoadenylate deaminase deficiency: Muscle biopsy and muscle culture in a patient with gout

AMP deaminase activity was undetectable by a sensitive spectrophotometric assay in the muscle biopsy of a 37-year-old man with gout and exercise-related cramps and myalgia. Venous ammonia failed to rise after ischemic exercise, but the diagnostic value of this test is uncertain because changes of plasma ammonia after exercise varied greatly in different normal individuals. In the patient, AMP deaminase activity was normal not only in erythrocytes, leukocytes and cultured fibroblasts but also in muscle cultures. Presence of AMP deaminase in muscle cultures was probably due to the expression of a fetal isoenzyme under separate genetic control from adult muscle AMP deaminase.

Indicator enzyme assays: I. Adenylate deaminase: Principles and application to human muscle biopsies and blood cells

A multisample spectrophotometric assay for adenylate deaminase in the visible wavelength range has been developed, and the principles involved in optimizing assay conditions have been summarized. The assay was found to exhibit excellent stability characteristics, and was suitable for assay of crude (or purified) enzyme in a variety of tissues, including erythrocyte lysates. The assay has been tested with a number of substrate analogs, activators, and inhibitors, and by comparison with an ultraviolet absorption assay. The apparent K m for purified rabbit (and crude mouse) muscle adenylate deaminase was 0.4 m m. The assay was used to delineate an optimal extraction medium for the human muscle enzyme, which was then used to confirm the existence of myoadenylate deaminase deficiency and a probable carrier state. The assay was also used to compare the relative specific activities of muscle, granulocytes, lymphocytes, platelets, and erythrocytes, which were approximately 100, 20, 3, 2, 1.

Erratum: Myoadenylate Deaminase Deficiency: A New Disease of Muscle

In the report by W. N. Fishbein, V. W. Armbrustmacher, and J. L. Griffin, "Myoadenylate deaminase deficiency: A new disease of muscle" (5 May, p. 546), the unit in Table 2 should be "Enzyme (nmole/min) per milligram of protein."