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Hepatic failure in disorders of oxidative phosphorylation with neonatal onset
Volume 119 Number 6
8. Powars D, Overturf GD, Wilkins J. Infections in sickle cell and SC disease [Editorial]. J PEDIATR 1983;103:242. 9. Zarkowsky HS, Gallagher D, Gill FM, et al. Bacteremia in sickle hemoglobinopathies. J PEDIATR 1986; 109:517. 10. Moo-Penn W, Bechtel K, Jue D, et al. The presence of hemoglobin S and CH~rl~min an individual in the United States. Blood 1975;46:363.
Clinical and laboratory observations
951
11. Charache S, Zinkham WH, Dickerman JD, et al. Hemoglobin Be, SGphiladelphiaand SOArabdiseases. Am J Med 1977;62:439. 12. Gaston MH, Verter JI, Woods G, et al. Prophylaxis with oral penicillin in children with sickle cell anemia. N Engl J Med 1986;314:1593. 13. Pearson HA. Neonatal testing for sickle cell diseases: a historical and personal review. Pediatrics 1989;83(suppl):815.
Hepatic failure in disorders of oxidative phosphorylation with neonatal onset Val6rie Cormier, MD, Pierre Rustin, PhD,Jean-Paul Bonnefont, MD, Caroline Rambaud, MD, Anne Vassault, PhD, Daniel Rabier, PhD, Philippe Parvy, PhD,Sophie Couderc, MD, Fran~oise Parrot-Roulaud, PhD, Mireille Carr6, MD, Jean-Claude Risse, MD, C. Cahuzac, MD, Jean-Marie Saudubray, MD, Agn~s ROtig, PhD, Philippe Hubert, MD, and Arnold Munnich, MD, PhD From the H6pital des Enfants-Malades, Paris, Centre Hospitatier de Bordeaux, Bordeaux, Centre Hospitalier de Sens, Sens, and Centre Hospitalier de Creil, Creil, France
Oxidative phosphorylation includes the oxidation of fuel molecules by oxygen and the simultaneous transduction of energy to adenosine triphosphate. During the oxidation process, reducing equivalents are transferred from respiratory substrates ( N A D H , succinate) to oxygen by way of four multienzymatic complexes: N A D H - C o Q reductase, succinate-CoQ reductase, CoQ H2-cytochrome c reductase, and cytochrome c oxidase.l Inborn errors of oxidative phosphorylation have not been regarded as a cause of hepatic failure in infancy, although Boustany et al. 2 described a constitutive defect of oxidative phosphorylation (cytochrome c oxidase deficiency) manifesting as liver dysfunction in a child. Recently we observed hepatocellular dysfunction in three unrelated neonates with ketoacidotic coma related to defects in respiratory enzymes. We report here the clinical profiles of these patients and suggest genetic disorders of oxidative phosphorylation as possible causes of hepatic failure, especially in association
Supported by a Guigoz Foundation fellowship (Dr. Cormier). Submitted for publication Feb. 22, 1991; accepted July 5, 1991. Reprint requests: Arnold Munnich, MD, PhD, Unite de Recherches sur les Handicaps G6n&iques de l'Enfant, INSERM U-12, D6partement de P6diatrie and Laboratoire de Biochimie, HSpital des Enfants-Malades, 149 Rue de S6vres, 75743 Paris Cedex 15, France. 9/22/32271
with neurologic abnormalities and repeated attacks of ketoacidosis, in the neonate. CASE REPORTS Patient 1. A 3030 gm boy, born at term to first cousins, had se-
vere metabolic acidosis and ketosis with recurrent apnea and dehydration at 2 days of age (pH, 7.22; serum bicarbonate, 7.7 retool/ L). Hepatomegaly with abdominal enlargement and jaundice were present. Cholestasis and hepatic cellular dysfunction were noted (aspartate aminotransferase, 229 U/L; alanine aminotransferase, 235 U/L; bilirubin, 108 #mol/L [6.3 mg/dL]; alkaline phosCoQ L/P NADH
Coenzyme Q Lactate/pyruvate Nicotinamide adenine dinucleotide, reduced form
phatase, 300 U/L). Metabolic acidosis and hepatocellular dysfunction improved after 2 weeks but worsened again thereafter (coagulation factor V, 20%; serum proteins, 46 gm/L). Lethargy, hypotonia, poor spontaneous movements, and proximal tubulopathy were also noted. The patient died at 4 months of age after an episode of ketoacidotic coma and hepatic failure with liver enlargement, ascites, and edema. An elder brother had died at 3 months of age after a similar clinical course. Patient 2. A 2200 gm boy, born to first cousins after a 38-week pregnancy, had immediate apnea requiring intensive resuscitation (Apgar score of 1 at 1 minute). He recovered thereafter, but weak sucking and poor crying were noted. Recurrent episodes of hypoglycemia occurred in his first few days of life. When he was 10 days of age, a severe collapse occurred and was related to a bacterial infection; metabolic acidosis persisted despite intensive treatment
952
Clinical and laboratory observations
The Journal of Pediatrics December 1991
Table. Oxidation-reduction status and enzyme activities in liver and muscle tissues Patient
Plasma Lactate (mmol/L) Pyruvate (mmol/L) L / P molar ratio 3-Hydroxybutyrate (mmol/L) Acetoaeetate (mmol/L) 3-Hydroxybutyrate/acetoacetate molar ratio Urine (t~mol/mmol creatinine) Lactate 3-Hydroxybutyric acid Ethylmalonic acid Adipic acid Suberic acid Sebacic acid 3-Hydroxysebacic acid 4-Hydroxyphenyl lactic acid Liver Cytochrome c oxidase/succinate cytochrome c reductase Cytochrome c oxidase/NADH cytochrome c reductase Muscle Cytochrome c oxidase/succinate cytochrome c reductase Cytochrome c oxidase/NADH cytochrome r reductase
15 0.44 35 1.8 0.26 7 +++ +++ 75 166 71 205 220 4+
I
Patient 2
Patient 3
Control*
7.06 0.22 35.3 0.088 0.03 2.93
3.82 0.15 25.4 0.10 0.05 2
(n = 20) 0.63-2.44 0.045-0.19 <20 0,02-0.09 0.016-0.040 <2 (n = 20)
++++ +++ 0 33 8 0 0 --
--
0
--
0
-------
0.90
--
0.56
<3l <25 <16 0 <12 0 (n = 7) 3.07 +-- 0.29
2.36
--
0.62
3.22 • 0.54
1.40
2.25
1.56
3.07 _+ 0.21
--
1.85
3.5 _+ 0.70
(n = 7)
--
*Values are mean -+ SD, where applicable; elsewhere they are ranges.
(pH, 7.12; serum bicarbonate, 10 mmol/L). Severe hypotonia with hepatomegaly and liver failure were noted (aspartate aminotransferase, 93 U/L; alanine aminotransferase, 93 U/L; bilirubin, 226 #mol/L [ 13.2 mg/dl]; alkaline phosphatase, 300 U/L; coagulation factor V, 30%; serum proteins, 45 gin/L). This baby died at 3 months of age after a terminal episode of bepatocellular dysfunction with severe ascites. Patient 3. A 2990 gm girl, born to first cousins after a 41-week pregnancy, had an Apgar score at 1 minute of 2, for no obvious reason. Early feeding difficulties were present. The patient then had repeated episodes of hypotonia, drowsiness, metabolic acidosis (pH, 7.34; plasma bicarbonate, 11 retool/L), and mild liver involvement at 2 and at 4 months of age, with no severe liver enlargement or dysfunction (aspartate aminotransferase, 53 U/L; alanine aminotransferase, 40 U/L; serum proteins, 60 gm/L; coagulation factor V, 20%0). At 12 months of age, the patient had severe psychomotor retardation, blindness, cortical atrophy, and failure to thrive (-2.5 SD for weight and length). At 19 months, after a lung infection, she suddenly entered a deep, terminal coma. Liver enlargement and hepatocellular dysfunction were still moderate (coagulation factor V, 35%; factor II, 65%; factors VII and X, 60%). METHODS Plasma l a c t a t e / p y r u v a t e and ketone body molar ratios (/3-hydroxybutyrate/acetoacetate) were determined in pa-
tients and control subjects as indexes of oxidation reduction status in cytoplasm and mitochondria, respectively. 3 Spectrometric studies of muscle and liver mitochondria or homogenates were carried out as described4; the results are presented as ratios to cytochrome c oxidase activity, r a t h e r than as absolute values, because balanced respiratory enzyme activities are required for functional oxidative phosphorylation in vivo. Liver specimens obtained by needle biopsy and at postmortem examination were fixed in Bouin fluid. Sections were stained by hematoxylin and eosin and by special histochemical stains, including periodic acid-Schiff, trichrome, and Gordon-Sweet dyes for detection of reticulin fibers. Liver fragments were also frozen and stained by oil red O, for detection of lipid accumulation. RESULTS P e r m a n e n t hyperlactatemia and ketosis with high L / P and ketone body molar ratios in plasma were considered suggestive of a genetic defect in oxidative phosphorylation in all three patients (Table). Subsequent determination of respiratory enzyme activities in the liver provided evidence of markedly deficient cytochrome c oxidase activities in patients 1 and 3 (Table). Histopathologic examinations of the liver showed t h a t
Volume 119 Number 6
Clinical and laboratory observations
953
Figure. Histopathologic examination of liver tissue. A and B, Trichrome stain in liver of patients 1 and 3, respectively. Note macrovesicular and microvesicular inclusions. C, Gordon-Sweet stain of liver specimen from patient 1. D, Periodic acid-Schiff staining in liver of patient 3. Note centrilobular distribution of vacuoles and disappearance of glycogen. hepatocytes were swollen with macrovesicular and microvesicular lipid vacuoles (Figure). A panlobular steatosis, with mild intracellular and intercellular cholestasis, was present in patient 1 (Figure, A); in patient 3 a largely centrilobular distribution of the vacuoles was noted (Figure, B). No cytolysis, portal fibrosis, or inflammatory infiltrates were found in either patient (shown for patient 1 in Figure, C) but the periodic acid-Schiff staining showed the complete disappearance of glycogen in centrilobular hepatocytes (Figure, D). Cytochrome c oxidase activities in skeletal muscle were altered to a lesser extent (Table); no lipidosis or mitochondrial abnormalities were noted in this tissue (not shown). Absence of suecinylacetone or reducing substances in the urine ruled out the diagnoses of tyrosinemia, galactosemia, and fructosemia. Gas chromatography-mass spectrometry of the urine detected large amounts of lactate and ketone bodies, but revealed only small amounts of Krebs-cycle intermediary acids (Table). Plasma and urinary carnitine
concentrations were normal (not shown). Finally, to rule out a nonspecific effect of liver dysfunction on oxidative phosphorylation, we studied oxidation-reduction statuses in plasma of five infants with hepatic failure from other causes. No permanent hyperlactatemia or elevation of L/P and ketone body molar ratios was observed (not shown). DISCUSSION We have identified liver involvement in three unrelated neonates with early-onset defects in oxidative phosphorylation. Liver involvement ranged in severity from rapidly fatal hepatic failure, with major liver enlargement, ascites, and edema, to slowly progressive hepatocellular dysfunction. In all three neonates the liver disease was associated with a poor neurologic condition, with repeated episodes of ketoacidotic coma beginning immediately after birth. No symptom-free period was noted, suggesting an antenatal expression of the symptoms.
954
Clinical and laboratory observations
Persistent hyperlactatemia with high L/P and ketone body molar ratios in plasma provided evidence of a major accumulation of reducing equivalents in both cytoplasm and mitochondria. This observation, pointing to a possible defect of the mitochondrial energy supply, led us to investigate the respiratory enzyme activities in the liver. Eventually, we ascribed the hepatoeellular dysfunction of our patients to a constitutional defect of oxidative phosphorylation. In addition, consanguinity of the parents and familial recurrence of the disease were highly suggestive of an autosomal recessive inheritance of the trait. In the past few years, many patients with disorders of oxidative phosphorylation have been described. Encephalomyopathies and neuromuscular diseases 5 were first reported. It is now clear, however, that the clinical expression of these diseases is extremely variable because efficient oxidative phosphorylation is required in all tissues and organs. Indeed, de Toni-Faneoni syndrome,6 eardiomyopathy,7 and pancytopenia with exocrine pancreatic dysfunction8, 9 have been recognized as the onset symptoms in several patients with progressive multisystemic involvement from disorders in oxidative phosphorylation occurring in infancy. Inborn errors of oxidative phosphorylation have rarely been recognized as a cause of hepatic failure in the neonate.2 We must be aware of this early cause of severe hepatoeellular dysfunction. Systematic screening for ketonuria, along with plasma L/P and ketone body molar ratios, allows diagnosis of this condition and thus should be included in the clinical evaluation of hepatic failure in neonates. We thank the members of AssociationFranqaise contre les Myopathies for their constant support.
The Journal of Pediatrics December 1991 REFERENCES
1. Tzagoloff A. Mitochondria. New York: Plenum Press, 1983: 342. 2. Boustany RN, Aprille JR, Halperin J, Levy H, DeLong GR. Mitochondrial cytochrome deficiencypresenting as a myopathy with hypotonia, external ophthalmoplegia, and lactic acidosis in an infant and as fatal hepatopathy in a second cousin. Ann Neurol 1983;14:462-70. 3. Vassault A, BonnefontJP, Specola N, et al. Lactate, pyruvate, and ketone bodies. In: Hommes FA, ed. Techniques in diagnostic human biochemical genetics: a laboratory manual. New York: Wiley-Liss, 1991:285. 4. Chr6tien D, BourgeronT, R6tig A, et al. The measurement of the rotenone-sensitiveNADH cytochromec reductase activity in mitochondria isolated from minute amount of human skeletal muscle. Biochem Biophys Res Commun 1990;173:2633. 5. Wallace DC. Mitochondrial DNA mutations and neuromuscular disease. Trends Genet 1989;5:9-13. 6. Sped W, Ruitenbeek W, Trijbels JM, et al. Mitochondrial myopathy with lactic acidemia, Fanconi-de Toni-Debr~ syndrome, and a disturbed suceinate cytochromee oxidoreduetase activity. Eur J Pediatr 1988;147:418-21. 7. Hoppel CL, Kerr DS, Dahms B, Roessman U. Deficiencyof the reduced nieotinamideadenine dinucleotidedehydrogenase component of complex I of mitochondrial electron transport: fatal infantile lactic acidosis and hypermetabolism with skeletal-cardiac myopathy and encephalopathy. J Clin Invest 1987;80:71-7. 8. R6tig A, Cormier V, Blanche S, et al. Pearson's marrow-pancreas syndrome: a multisystem mitochondrial disorder in infancy. J Clin Invest 1990;86:1601-8. 9. Cormier V, R~StigA, Rasore Quartino A, et al. Widespread multitissue deletionsof the mitochondrial genome in the Pearson marrow-pancreas syndrome. J PEDIATR I990;tt7:599602.
8. Powars D, Overturf GD, Wilkins J. Infections in sickle cell and SC disease [Editorial]. J PEDIATR 1983;103:242. 9. Zarkowsky HS, Gallagher D, Gill FM, et al. Bacteremia in sickle hemoglobinopathies. J PEDIATR 1986; 109:517. 10. Moo-Penn W, Bechtel K, Jue D, et al. The presence of hemoglobin S and CH~rl~min an individual in the United States. Blood 1975;46:363.
Clinical and laboratory observations
951
11. Charache S, Zinkham WH, Dickerman JD, et al. Hemoglobin Be, SGphiladelphiaand SOArabdiseases. Am J Med 1977;62:439. 12. Gaston MH, Verter JI, Woods G, et al. Prophylaxis with oral penicillin in children with sickle cell anemia. N Engl J Med 1986;314:1593. 13. Pearson HA. Neonatal testing for sickle cell diseases: a historical and personal review. Pediatrics 1989;83(suppl):815.
Hepatic failure in disorders of oxidative phosphorylation with neonatal onset Val6rie Cormier, MD, Pierre Rustin, PhD,Jean-Paul Bonnefont, MD, Caroline Rambaud, MD, Anne Vassault, PhD, Daniel Rabier, PhD, Philippe Parvy, PhD,Sophie Couderc, MD, Fran~oise Parrot-Roulaud, PhD, Mireille Carr6, MD, Jean-Claude Risse, MD, C. Cahuzac, MD, Jean-Marie Saudubray, MD, Agn~s ROtig, PhD, Philippe Hubert, MD, and Arnold Munnich, MD, PhD From the H6pital des Enfants-Malades, Paris, Centre Hospitatier de Bordeaux, Bordeaux, Centre Hospitalier de Sens, Sens, and Centre Hospitalier de Creil, Creil, France
Oxidative phosphorylation includes the oxidation of fuel molecules by oxygen and the simultaneous transduction of energy to adenosine triphosphate. During the oxidation process, reducing equivalents are transferred from respiratory substrates ( N A D H , succinate) to oxygen by way of four multienzymatic complexes: N A D H - C o Q reductase, succinate-CoQ reductase, CoQ H2-cytochrome c reductase, and cytochrome c oxidase.l Inborn errors of oxidative phosphorylation have not been regarded as a cause of hepatic failure in infancy, although Boustany et al. 2 described a constitutive defect of oxidative phosphorylation (cytochrome c oxidase deficiency) manifesting as liver dysfunction in a child. Recently we observed hepatocellular dysfunction in three unrelated neonates with ketoacidotic coma related to defects in respiratory enzymes. We report here the clinical profiles of these patients and suggest genetic disorders of oxidative phosphorylation as possible causes of hepatic failure, especially in association
Supported by a Guigoz Foundation fellowship (Dr. Cormier). Submitted for publication Feb. 22, 1991; accepted July 5, 1991. Reprint requests: Arnold Munnich, MD, PhD, Unite de Recherches sur les Handicaps G6n&iques de l'Enfant, INSERM U-12, D6partement de P6diatrie and Laboratoire de Biochimie, HSpital des Enfants-Malades, 149 Rue de S6vres, 75743 Paris Cedex 15, France. 9/22/32271
with neurologic abnormalities and repeated attacks of ketoacidosis, in the neonate. CASE REPORTS Patient 1. A 3030 gm boy, born at term to first cousins, had se-
vere metabolic acidosis and ketosis with recurrent apnea and dehydration at 2 days of age (pH, 7.22; serum bicarbonate, 7.7 retool/ L). Hepatomegaly with abdominal enlargement and jaundice were present. Cholestasis and hepatic cellular dysfunction were noted (aspartate aminotransferase, 229 U/L; alanine aminotransferase, 235 U/L; bilirubin, 108 #mol/L [6.3 mg/dL]; alkaline phosCoQ L/P NADH
Coenzyme Q Lactate/pyruvate Nicotinamide adenine dinucleotide, reduced form
phatase, 300 U/L). Metabolic acidosis and hepatocellular dysfunction improved after 2 weeks but worsened again thereafter (coagulation factor V, 20%; serum proteins, 46 gm/L). Lethargy, hypotonia, poor spontaneous movements, and proximal tubulopathy were also noted. The patient died at 4 months of age after an episode of ketoacidotic coma and hepatic failure with liver enlargement, ascites, and edema. An elder brother had died at 3 months of age after a similar clinical course. Patient 2. A 2200 gm boy, born to first cousins after a 38-week pregnancy, had immediate apnea requiring intensive resuscitation (Apgar score of 1 at 1 minute). He recovered thereafter, but weak sucking and poor crying were noted. Recurrent episodes of hypoglycemia occurred in his first few days of life. When he was 10 days of age, a severe collapse occurred and was related to a bacterial infection; metabolic acidosis persisted despite intensive treatment
952
Clinical and laboratory observations
The Journal of Pediatrics December 1991
Table. Oxidation-reduction status and enzyme activities in liver and muscle tissues Patient
Plasma Lactate (mmol/L) Pyruvate (mmol/L) L / P molar ratio 3-Hydroxybutyrate (mmol/L) Acetoaeetate (mmol/L) 3-Hydroxybutyrate/acetoacetate molar ratio Urine (t~mol/mmol creatinine) Lactate 3-Hydroxybutyric acid Ethylmalonic acid Adipic acid Suberic acid Sebacic acid 3-Hydroxysebacic acid 4-Hydroxyphenyl lactic acid Liver Cytochrome c oxidase/succinate cytochrome c reductase Cytochrome c oxidase/NADH cytochrome c reductase Muscle Cytochrome c oxidase/succinate cytochrome c reductase Cytochrome c oxidase/NADH cytochrome r reductase
15 0.44 35 1.8 0.26 7 +++ +++ 75 166 71 205 220 4+
I
Patient 2
Patient 3
Control*
7.06 0.22 35.3 0.088 0.03 2.93
3.82 0.15 25.4 0.10 0.05 2
(n = 20) 0.63-2.44 0.045-0.19 <20 0,02-0.09 0.016-0.040 <2 (n = 20)
++++ +++ 0 33 8 0 0 --
--
0
--
0
-------
0.90
--
0.56
<3l <25 <16 0 <12 0 (n = 7) 3.07 +-- 0.29
2.36
--
0.62
3.22 • 0.54
1.40
2.25
1.56
3.07 _+ 0.21
--
1.85
3.5 _+ 0.70
(n = 7)
--
*Values are mean -+ SD, where applicable; elsewhere they are ranges.
(pH, 7.12; serum bicarbonate, 10 mmol/L). Severe hypotonia with hepatomegaly and liver failure were noted (aspartate aminotransferase, 93 U/L; alanine aminotransferase, 93 U/L; bilirubin, 226 #mol/L [ 13.2 mg/dl]; alkaline phosphatase, 300 U/L; coagulation factor V, 30%; serum proteins, 45 gin/L). This baby died at 3 months of age after a terminal episode of bepatocellular dysfunction with severe ascites. Patient 3. A 2990 gm girl, born to first cousins after a 41-week pregnancy, had an Apgar score at 1 minute of 2, for no obvious reason. Early feeding difficulties were present. The patient then had repeated episodes of hypotonia, drowsiness, metabolic acidosis (pH, 7.34; plasma bicarbonate, 11 retool/L), and mild liver involvement at 2 and at 4 months of age, with no severe liver enlargement or dysfunction (aspartate aminotransferase, 53 U/L; alanine aminotransferase, 40 U/L; serum proteins, 60 gm/L; coagulation factor V, 20%0). At 12 months of age, the patient had severe psychomotor retardation, blindness, cortical atrophy, and failure to thrive (-2.5 SD for weight and length). At 19 months, after a lung infection, she suddenly entered a deep, terminal coma. Liver enlargement and hepatocellular dysfunction were still moderate (coagulation factor V, 35%; factor II, 65%; factors VII and X, 60%). METHODS Plasma l a c t a t e / p y r u v a t e and ketone body molar ratios (/3-hydroxybutyrate/acetoacetate) were determined in pa-
tients and control subjects as indexes of oxidation reduction status in cytoplasm and mitochondria, respectively. 3 Spectrometric studies of muscle and liver mitochondria or homogenates were carried out as described4; the results are presented as ratios to cytochrome c oxidase activity, r a t h e r than as absolute values, because balanced respiratory enzyme activities are required for functional oxidative phosphorylation in vivo. Liver specimens obtained by needle biopsy and at postmortem examination were fixed in Bouin fluid. Sections were stained by hematoxylin and eosin and by special histochemical stains, including periodic acid-Schiff, trichrome, and Gordon-Sweet dyes for detection of reticulin fibers. Liver fragments were also frozen and stained by oil red O, for detection of lipid accumulation. RESULTS P e r m a n e n t hyperlactatemia and ketosis with high L / P and ketone body molar ratios in plasma were considered suggestive of a genetic defect in oxidative phosphorylation in all three patients (Table). Subsequent determination of respiratory enzyme activities in the liver provided evidence of markedly deficient cytochrome c oxidase activities in patients 1 and 3 (Table). Histopathologic examinations of the liver showed t h a t
Volume 119 Number 6
Clinical and laboratory observations
953
Figure. Histopathologic examination of liver tissue. A and B, Trichrome stain in liver of patients 1 and 3, respectively. Note macrovesicular and microvesicular inclusions. C, Gordon-Sweet stain of liver specimen from patient 1. D, Periodic acid-Schiff staining in liver of patient 3. Note centrilobular distribution of vacuoles and disappearance of glycogen. hepatocytes were swollen with macrovesicular and microvesicular lipid vacuoles (Figure). A panlobular steatosis, with mild intracellular and intercellular cholestasis, was present in patient 1 (Figure, A); in patient 3 a largely centrilobular distribution of the vacuoles was noted (Figure, B). No cytolysis, portal fibrosis, or inflammatory infiltrates were found in either patient (shown for patient 1 in Figure, C) but the periodic acid-Schiff staining showed the complete disappearance of glycogen in centrilobular hepatocytes (Figure, D). Cytochrome c oxidase activities in skeletal muscle were altered to a lesser extent (Table); no lipidosis or mitochondrial abnormalities were noted in this tissue (not shown). Absence of suecinylacetone or reducing substances in the urine ruled out the diagnoses of tyrosinemia, galactosemia, and fructosemia. Gas chromatography-mass spectrometry of the urine detected large amounts of lactate and ketone bodies, but revealed only small amounts of Krebs-cycle intermediary acids (Table). Plasma and urinary carnitine
concentrations were normal (not shown). Finally, to rule out a nonspecific effect of liver dysfunction on oxidative phosphorylation, we studied oxidation-reduction statuses in plasma of five infants with hepatic failure from other causes. No permanent hyperlactatemia or elevation of L/P and ketone body molar ratios was observed (not shown). DISCUSSION We have identified liver involvement in three unrelated neonates with early-onset defects in oxidative phosphorylation. Liver involvement ranged in severity from rapidly fatal hepatic failure, with major liver enlargement, ascites, and edema, to slowly progressive hepatocellular dysfunction. In all three neonates the liver disease was associated with a poor neurologic condition, with repeated episodes of ketoacidotic coma beginning immediately after birth. No symptom-free period was noted, suggesting an antenatal expression of the symptoms.
954
Clinical and laboratory observations
Persistent hyperlactatemia with high L/P and ketone body molar ratios in plasma provided evidence of a major accumulation of reducing equivalents in both cytoplasm and mitochondria. This observation, pointing to a possible defect of the mitochondrial energy supply, led us to investigate the respiratory enzyme activities in the liver. Eventually, we ascribed the hepatoeellular dysfunction of our patients to a constitutional defect of oxidative phosphorylation. In addition, consanguinity of the parents and familial recurrence of the disease were highly suggestive of an autosomal recessive inheritance of the trait. In the past few years, many patients with disorders of oxidative phosphorylation have been described. Encephalomyopathies and neuromuscular diseases 5 were first reported. It is now clear, however, that the clinical expression of these diseases is extremely variable because efficient oxidative phosphorylation is required in all tissues and organs. Indeed, de Toni-Faneoni syndrome,6 eardiomyopathy,7 and pancytopenia with exocrine pancreatic dysfunction8, 9 have been recognized as the onset symptoms in several patients with progressive multisystemic involvement from disorders in oxidative phosphorylation occurring in infancy. Inborn errors of oxidative phosphorylation have rarely been recognized as a cause of hepatic failure in the neonate.2 We must be aware of this early cause of severe hepatoeellular dysfunction. Systematic screening for ketonuria, along with plasma L/P and ketone body molar ratios, allows diagnosis of this condition and thus should be included in the clinical evaluation of hepatic failure in neonates. We thank the members of AssociationFranqaise contre les Myopathies for their constant support.
The Journal of Pediatrics December 1991 REFERENCES
1. Tzagoloff A. Mitochondria. New York: Plenum Press, 1983: 342. 2. Boustany RN, Aprille JR, Halperin J, Levy H, DeLong GR. Mitochondrial cytochrome deficiencypresenting as a myopathy with hypotonia, external ophthalmoplegia, and lactic acidosis in an infant and as fatal hepatopathy in a second cousin. Ann Neurol 1983;14:462-70. 3. Vassault A, BonnefontJP, Specola N, et al. Lactate, pyruvate, and ketone bodies. In: Hommes FA, ed. Techniques in diagnostic human biochemical genetics: a laboratory manual. New York: Wiley-Liss, 1991:285. 4. Chr6tien D, BourgeronT, R6tig A, et al. The measurement of the rotenone-sensitiveNADH cytochromec reductase activity in mitochondria isolated from minute amount of human skeletal muscle. Biochem Biophys Res Commun 1990;173:2633. 5. Wallace DC. Mitochondrial DNA mutations and neuromuscular disease. Trends Genet 1989;5:9-13. 6. Sped W, Ruitenbeek W, Trijbels JM, et al. Mitochondrial myopathy with lactic acidemia, Fanconi-de Toni-Debr~ syndrome, and a disturbed suceinate cytochromee oxidoreduetase activity. Eur J Pediatr 1988;147:418-21. 7. Hoppel CL, Kerr DS, Dahms B, Roessman U. Deficiencyof the reduced nieotinamideadenine dinucleotidedehydrogenase component of complex I of mitochondrial electron transport: fatal infantile lactic acidosis and hypermetabolism with skeletal-cardiac myopathy and encephalopathy. J Clin Invest 1987;80:71-7. 8. R6tig A, Cormier V, Blanche S, et al. Pearson's marrow-pancreas syndrome: a multisystem mitochondrial disorder in infancy. J Clin Invest 1990;86:1601-8. 9. Cormier V, R~StigA, Rasore Quartino A, et al. Widespread multitissue deletionsof the mitochondrial genome in the Pearson marrow-pancreas syndrome. J PEDIATR I990;tt7:599602.