Tyrosinemia type I - Diagnostic issues and prenatal diagnosis
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《美国医学杂志》
1 Department of Genetic Medicine, Sir Ganga Ram Hospital, New Delhi, India
2 Biochimiste Clinique Laboratoire de Genetique CHUQ Pavillon CHUL 2705, Boul. Laurier Sainte-Foy, Quebec, Canada
3 Clinical Chemistry, Birmingham Children's Hospital, Birmingham, United Kingdom
Abstract
A fifteen-month-old boy, born to consanguineously married couple, presented with asymptomatic hepatomegaly. Investigations revealed mildly deranged liver functions, necroinflammatory changes and cirrhosis on liver biopsy, a markedly raised alpha feto protein and tyrosine levels in plasma and a generalized aminoaciduria. His diagnosis of hereditary tyrosinemia was established on findings of raised serum and urine succinylacetone, and a deficient activity of fumaryl acetoacetate hydroxylase enzyme. Prenatal diagnosis of hereditary tyrosinemia was performed in a subsequent pregnancy in this family from India.
Keywords: Tyrosinemia type 1; Fumaryl acetoacetate hydroxylase enzyme; Prenatal diagnosis
Tyrosinemia type I (hepatorenal tyrosinemia, OMIM No. 276700) is a rare autosomal recessive disorder, with clinical and pathological manifestations involving mainly the liver, kidney, and peripheral nerves.[1] The clinical findings range from severe hepatocellular dysfunction in early infancy to chronic liver disease. The disorder is common in Quebec (1 in 16,786 live births) and Scandinavia, with a worldwide incidence of 1/100,000 to 1/120,000 population.[2],[3] There have been few reports from India although none has been based on enzyme assay and succinylacetone levels, which are confirmatory for diagnosis. [4],[5],[6] We present a case confirmed with enzyme assay, and report prenatal diagnosis of tyrosinemia in the mother of the index case.
Case Report
A fifteen-month-old boy was referred for evaluation in view of persistent hepatomegaly. He was born to a consanguineously married couple (uncle - niece marriage) and was the only child. The antenatal and perinatal periods were uneventful. He came to medical attention at six months of age, when the family pediatrician noted him to have hepatomegaly on a routine check-up. At eight months of age there was an episode of fever, with constipation during which he had a typical febrile seizure. There were no other symptoms. He was gaining all milestones appropriately for age. The child was immunized for age including for Hepatitis A and B. Dietary history was largely adequate in calories and proteins, except for history of loss of appetite, off and on. The illness remained static from identification at 6 months to presentation at 15 months.
Examination revealed a healthy looking child with weight of 13 kg and height 82 cm (normal for age). General physical examination was unremarkable with no dysmorphic facies. The child had a firm hepatomegaly,
3-cm below the costal margin in midclavicular line. The spleen was not palpable. There was no free fluid in the abdomen. Examination of cardiovascular, respiratory and central nervous system revealed no abnormality.
The investigations performed were as follows: hemoglobin 10.1 gm/dl, total leukocyte count 10,700 /cu.mm, differential count neutrophils 34%, lymphocytes 60%, monocytes 04%, and eosinophils 02%, peripheral smear - predominantly microcytic hypochromic cells with target cells, RBC indices suggestive of beta - thalassemia trait and blood sugar 60 mg/dl. Renal functions (BUN and creatinine) and serum electrolytes were normal. Liver function tests showed mild derangement; prothrombin time was 14.2 sec (control 12 seconds). There was mild derangement in liver enzymes with SGOT of 58 and SGPT of 108 IU/ml. Urine reducing substances were negative; there was generalized aminoaciduria on thin layer chromatography, and plasma tyrosine measured by HPLC was raised (3340 micromol/liter, normal range 7-127).
An ultrasound study of the abdomen revealed multiple hypoechoic lesions in both lobes of liver (upto 9 mm) and mild splenomegaly, both kidneys were normal in size and echotexture. CT scan abdomen corroborated the findings of ultrasound. MRI showed diffuse hepatic parenchymal disorder with micronodular lesions suggestive of cirrhosis of liver with regenerating nodules. Liver biopsy showed cores of liver tissue dissected by thin bridging fibrous septa into small nodules amounting to established cirrhosis. There was macrovesicular steatosis affecting about 50% of hepatocytes. There was no definite evidence of storage disorder, and necroinflammatory activity was noted raising a suspicion of tyrosinemia. Bone marrow aspiration showed normal results. The serum alpha feto protein (AFP) was markedly raised (41050 ng/ml); and there was a normal level of sphingomyelinase enzyme (0.79 nmol/hour/ mg of protein) and serum alpha-1-anti-trypsin levels (3950 mg/L). Blood succinyl acetone, measured indirectly by its inhibition of porphobilinogen synthase-delta-aminolevulinate dehydratase reaction,[7] was 9.0 micromol/L (normal <2.5), and urine succinyl acetone was 4.5 micromol/L (normal < 1). Enzyme fumaryl acetoacetate hydroxylase (FAH), measured by ELISA, using a specific anti-human FAH antibody[8], was abnormal with <5% of normal control activity noted on two occasions on two blood spots. These results confirmed the diagnosis of hereditary tyrosinemia type 1 (HT1). Therapy with 2-(nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC) was advised. The family was provided genetic counseling and explained the inheritance with 25% risk of recurrence in a future pregnancy, and informed that prenatal diagnosis would be possible.
The family consulted us during pregnancy for a prenatal diagnosis of HT1. Initial gene studies for the 4 common mutations (G192T, IVS12t 5G>A, IVS 6_1G>T and 1009G>A) reported among Indians and Pakistanis in the United Kingdom[9] were negative. At 12 weeks pregnancy, chorionic villous sampling (CVS) was carried out and the cleaned CV was then shipped to Birmingham in dry ice. FAH enzyme assay was performed on the CV sample. The result revealed a normal activity of FAH enzyme in uncultured CV (1.57) as compared to value in control of 1.50, the normal range of the enzyme in the CVS being 1.07 - 2.98, and the range for affected fetus <0.45.[10] These results excluded an affected fetus with HT1.
Discussion
Hepatorenal tyrosinemia HT1 (OMIM 276700) is a clinically severe inborn error that principally affects liver, kidney, and peripheral nerve.[1] It is one of the best-documented inborn errors of metabolism and has the highest incidence of developing hepatocellular carcinoma in the chronic form.[11] The first case of typical clinical and biochemical picture of hepatorenal tyrosinemia was described by Sakai et al in 1957.[12] Since then, there have been over 100 case reports appearing in literature. Reports from the Indian subcontinent are few and without enzyme assay.[4],[5],[6] HT1 is commonly suspected in India[4] but is under-diagnosed due to lack of availability of confirmatory tests.
The disease typically manifests in early infancy with acute hepatic crisis with hepatomegaly and bleeding diathesis precipitated by intercurrent illnesses inducing a catabolic state.[13] The acute crisis may resolve spontaneously but usually persists as hepatomegaly, coagulation abnormalities and failure to thrive. Cirrhosis of liver, hepatocellular carcinoma and death eventually occur early in life. Other features of tyrosinemia are peripheral neuropathy resembling acute porphyria and renal manifestations.[13]
The diagnosis in this patient is based on persistent asymptomatic firm hepatomegaly, a mildly deranged liver functions, very high AFP levels, high tyrosine levels in plasma with urinary aminoaciduria, liver findings of macrovesicular steatosis, micronodular lesions suggestive of cirrhosis with necro-inflammatory changes on liver biopsy. Raised plasma and urine succinylacetone levels and a deficient enzyme activity of FAH further confirmed the diagnosis and a pre-requisite for a subsequent prenatal diagnosis.[9]
Molecular diagnosis is possible and is the preferred technique for prenatal diagnosis. FAH gene is located on chromosome 15 q and has 14 exons.[1] Since the first report of the missense mutation n161 in the FAH mRNA, many mutations have been identified causing the disease.[1] Of these, there are 4 common mutations observed in subjects from the Indian Subcontinent.[9]
Liver transplant is curative for the disorder, and prior to NTBC it was the mainstay of therapy. NTBC has revolutionized the therapy as it is effective within hours and abolishes or markedly diminishes the risk of hepatic or neurologic decompensation.[1] Major issues regarding NTBC is confirmation of diagnosis, difficulties in import, and the cost involved.
Prenatal diagnosis (PND) can be performed using three techniques. The first report of prenatal diagnosis of HT1 was by measuring succinylacetone in amniotic fluid in 1982[14] and is still being used. Second method of PND is by enzyme assay (FAH) in chorionic villi taken at 10-12 weeks of gestation.[15] PND by molecular technology is the most accurate method in cases where the mutations are known in the FAH gene. The concerned family was tested using the enzyme assay method as no mutations could be identified in the short time period available between the diagnosis of the child with disease and prenatal diagnosis.
In conclusion, it is important to diagnose this disorder as both treatment and prenatal diagnosis are possible.
References
1. Mitchell GA, Grompe M, Lambert M, Tanguay RM. Hypertyrosinemia. In Scriver CR, Beaudet AL, Sly WS and Valle D, eds. The Metabolic and Molecular Bases of Inherited Disease. 8th edn. New York; McGraw-Hill Co, 2001: 1777-1806.
2. De Braekeleer M, Larochelle J. Genetic epidemiology of hereditary tyrosinemia in Quebec and in Saguenay-Lac-St-Jean. Am J Hum Genet 1990; 47: 302-307.
3. Halvorsen S. Screening for disorders of tyrosine metabolism. In Bicke H, Guthrie R, Hammerson G, eds. Neonatal screening for inborn errors of metabolism. New York; Springer-Verlag, 1980: 45.
4. Appaji Rao N, Radha Rama Devi A, Savithri HS, Venkat Rao S, Bittles AH. Neonatal screening for aminoacidemias in Karnataka, South India. Clin Genet 1988; 34: 60-63.
5. Verma IC. Burden of genetic disorders in India. Indian J Pediatr 2000; 67 : 893-898.
6. Karnik D, Thomas N, Eapen CE, Jana AK, Oommen A. Tyrosinemia type I: A clinico-laboratory case report. Indian J Pediatr 2004; 10: 929-932.
7. Grenier A, Lescault A, Laberge C, Gagnι R, Mamer O. Detection of succinylacetone and the use of its measurement in mass screening for hereditary tyrosinemia. Clin Chim Acta 1982; 123: 93-99.
8. Laberge C, Grenier A, Valet JP, Morissette J. Fumarylacetotase measurement as a mass-screening procedure for hereditary tyrosinemia type I. Am J Hum Genet 1990; 47 : 325-328.
9. McCormack MJ, Walker E, Gray RG, Newton JR, Green A. Fumarylacetoacetase activity in cultured and non-cultured chorionic villus cells, and assay in two high-risk pregnancies. Prenat Diagn. 1992; 12 : 807-813.
10. Kvittingen EA. Hereditary tyrosinemia type I- an overview. Scand J Clin Lab Invest Suppl 1986; 184 : 27-34.
11. Sakai K, Kitagawa T. An atypical case of tyrosinosis (1-para-hydroxyphyenyllactic aciduria): I. Clinical and laboratory findings. Jikei Med J 1957; 2: 1.
12. Rezvani I. Defects in metabolism of amino acids. In: Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 17th edn. Philadelphia; Saunders, 2004: 402-403.
13. Heath SK, Gray R G F, McKiernan P, Au K M, Walker E and Green A. Mutation screening for tyrosinaemia type I. J Inherit Metab Dis 2002; 24: 523-4.
14. Gagne R, Lescault A, Grenier A, Laberge C, Melancon S B, Dallaire L. Prenatal diagnosis of hereditary tyrosinaemia: measurement of succinylacetone in amniotic fluid. Prenatal Diag 1982; 2: 185-188.
15. Kvittingen E A, Halvorsen S, Jellum E. Deficient fumarylacetoacetate fumarylhydrolase activity in lymphocytes and fibroblasts from patients with hereditary tyrosinemia. Pediat Res 1983; 17: 541-544.(Bijarnia Sunita, Puri Rat)
2 Biochimiste Clinique Laboratoire de Genetique CHUQ Pavillon CHUL 2705, Boul. Laurier Sainte-Foy, Quebec, Canada
3 Clinical Chemistry, Birmingham Children's Hospital, Birmingham, United Kingdom
Abstract
A fifteen-month-old boy, born to consanguineously married couple, presented with asymptomatic hepatomegaly. Investigations revealed mildly deranged liver functions, necroinflammatory changes and cirrhosis on liver biopsy, a markedly raised alpha feto protein and tyrosine levels in plasma and a generalized aminoaciduria. His diagnosis of hereditary tyrosinemia was established on findings of raised serum and urine succinylacetone, and a deficient activity of fumaryl acetoacetate hydroxylase enzyme. Prenatal diagnosis of hereditary tyrosinemia was performed in a subsequent pregnancy in this family from India.
Keywords: Tyrosinemia type 1; Fumaryl acetoacetate hydroxylase enzyme; Prenatal diagnosis
Tyrosinemia type I (hepatorenal tyrosinemia, OMIM No. 276700) is a rare autosomal recessive disorder, with clinical and pathological manifestations involving mainly the liver, kidney, and peripheral nerves.[1] The clinical findings range from severe hepatocellular dysfunction in early infancy to chronic liver disease. The disorder is common in Quebec (1 in 16,786 live births) and Scandinavia, with a worldwide incidence of 1/100,000 to 1/120,000 population.[2],[3] There have been few reports from India although none has been based on enzyme assay and succinylacetone levels, which are confirmatory for diagnosis. [4],[5],[6] We present a case confirmed with enzyme assay, and report prenatal diagnosis of tyrosinemia in the mother of the index case.
Case Report
A fifteen-month-old boy was referred for evaluation in view of persistent hepatomegaly. He was born to a consanguineously married couple (uncle - niece marriage) and was the only child. The antenatal and perinatal periods were uneventful. He came to medical attention at six months of age, when the family pediatrician noted him to have hepatomegaly on a routine check-up. At eight months of age there was an episode of fever, with constipation during which he had a typical febrile seizure. There were no other symptoms. He was gaining all milestones appropriately for age. The child was immunized for age including for Hepatitis A and B. Dietary history was largely adequate in calories and proteins, except for history of loss of appetite, off and on. The illness remained static from identification at 6 months to presentation at 15 months.
Examination revealed a healthy looking child with weight of 13 kg and height 82 cm (normal for age). General physical examination was unremarkable with no dysmorphic facies. The child had a firm hepatomegaly,
3-cm below the costal margin in midclavicular line. The spleen was not palpable. There was no free fluid in the abdomen. Examination of cardiovascular, respiratory and central nervous system revealed no abnormality.
The investigations performed were as follows: hemoglobin 10.1 gm/dl, total leukocyte count 10,700 /cu.mm, differential count neutrophils 34%, lymphocytes 60%, monocytes 04%, and eosinophils 02%, peripheral smear - predominantly microcytic hypochromic cells with target cells, RBC indices suggestive of beta - thalassemia trait and blood sugar 60 mg/dl. Renal functions (BUN and creatinine) and serum electrolytes were normal. Liver function tests showed mild derangement; prothrombin time was 14.2 sec (control 12 seconds). There was mild derangement in liver enzymes with SGOT of 58 and SGPT of 108 IU/ml. Urine reducing substances were negative; there was generalized aminoaciduria on thin layer chromatography, and plasma tyrosine measured by HPLC was raised (3340 micromol/liter, normal range 7-127).
An ultrasound study of the abdomen revealed multiple hypoechoic lesions in both lobes of liver (upto 9 mm) and mild splenomegaly, both kidneys were normal in size and echotexture. CT scan abdomen corroborated the findings of ultrasound. MRI showed diffuse hepatic parenchymal disorder with micronodular lesions suggestive of cirrhosis of liver with regenerating nodules. Liver biopsy showed cores of liver tissue dissected by thin bridging fibrous septa into small nodules amounting to established cirrhosis. There was macrovesicular steatosis affecting about 50% of hepatocytes. There was no definite evidence of storage disorder, and necroinflammatory activity was noted raising a suspicion of tyrosinemia. Bone marrow aspiration showed normal results. The serum alpha feto protein (AFP) was markedly raised (41050 ng/ml); and there was a normal level of sphingomyelinase enzyme (0.79 nmol/hour/ mg of protein) and serum alpha-1-anti-trypsin levels (3950 mg/L). Blood succinyl acetone, measured indirectly by its inhibition of porphobilinogen synthase-delta-aminolevulinate dehydratase reaction,[7] was 9.0 micromol/L (normal <2.5), and urine succinyl acetone was 4.5 micromol/L (normal < 1). Enzyme fumaryl acetoacetate hydroxylase (FAH), measured by ELISA, using a specific anti-human FAH antibody[8], was abnormal with <5% of normal control activity noted on two occasions on two blood spots. These results confirmed the diagnosis of hereditary tyrosinemia type 1 (HT1). Therapy with 2-(nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC) was advised. The family was provided genetic counseling and explained the inheritance with 25% risk of recurrence in a future pregnancy, and informed that prenatal diagnosis would be possible.
The family consulted us during pregnancy for a prenatal diagnosis of HT1. Initial gene studies for the 4 common mutations (G192T, IVS12t 5G>A, IVS 6_1G>T and 1009G>A) reported among Indians and Pakistanis in the United Kingdom[9] were negative. At 12 weeks pregnancy, chorionic villous sampling (CVS) was carried out and the cleaned CV was then shipped to Birmingham in dry ice. FAH enzyme assay was performed on the CV sample. The result revealed a normal activity of FAH enzyme in uncultured CV (1.57) as compared to value in control of 1.50, the normal range of the enzyme in the CVS being 1.07 - 2.98, and the range for affected fetus <0.45.[10] These results excluded an affected fetus with HT1.
Discussion
Hepatorenal tyrosinemia HT1 (OMIM 276700) is a clinically severe inborn error that principally affects liver, kidney, and peripheral nerve.[1] It is one of the best-documented inborn errors of metabolism and has the highest incidence of developing hepatocellular carcinoma in the chronic form.[11] The first case of typical clinical and biochemical picture of hepatorenal tyrosinemia was described by Sakai et al in 1957.[12] Since then, there have been over 100 case reports appearing in literature. Reports from the Indian subcontinent are few and without enzyme assay.[4],[5],[6] HT1 is commonly suspected in India[4] but is under-diagnosed due to lack of availability of confirmatory tests.
The disease typically manifests in early infancy with acute hepatic crisis with hepatomegaly and bleeding diathesis precipitated by intercurrent illnesses inducing a catabolic state.[13] The acute crisis may resolve spontaneously but usually persists as hepatomegaly, coagulation abnormalities and failure to thrive. Cirrhosis of liver, hepatocellular carcinoma and death eventually occur early in life. Other features of tyrosinemia are peripheral neuropathy resembling acute porphyria and renal manifestations.[13]
The diagnosis in this patient is based on persistent asymptomatic firm hepatomegaly, a mildly deranged liver functions, very high AFP levels, high tyrosine levels in plasma with urinary aminoaciduria, liver findings of macrovesicular steatosis, micronodular lesions suggestive of cirrhosis with necro-inflammatory changes on liver biopsy. Raised plasma and urine succinylacetone levels and a deficient enzyme activity of FAH further confirmed the diagnosis and a pre-requisite for a subsequent prenatal diagnosis.[9]
Molecular diagnosis is possible and is the preferred technique for prenatal diagnosis. FAH gene is located on chromosome 15 q and has 14 exons.[1] Since the first report of the missense mutation n161 in the FAH mRNA, many mutations have been identified causing the disease.[1] Of these, there are 4 common mutations observed in subjects from the Indian Subcontinent.[9]
Liver transplant is curative for the disorder, and prior to NTBC it was the mainstay of therapy. NTBC has revolutionized the therapy as it is effective within hours and abolishes or markedly diminishes the risk of hepatic or neurologic decompensation.[1] Major issues regarding NTBC is confirmation of diagnosis, difficulties in import, and the cost involved.
Prenatal diagnosis (PND) can be performed using three techniques. The first report of prenatal diagnosis of HT1 was by measuring succinylacetone in amniotic fluid in 1982[14] and is still being used. Second method of PND is by enzyme assay (FAH) in chorionic villi taken at 10-12 weeks of gestation.[15] PND by molecular technology is the most accurate method in cases where the mutations are known in the FAH gene. The concerned family was tested using the enzyme assay method as no mutations could be identified in the short time period available between the diagnosis of the child with disease and prenatal diagnosis.
In conclusion, it is important to diagnose this disorder as both treatment and prenatal diagnosis are possible.
References
1. Mitchell GA, Grompe M, Lambert M, Tanguay RM. Hypertyrosinemia. In Scriver CR, Beaudet AL, Sly WS and Valle D, eds. The Metabolic and Molecular Bases of Inherited Disease. 8th edn. New York; McGraw-Hill Co, 2001: 1777-1806.
2. De Braekeleer M, Larochelle J. Genetic epidemiology of hereditary tyrosinemia in Quebec and in Saguenay-Lac-St-Jean. Am J Hum Genet 1990; 47: 302-307.
3. Halvorsen S. Screening for disorders of tyrosine metabolism. In Bicke H, Guthrie R, Hammerson G, eds. Neonatal screening for inborn errors of metabolism. New York; Springer-Verlag, 1980: 45.
4. Appaji Rao N, Radha Rama Devi A, Savithri HS, Venkat Rao S, Bittles AH. Neonatal screening for aminoacidemias in Karnataka, South India. Clin Genet 1988; 34: 60-63.
5. Verma IC. Burden of genetic disorders in India. Indian J Pediatr 2000; 67 : 893-898.
6. Karnik D, Thomas N, Eapen CE, Jana AK, Oommen A. Tyrosinemia type I: A clinico-laboratory case report. Indian J Pediatr 2004; 10: 929-932.
7. Grenier A, Lescault A, Laberge C, Gagnι R, Mamer O. Detection of succinylacetone and the use of its measurement in mass screening for hereditary tyrosinemia. Clin Chim Acta 1982; 123: 93-99.
8. Laberge C, Grenier A, Valet JP, Morissette J. Fumarylacetotase measurement as a mass-screening procedure for hereditary tyrosinemia type I. Am J Hum Genet 1990; 47 : 325-328.
9. McCormack MJ, Walker E, Gray RG, Newton JR, Green A. Fumarylacetoacetase activity in cultured and non-cultured chorionic villus cells, and assay in two high-risk pregnancies. Prenat Diagn. 1992; 12 : 807-813.
10. Kvittingen EA. Hereditary tyrosinemia type I- an overview. Scand J Clin Lab Invest Suppl 1986; 184 : 27-34.
11. Sakai K, Kitagawa T. An atypical case of tyrosinosis (1-para-hydroxyphyenyllactic aciduria): I. Clinical and laboratory findings. Jikei Med J 1957; 2: 1.
12. Rezvani I. Defects in metabolism of amino acids. In: Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 17th edn. Philadelphia; Saunders, 2004: 402-403.
13. Heath SK, Gray R G F, McKiernan P, Au K M, Walker E and Green A. Mutation screening for tyrosinaemia type I. J Inherit Metab Dis 2002; 24: 523-4.
14. Gagne R, Lescault A, Grenier A, Laberge C, Melancon S B, Dallaire L. Prenatal diagnosis of hereditary tyrosinaemia: measurement of succinylacetone in amniotic fluid. Prenatal Diag 1982; 2: 185-188.
15. Kvittingen E A, Halvorsen S, Jellum E. Deficient fumarylacetoacetate fumarylhydrolase activity in lymphocytes and fibroblasts from patients with hereditary tyrosinemia. Pediat Res 1983; 17: 541-544.(Bijarnia Sunita, Puri Rat)