First reported case of prenatal diagnosis for pyruvate kinase deficiency in a Chinese family

We describe the first case of prenatal diagnosis for pyruvate kinase (PK) deficiency in Chinese and emphasize that this disease is an important differential diagnosis in pediatric patients with non-spherocytic hemolytic anemia. A Han Chinese child with a history of severe transfusion-dependent hemolytic anemia was diagnosed to have PK deficiency. Prenatal diagnosis was performed on the second child based on the genetic findings from the family. The index patient was compound heterozygous for a missense mutation (c.1073G > A. p.Gly358Glu) from his father and a large deletion (c.283 + 1914_c.1434del5006) from his mother. The fetus was a simple heterozygote for the paternal mutation. Pregnancy was allowed to continue and a healthy baby was born. Severe PK deficiency warranting prenatal diagnosis is seen in Han Chinese. Genetic characterization and genotype-phenotype correlation studies on PKLR in different populations are indicated to better define the role of prenatal diagnosis in PK deficiency.     

First reported case of prenatal diagnosis for pyruvate kinase deficiency in a Chinese family

Abstract

We describe the first case of prenatal diagnosis for pyruvate kinase (PK) deficiency in Chinese and emphasize that this disease is an important differential diagnosis in pediatric patients with non-spherocytic hemolytic anemia. A Han Chinese child with a history of severe transfusion-dependent hemolytic anemia was diagnosed to have PK deficiency. Prenatal diagnosis was performed on the second child based on the genetic findings from the family. The index patient was compound heterozygous for a missense mutation (c.1073G>A. p.Gly358Glu) from his father and a large deletion (c.283+1914_c.1434del5006) from his mother. The fetus was a simple heterozygote for the paternal mutation. Pregnancy was allowed to continue and a healthy baby was born. Severe PK deficiency warranting prenatal diagnosis is seen in Han Chinese. Genetic characterization and genotype–phenotype correlation studies on PKLR in different populations are indicated to better define the role of prenatal diagnosis in PK deficiency.     

Lactic acidosis due to pyruvate carboxylase deficiency

Two unrelated Canadian Indian infants presented with metabolic acidosis. Lactate, pyruvate, glutamic acid, proline and alanine were greatly elevated in plasma. Urinary excretion of -ketoglutarate and pyruvate was increased. Pyruvate carboxylase activity was very low in skin fibroblasts and liver. Phosphoenolpyruvate carboxykinase was low in liver. Both infants were unresponsive to several enzyme cofactors, including biotin. Both survive at age 2 years with severe mental retardation.     

Lactic acidosis due to pyruvate carboxylase deficiency

Two unrelated Canadian Indian infants presented with metabolic acidosis. Lactate, pyruvate, glutamic acid, proline and alanine were greatly elevated in plasma. Urinary excretion of alpha-ketoglutarate and pyruvate was increased. Pyruvate carboxylase activity was very low in skin fibroblasts and liver. Phosphoenolpyruvate carboxykinase was low in liver. Both infants were unresponsive to several enzyme cofactors, including biotin. Both survive at age 2 years with severe mental retardation..     

Neonatal pyruvate carboxylase deficiency with renal tubular acidosis and cystinuria

This report concerns a patient with severe congenital lacticacidosis associated with proximal renal tubular acidosis and cystinuria. Enzyme studies with cultured skin fibroblasts obtained from the patient revealed zero pyruvate carboxylase activity, but propionyl-CoA carboxylase activity was normal. Administration of various vitamins in large amounts did not improve the clinical condition. In contrast, the patient began to thrive when her diet was supplemented with aspartic acid, asparagine, glutamic acid, and glutamine. The particular dietary treatment used and the biochemical findings merit consideration for management of future cases.     

Brain amino acid abnormalities in pyruvate carboxylase deficiency

Amino acids were measured in several regions of autopsied brain from an infant who died with congenital lactic acidosis due to pyruvate carboxylase deficiency (McKusick 26615), as well as in cerebrospinal fluid (CSF) and plasma of four living infants with this disorder. Glutamine content was greatly reduced in all brain regions, while glutamic acid and proline contents were elevated. The -aminobutyric acid (GABA) content was normal in brain. Glutamine concentrations in CSF and plasma were also decreased in the living patients. Glutamine may serve as a pool to provide glutamate and GABA for use as neurotransmitters, and to provide -ketoglutarate for the tricarboxylic acid cycle when oxaloacetate can no longer be formed directly from pyruvate.     

The clinical and biochemical implications of pyruvate carboxylase deficiency.

A 10 month old female infant was evaluated for severe lactic acidosis. Clinically she was well nourished and had a substantial amount of adipose tissue despite recurrent episodes of acidosis. Her psychomotor development was retarded, her movements were dystonic and generalized seizures punctuated her course. Metabolic abnormalities included elevated blood concentrations of lactate, pyruvate, beta-hydroxybutyrate, acetoacetate, alanine, proline and glycine, decreased blood concentrations of glutamine, aspartate, valine and citrate, and intermittent elevations of serum cholesterol. A trial on a high-fat diet worsened the clinical condition and intensified the ketoacidosis and hyperalaninemia. Analysis of hepatic tissue obtained by open biopsy revealed increased concentrations of lactate, alanine, acetyl-CoA and other short-chain acyl-CoA esters, and decreased concentrations of oxaloacetate, citrate, alpha-ketoglutarate, malate and aspartate. The blood and tissue metabolic perturbations reflected a deficiency of hepatic pyruvate carboxylase. The apparent Km of hepatic citrate synthase for oxaloacetate was 4.6 micrometer. Calculated tissue oxaloacetate concentrations were 0.50--0.84 micrometer suggesting that tricarboxylic acid cycle activity was severely limited by the decreased availability of this substrate. An iv glucose tolerance test resulted in the paradoxical synthesis of ketone bodies. This observation, coupled with the intermittent hypercholesterolemia and the increased tissue acetyl-CoA concentrations, suggests that pyruvate carboxylase is important in modulating the fractional distribution of intracellular acetyl-CoA between the tricarboxylic acid cycle, the beta-hydroxy-beta-methyl-glutaryl-CoA cycle (and the synthesis of cholesterol and ketone bodies), and fatty acid synthesis. Treatment in future cases might be directed toward increasing tissue concentrations of oxaloacetate.     

Prenatal diagnosis of pyruvate kinase deficiency

Prenatal testing for pyruvate kinase deficiency is often requested by parents who already have an affected child. However, before the development of molecular biologic techniques there were no suitable diagnostic methods. We present here two cases in which the diagnosis was established, one using amniotic fluid cells, the other cord blood. Two different approaches were used. The first, using a direct method of PCR amplification and restriction endonuclease analysis, detected mutations in fetus genomic DNA. The second method, using two polymorphic sites linked to the PKRL gene, enabled us to establish which chromosome had been inherited from each parent.     

Amino acid profile in pyruvate carboxylase deficiency: Comparison with some other metabolic disorders

Four cases of variant hyperphenylalaninaemia during pregnancy are presented. Babies born to mothers with blood phenylalanine concentrations of 4–8 mg/dl were normal and did not exhibit significant microcephaly, although one did have a major congenital anomaly (exstrophy of the bladder). The mother with blood phenylalanine concentrations of 6–12 mg/dl during pregnancy delivered three of four infants with mild microcephaly but normal intellectual function. The data suggest that phenylalanine concentrations of 4–8 mg/dl are reasonable and desirable during pregnancy in hyperphenylalaninaemic women. Furthermore, the data do not support or refute the justification hypothesis of Bessmanet al.     

Leigh's disease with decreased activities of pyruvate carboxylase and pyruvate decarboxylase

In a patient with the clinical symptoms of Leigh's disease a partial deficiency of hepatic pyruvate carboxylase and pyruvate decarboxylase was found at necropsy. Cerebral pyruvate decarboxylase activity was also diminished. All enzyme activities were measured in total homogenates. The finding of typical necrotic lesions in the brain stem was consistent with the clinical diagnosis. During life moderate lactic acidaemia and no hypoglycaemia were observed, but an abnormal organic acid excretion pattern was present. The contribution of the enzyme defects to the aetiology of the disease is discussed.     

Neonatal lactic acidosis with pyruvate carboxylase inactivity

Biochemical findings in a case of acute onset lactic acidosis due to pyruvate carboxylase deficiency are presented. Oxaloacetate deficiency arising from the inactivity of pyruvate carboxylase produces abnormal cytosolic and mitochondrial redox states. The resultant altered metabolite pattern may allow a provisional diagnosis before enzymatic studies.     

Successful hematopoietic stem cell transplantation for Fanconi anemia from an unaffected HLA-genotype-identical sibling selected using preimplantation genetic diagnosis

The only proven cure for Fanconi anemia (FA)-associated bone marrow failure is successful allogeneic hematopoietic stem cell transplantation (HSCT). However, HSCT with donors other than HLA-identical siblings is associated with high morbidity and poor survival. Therefore, we used preimplantation genetic diagnosis (PGD) to select an embryo produced by in vitro fertilization (IVF) that was unaffected by FA and was HLA-identical to the proband. The patient was a 6-year-old girl with FA and myelodysplasia previously treated with oxymetholone and prednisone. After her parents underwent 5 cycles of IVF with intrauterine transfer of 7 embryos over a span of 4 years, successful pregnancy ensued. Twenty-eight days after delivery, the patient underwent transplantation with her newborn sibling donor's HLA-identical umbilical cord blood hematopoietic stem cells (HSCs). Neutrophil recovery occurred on day 17 without subsequent acute or chronic graft-versus-host disease. Currently, 2.5 years after transplantation, the patient is well and hematopoiesis is normal. In summary, we have described the first successful transplantation, using IVF and PGD, of HSCs from a donor selected on the basis of specific, desirable disease and HLA characteristics. The medical, legal, and ethical issues involved with this approach are discussed.     

Disorders of pyruvate carboxylase and the pyruvate dehydrogenase complex

Summary The most common defect associated with deficiency of the pyruvate dehydrogenase (PDH) complex occurs in the E₁ component, specifically due to mutations in the X-linked E₁ gene. Clinical sequelae of these mutations, which range from severe neonatal lactic acidosis to carbohydrate-sensitive ataxia, can be different in males and females depending on the nature of the mutation and, in the case of females, on the X-inactivation pattern in different tissues. Males have a high representation of missense mutations among the patient cohort, while females are much more likely to have DNA rearrangements, particularly toward the 3 end of the coding sequence of the gene. Missplicing mutations involving exon 6 deletion have been reported, as has a missense mutation conferring true thiamin-responsiveness of the enzyme and the patient's clinical symptoms.Pyruvate carboxylase deficiency, on the other hand, is a true autosomal recessive disease, though it has high occurrences in particular ethnic groups, especially in Algonkian-speaking Amerindians and in Arabs. In the former group the defect is a simple type in which material cross-reactive to pyruvate carboxylase antibody is present in cultured cells (CRM^+ve). In the latter group, cross-reacting material is rarely present (CRM^–ve). The CRM^+ve patients can survive into teenage years with careful supervision, while the CRM^–ve patients have complications due to hyperammonaemia and dysfunction of the urea cycle and rarely survive beyond 3 months of life.