[Mitochondrial 2-methylacetoacetyl-CoA thiolase deficiency in Argentina]. / Deficiencia de la 2-metilacetoacetil-CoA tiolasa mitocondrial en Argentina.

From the description of two pairs of siblings belonging to unrelated families, one Argentine family with a history of consanguinity and Irish ancestry and the other family native of Paraguay, in whom mitochondrial 2-methylacetoacetyl-CoA thiolase deficiency, commonly known as beta-ketothiolase deficiency (beta-KTD, McKusick 203750; EC 2.3.1.9) was recognized. We tried to outline through this experience the clinical and biochemical consequences of this genetic defect in the 6th step of the isoleucine catabolism. The phenotyoic expression presented by the patients belonged to the classical form of beta-KTD. Seven to 15 months was the age at onset of the uniform clinical pattern this being essentially an association of one or several severe ketoacidotic episodes and hyperglycemia which was observed in two patients. The thin-layer chromatography of the tiglylglycine, and dinitrophenylhydrazone of the butanone were positive; aminoacidemia and aminoaciduria revealed normal levels. The organic acids having a unique profile obtained through gaschromatography and mass-spectrometry (GC/MS) showed excretion of large quantities of metabolites characteristic of the disease: 2-methyl-3-hydroxybutirate, 2-methylacetoacetic acid, tiglylglycine and 2-ethylhydracrilic acid which led us to establish the biochemical diagnosis of beta-KTD. The assay of the beta-ketothiolase in lymphocytes and polymorphonuclear leukocytes of the only surviving patient (VT) showed absence of activation by the K+ ion when the acetoacetyl-CoA was used as a substrate. This first Argentine report about beta-KTD leads us to mention three amplifying aspects with regards to previous literature: it adds other different ethnic ancestries of patients, points out a morphological analysis of autopsy material with unchanged structures in the brain, liver and kidneys and marks in the patient VT a dissociation between a symptom-free clinical pattern since age 7 and the persistent biochemical abnormality until the present age, 15 years. The knowledge of the existence of these diseases in our country together with the availability and access to GC/MS of high precision and speed, will allow early diagnosis and better therapeutic results.

[Hepatic glycogen synthetase deficiency or glycogen storage disease-zero. Mild phenotype with partial enzymatic defect]. / Deficiencia en glucógeno sintetasa hepática o glucogenosis tipo cero. Fenotipo menos severo con defecto enzimático parcial.

Since the original description 26 years ago, of the hepatic glycogen synthetase deficiency, only one more case was reported in 1977. We present the studies carried out on an Argentine boy of Italian ancestry who at age 21 months, showed signs of hepatic deficiency with mild clinical symptoms which contrasted with a remarkable fatty liver degeneration. A totally atypic reaction to fructose overload (Table 1, Fig. 1) was the first key to the diagnosis. Glucose levels were not significantly modified by glucagon after 12-hours fasting, but it did increase the glycemia, with decrease of lactate and alanine 3 hours after-meal (Fig. 2a, b). The 24-hours metabolic profile showed fasting hypoglycemia, hyperketonemia, low alanine concentrations and mild lactatemia and hyperglycemia and a net post-prandial increase of lactate (Fig. 3). This profile when reduced to 14 hours, 12-fasting hours and 2-postprandial hours (Fig. 4), revealed similar alterations in an asymptomatic younger brother. The development of the investigation led to a second hepatic biopsy which confirmed hepatic steatosis and to an ultrastructural study, which showed subcellular alterations in the liver and also in muscle (Fig. 5). Moreover low content of hepatic glycogen was observed along with glycogen synthetase activity between 20-25% that of controls, being normal the enzyme activity in muscle and fibroblasts cultured from a skin biopsy (Table 2). The clinical pattern mainly without hypoglycemia, convulsions and/or mental retardation and a normal height and body mass development, allowed us to postulate that this Argentine report would be a mild variant of the disease formerly described and would be correlated with a partial deficiency of the hepatic glycogen synthetase.

Deficiencia en glucógeno sintetasa hepática o glucogenosis tipo cero. Fenotipo menos severo con defecto enzimático parcial. / [Hepatic glycogen synthetase deficiency or glycogen storage disease-zero. Mild phenotype with partial enzymatic defect]

Since the original description 26 years ago, of the hepatic glycogen synthetase deficiency, only one more case was reported in 1977. We present the studies carried out on an Argentine boy of Italian ancestry who at age 21 months, showed signs of hepatic deficiency with mild clinical symptoms which contrasted with a remarkable fatty liver degeneration. A totally atypic reaction to fructose overload (Table 1, Fig. 1) was the first key to the diagnosis. Glucose levels were not significantly modified by glucagon after 12-hours fasting, but it did increase the glycemia, with decrease of lactate and alanine 3 hours after-meal (Fig. 2a, b). The 24-hours metabolic profile showed fasting hypoglycemia, hyperketonemia, low alanine concentrations and mild lactatemia and hyperglycemia and a net post-prandial increase of lactate (Fig. 3). This profile when reduced to 14 hours, 12-fasting hours and 2-postprandial hours (Fig. 4), revealed similar alterations in an asymptomatic younger brother. The development of the investigation led to a second hepatic biopsy which confirmed hepatic steatosis and to an ultrastructural study, which showed subcellular alterations in the liver and also in muscle (Fig. 5). Moreover low content of hepatic glycogen was observed along with glycogen synthetase activity between 20-25

that of controls, being normal the enzyme activity in muscle and fibroblasts cultured from a skin biopsy (Table 2). The clinical pattern mainly without hypoglycemia, convulsions and/or mental retardation and a normal height and body mass development, allowed us to postulate that this Argentine report would be a mild variant of the disease formerly described and would be correlated with a partial deficiency of the hepatic glycogen synthetase.