1/26. Long-term follow up of a new case of hawkinsinuria. Hawkinsinuria is a rarely diagnosed autosomal dominantly transmitted inborn error of tyrosine metabolism with impaired conversion of 4-hydroxyphenylpyruvate to homogentisate. As a consequence of the defective 4-hydroxyphenylpyruvate dioxigenase activity, large amounts of the unusual, ninhydrin-positive amino acid hawkinsin and later on in life 4-hydroxycyclohexylacetic acid are formed and excreted. Clinically the disease is characterised mainly by chronic metabolic acidosis and severe growth retardation as a result of protein overload. As the ability to form 4-hydroxycyclohexylacetic acid and thereby to cope with the still not very well defined reactive and toxic intermediates increases, clinical symptoms vanish. We report here a new patient with hawkinsinuria having experienced a series of admissions because of unclear hepatopathy, growth retardation, and renal tubular acidosis. CONCLUSION: Prolonged tyrosyluria in the newborn and young baby should cause the clinical chemist not only to exclude tyrosinaemia, galactosaemia, and fructose intolerance but also to look carefully for hawkinsin in the aminoacid chromatogram. ( info) |
2/26. Hereditary fructose intolerance and alpha(1) antitrypsin deficiency. A patient with coexisting hereditary fructose intolerance (HFI) and alpha(1) antitrypsin deficiency (alpha(1)ATD) is described. Protease inhibitor typing was not conclusive, presumably because of impaired N-glycosylation secondary to HFI. The case underlines the diagnostic role of molecular genetic techniques in inborn errors of metabolism. ( info) |
3/26. Hereditary fructose intolerance presenting as Reye's-like syndrome: report of one case. Hereditary fructose intolerance (HFI) is an autosomal recessive disease caused by catalytic deficiency of aldolase B (fructose-1, 6-bisphosphate aldolase). Herein we report on a case of hereditary fructose intolerance with initial presentation of episodic unconsciousness, seizure, hypoglycemia, hepatomegaly, and abnormal liver function since the patient was 11 months old. She was diagnosed as Reye's-like syndrome according to a liver biopsy done at 20 months of age. As she grew up, cold sweating, abdominal pain or gastrointestinal discomfort shortly after the intake of fruits was noted and she developed an aversion to fruits, vegetables and sweet-tasting foods. At 9 years of age, a fructose tolerance test signified a positive result that induced hypoglycemia, transient hypophosphatemia, hyperuricaemia, elevation of serum magnesium, and accumulation of lactic acid. Appropriate dietary management and precautions were recommended. The patient has been symptom-free and exhibited normal growth and development when followed up to 12 years of age. ( info) |
4/26. Simple method for detection of mutations causing hereditary fructose intolerance. Aldolase B is critical for sugar metabolism, and a catalytic deficiency due to mutations in its gene may result in hereditary fructose intolerance (HFI) syndrome, with hypoglycaemia and severe abdominal symptoms. This report describes two cases of HFI, which were identified by intravenous fructose tolerance test and a new RFLP (restriction fragment length polymorphism) test that detects the two most common mutations, A149P and A174D. The method includes PCR of a 224-base-pair segment of exon 5, a subsequent 3 h incubation with Cac8I and agarose electrophoresis, which reveals either or both of the mutations in one single reaction. The method might be useful for screening of these mutations, which may account for more than 70% of the mutations causing HFI. ( info) |
5/26. Studies of glucose turnover and renal function in an unusual case of hereditary fructose intolerance. Examination of glucose kinetics, pancreatic alpha and beta cell function, plasma lipids, urinary acidification and calcium excretion has been undertaken in a patient with hereditary fructose intolerance. This case was unusual as it was associated with insulin-requiring diabetes, type IV hyperlipemia, hypercalciuria and renal calculi. He also demonstrated the previously described fructose-induced defect of urine acidification. glucagon and c-peptide assays showed that the pancreatic alpha cells were stimulated by fructose and that the beta cells did not respond to fructose. It is not known whether the latter was due to his diabetes or to the lack of a beta cell response to this sugar. Primed 14C-glucose infusions were used for the first time to study nonsteady state glucose kinetics in man. They showed that, 24 hours after the last insulin injection and under basal conditions, the glucose concentrations increased because glucose production exceeded glucose utilization. However, after the administration of sorbitol the plasma glucose concentration decreased because glucose production decreased. After the administration of sorbitol there was no change in the metabolic clearance of glucose. This reflects the lack of a peripheral insulin effect and is consistent with the lack of any measurable c-peptide. Glucose utilization also decreased, but this decrease was less than the decrease in glucose production. Because the metabolic clearance of glucose remained unchanged, it was concluded that the change in glucose utilization was solely due to the decrease in glucose concentration. The absence of c-peptide in the plasma indicated that changes in glucose turnover were not related to any changes in endogenous plasma insulin. Furthermore, the plasma glucagon concentration increased and, hence, changes in this hormone could not account for the decrease in glucose production. Therefore, it was concluded that the sorbitol-induced decline in glucose production was due to a direct effect on hepatic metabolism. ( info) |
6/26. Fructose breath hydrogen test--is it really a harmless diagnostic procedure? Usage of hydrogen breath tests has become one of the standard procedures in diagnosing chronic unspecific abdominal pain. These tests are said to be of sufficient specificity and sensitivity, are easily done, non-invasive and are more often practiced in outpatients. A 13-year-old boy is reported with chronic unspecific abdominal pain and growth retardation and so far misdiagnosed hereditary fructose intolerance (HFI), who developed life-threatening adverse effects during the fructose breath hydrogen test. It is concluded that the possibility of HFI should be excluded first by a carefully explored dietary history before the fructose breath test is performed under medical supervision. If there is any suspicion of HFI, a molecular genetic analysis should be preferred. ( info) |
7/26. Six novel alleles identified in Italian hereditary fructose intolerance patients enlarge the mutation spectrum of the aldolase B gene. Hereditary fructose intolerance (HFI) is a recessively inherited disorder of carbohydrate metabolism caused by impaired functioning of human liver aldolase (B isoform; ALDOB). To-date, 29 enzyme-impairing mutations have been identified in the aldolase B gene. Here we report six novel HFI single nucleotide changes identified by sequence analysis in the aldolase B gene. Three of these are missense mutations (g.6846T>C, g.10236G>T, g.10258T>C), one is a nonsense mutation (g.8187C>T) and two affect splicing sites (g.8180G>C and g.10196A>G). We have expressed in bacterial cells the recombinant proteins corresponding to the g.6846T>C (p.I74T), g.10236G>T (p.V222F), and g.10258T>C (p.L229P) natural mutants to study their effect on aldolase B function and structure. All the new variants were insoluble; molecular graphics data suggest this is due to impaired folding. ( info) |
8/26. Case report: heterogeneity of aldolase B in hereditary fructose intolerance. Hereditary fructose intolerance (HFI) is a recessive genetic disorder with an estimated disease frequency of 1 in 20,000 and a carrier frequency of 1 in 70. Affected individuals are unable to assimilate fructose from fruit sugars and may develop severe hypoglycemia, metabolic problems, and death if misdiagnosed. Those who survive childhood learn to avoid sweets, effectively preventing further symptoms and complications. The disease is caused by a genetically defective hepatic enzyme, aldolase B. Traditionally, diagnosis has been made by intravenous fructose challenge or by liver biopsy, both difficult and risky invasive tests. Identification of mutations of the aldolase B gene by analysis of dna from blood leukocytes is now possible, allowing for potential noninvasive diagnosis of subjects at risk in the future. The authors demonstrate heterozygosity for an aldolase B gene mutation in a patient with HFI. ( info) |
9/26. Hereditary fructose intolerance in a patient with phenylketonuria. Classical phenylketonuria (PKU) and hereditary fructose intolerance (HFI) are two inborn errors of metabolism that have an autosomal recessive mode of inheritance. In this paper, we described a 3-year-old girl with PKU and HFI. The occurrence of these two defects in the same patient is thought to be fortuitous and not genetically related since this is the first reported case and the statistical probability of such an occurrence is very low. ( info) |
| A girl aged 3 years and 11 months, with recurrent episodes of unexplained metabolic acidosis, hepatomegaly, and fasting hypoglycemia unresponsive to glucagon, showed profound falls in blood glucose levels in response to oral fructose and glycerol challenge. in vitro analysis of her hepatic glycolytic and gluconeogenic enzymes demonstrated absent fructose-1,6-diphosphatase activity. A therapeutic trial of orally given folic acid, 30 mg daily, did not improve her tolerance for fructose and glycerol. Over the next two years she showed improvement in tolerance to fasting, and to fructose and glycerol loading on dietary management. ( info) |