Prenatal diagnosis of infantile sialic acid storage disease in a twin pregnancy

Summary A diagnosis of infantile sialic acid storage disease was made in an infant who died aged 17 months. In the mother's next pregnancy no morphological or biochemical abnormality was found in chorionic villi, amniotic fluid, cultured amniotic fluid cells or fetal blood and a normal boy was born. In the subsequent pregnancy an ultrasound scan revealed a twin pregnancy. Chorionic villus samples were obtained from both twins and microscopic and biochemical analysis indicated one twin to be affected with sialic acid storage disease. Selective fetocide was performed. The unaffected twin proceeded to term.     

Cholestatic liver disease in long-term infantile nephropathic cystinosis

Background:  Cystinosis is a metabolic disease characterized by accumulation of cystine in different organs and tissues, leading to potentially life-threatening organ dysfunction. Infantile cystinosis typically leads to end-stage renal disease, necessitating renal replacement therapy. Liver disease in cystinosis is rare and is mostly reported as nodular regenerative hyperplasia leading to portal hypertension.
Methods:  Two patients with infantile cystinosis developed cholestatic liver disease (increasing alkaline phosphatases, gamma-glutamyltransferase and mild increase in transaminases). Severe accumulation of cystine was demonstrated on liver biopsy, predominantly localized in Kupffer cells, together with morphological signs of sclerosing cholangitis on liver biopsy. One patient showed changes compatible with sclerosing cholangitis on magnetic resonance imaging. Therapy with ursodeoxycholic acid led to biochemical improvement in one and stabilization in the other patient.
Conclusion:  Long-term infantile nephropathic cystinosis can be associated with a form of sclerosing cholangitis, which can respond to therapy with ursodeoxycholic acid.     

The effect ofd-(+)-glucosamine on levels of freeN-acetylneuraminic acid and UDP-N-acetylhexosamines in infantile sialic acid storage disease (ISSD) fibroblasts

An impairment in the regulation ofN-acetylneuraminic acid (NANA) biosynthesis might potentially contribute to accumulation of free NANA in fibroblasts of patients with sialic acid storage disease (ISSD). By the use of a glucosamine loading test an increase in uridine-diphosphate-N-acetyl-hexosamines (UDP-HexNAc) but not in free NANA was found. NANA biosynthesis therefore appears to be under normal regulatory control in ISSD.     

Prenatal screening of sialic acid storage disease and confirmation in cultured fibroblasts by LC-MS/MS

Sialic acid storage disease (SASD) is an inborn error resulting from defects in the lysosomal membrane protein sialin. The SASD phenotypical spectrum ranges from a severe presentation, infantile sialic acid storage disease (ISSD) which may present as hydrops fetalis, to a relatively mild form, Salla disease. Screening for SASD is performed by determination of free sialic acid (FSA) in urine or amniotic fluid supernatant (AFS). Subsequent diagnosis of SASD is performed by quantification of FSA in cultured fibroblasts and by mutation analysis of the sialin gene, SLC17A5. We describe simple quantitative procedures to determine FSA as well as conjugated sialic acid in AFS, and FSA in cultured fibroblasts, using isotope dilution (¹³C₃-sialic acid) and multiple reaction monitoring LC-ESI-MS/MS. The whole procedure can be performed in 2–4 h. Reference values in AFS were 0–8.2 μmol/L for 15–25 weeks of gestation and 3.2-12.0 μmol/L for 26–38 weeks of gestation. In AFS samples from five fetuses affected with ISSD FSA was 23.9-58.9 μmol/L demonstrating that this method is able to discriminate ISSD pregnancies from normal ones. The method was also validated for determination of FSA in fibroblast homogenates. FSA in SASD fibroblasts (ISSD; 20–154 nmol/mg protein, intermediate SASD; 12.9-15.1 nmol/mg, Salla disease; 5.9-7.4 nmol/mg) was clearly elevated compared to normal controls (0.3-2.2 nmol/mg). In conclusion, we report simple quantitative procedures to determine FSA in AFS and cultured fibroblasts improving both prenatal diagnostic efficacy for ISSD as well as confirmatory testing in cultured fibroblasts following initial screening in urine or AFS.     

Biochemical characterization of patients and prenatal diagnosis of sialic acid storage disease for three families

Summary Modifications of the assay method of Aminoff (1961) for the determination of sialic acid levels in urine, amniotic fluid, cultured cell homogenates and tissue homogenates, which reduce the interference from proteins by precipitation and from interfering chromogens by second derivative spectroscopy are described.Biochemical profiles of patients from three families with different clinical forms of sialic acid storage disease were made using data obtained with the new method. A family with two patients with the clinically severe, early-onset form is described, in which a 9-fold elevation of sialic acid can be detected in the skin fibroblasts and a 12-fold elevation in the urine. A patient from the second family is described with very severe clinical features and with 160-fold and 16-fold elevations of sialic acid in the urine and skin fibroblasts respectively. A patient from a third family is described with mild clinical features but with a 160-fold and 6-fold elevation of sialic acid in urine and skin fibroblasts respectively. The data obtained in this study are compared with data obtained in other laboratories on other patients.The method was used to assess the levels of sialic acid present in amniotic cells and chorionic villus cells obtained prenatally from pregnancies in each of the three families. In one case, in which amniotic cells were elevated in sialic acid and were vacuolated, the pregnancy was terminated. Follow-up studies confirmed the diagnosis. Pregnancies from the other two families were assessed to be not affected.     

Peroxisomes in infantile phytanic acid storage disease: a cytochemical study of skin fibroblasts

Cultured skin fibroblasts from six patients demonstrating clinical signs and biochemical characteristics of infantile phytanic acid storage disease (IPSD) were examined by electron microscopy, using cytochemical procedures for the demonstration of peroxisomal catalase activity. In four of the six fibroblast cell lines peroxisomes strongly reactive for catalase were present in numbers similar to those found in normal fibroblasts. Liver biopsy tissue from one of these patients showed no typical hepatic peroxisomes, but did show small, marginally reactive bodies. In two other IPSD fibroblast cell lines peroxisomes with appreciable cytochemical reactivity were rare or absent. It seems, therefore, that infantile phytanic acid storage disease is heterogeneous with respect to the presence of cytochemically recognizable peroxisomes, at least in the cases studied here. Furthermore, peroxisomes may be markedly affected in one cell type — liver — and yet not affected in another — skin fibroblasts — within a single individual.     

The role of sialic acid in the dysfibrinogenemia associated with liver disease: distribution of sialic acid on the constituent chains

To further evaluate the role of sialic acid in the dysfibrinogenemia associated with liver disease, we studied the effect of removal of excess sialic acid residues from the fibrinogen of five patients with liver disease on the thrombin time and fibrin monomer aggregation. Patient fibrinogens containing 1.4-3.4 residues of sialic acid per molecule in excess of normal controls, with thrombin times 12-22 sec longer than normal and with abnormal fibrin monomer aggregation, were stripped of their excess sialic acid by incubation with Vibrio cholerae neuraminidase, followed by rapid removal of the enzyme by antineuraminidase antibody affinity chromatography. These partially desialylated patient fibrinogens, with a normal number of sialic acid residues remaining, exhibited normal thrombin times and normal fibrin monomer aggregation. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of reduced normal, patient, and partially desialylated patient (sialyl-3H)-fibrinogen exhibited 60% of the radioactivity in the B beta chain and 40% in the gamma chain. There was no radioactivity detectable in the A alpha chain. These studies provide additional evidence that the increased sialic acid content of the acquired dysfibrinogenemia of liver disease is responsible for its functional defect and that the excess sialic acid is distributed on the B beta chain and gamma chains of the fibrinogen.     

Significance of serum sialic acid in patients with Crohn's disease.

Serum sialic acid was measured to evaluate the activity of Crohn's disease. The sialic acid levels of patients with Crohn's disease in remission (CRP 0.0 mg/dl) were significantly higher than those of healthy subjects and postoperative patients with Crohn's disease. In patients in remission, serum sialic acid was significantly correlated with hemoglobin, hematocrit, platelet, and rapid turnover protein. Correlations with platelet, retinol-binding protein, and prealbumin were especially strong. From these findings, it was concluded that serum sialic acid level provides a useful index of the activity of Crohn's disease.     

Atypical phenotype in a boy with a maple syrup urine disease

Summary Maple syrup urine disease (MSUD) is a metabolic disorder due to a block in the decarboxylation step in the catabolic pathways of the branched-chain amino acids (BCAAs). We describe an atypical presentation in an infant male. The patient presented with psychomotor retardation, profound hypotonia and elevated plasma levels of BCAAs, but no elevation of alloisoleucine. Cranial magnetic resonance imaging showed prominent diffuse CSF spaces, delayed myelin maturation and symmetrical signal abnormality within the globi pallidi, midbrain, dorsal pons and medulla. The cerebellar white matter was specifically spared. A mitochondrial disorder was suggested. After correction of feeding problems with G-tube feeds, his high BCAAs persisted and, on fourth analysis, alloisoleucine was seen. Subsequent fibroblast enzyme and mutation analysis confirmed MSUD due to E₁-α subunit deficiency. After starting dietary treatment, there was no significant improvement in his hypotonia or his psychomotor development. However, the high signal within the globi pallidi had resolved. MSUD may have diverse clinical presentations, and should be considered in children who present with chronic psychomotor delay but no acute encephalopathic episodes. BCAA levels may not be very high, alloisoleucine may not always be detected in MSUD even with severe enzyme deficiency, and imaging may be misleading if seen in the chronic phase only. Communicating editor: Georg Hoffmann Competing interests: None declared     

Chemical compositions of acid mucopolysaccharides in urine and tissues of patients with multiple sulphatase deficiency

Detailed chemical analyses of the acid mucopolysaccharides of liver, brain and urine in multiple sulphatase deficiency have shown heparin sulphate to be the major component.     

Role of sialic acid in erythrocyte survival

The role of membrane sialic acid in erythrocyte survival is unclear, although there is evidence for a reduction in sialic acid and surface charge in older erythrocytes. We reduced the surface charge of human, rat, and rabbit erythrocytes by removing sialic acid with neuraminidase. Reduction in sialic acid correlated with decreases in electrophoretic mobility and loss of PAS staining of membrane glycoproteins on polyacrylamide gels. No changes in ATP levels or deformability were found. 51Cr erythrocyte survivals in rats and rabbits showed rapid clearance of desialylated erythrocytes with sequestration by the liver. These results suggest that reduction in erythrocyte sialic acid is a mechanism of erythrocyte destruction and may be important in erythrocyte senescence.     

Total and ganglioside-bound sialic acid content of lymphocytes from non-insulin-dependent diabetic patients

Summary The total and ganglioside-bound sialic acid content of unfractionated blood lymphocytes obtained from normal-weight healthy subjects (n=17) and non-insulin-dependent diabetic patients on oral hypoglycemic drugs arbitrarily divided into normal-weight (n=11), moderately overweight (n=14) and severely overweight (n=17) subgroups were examined. In normal-weight diabetics the level of lipid-bound sialic acid (gangliosides) of lymphocytes was found to be reduced (p<0.01). A more pronounced decrease (p<0.001) was observed for the lymphocyte total sialic acid of normal-weight and moderately overweight diabetics as compared to healthy subjects. In severely overweight non-insulin-dependent diabetics the decrease of total sialic acid was less pronounced compared to that found in healthy subjects. Whether this finding was due to obesity in these patients remains to be clarified.     

Role of serum total sialic acid in differentiating cholangiocarcinoma from hepatocellular carcinoma

AIM:This study was designed to evaluate the clinical application of serum total sialic acid (TSA) in the diagnosis of cholangiocarcinoma (CCA).METHODS: Serum TSA was determined by periodateresorcinol microassay in 69 patients with CCA, 59 patients with hepatocellular carcinoma (HCC), 37 patients with cirrhosis, 61 patients with chronic hepatitis and 50 healthy blood donors.RESULTS: The mean serum TSA concentration in CCA (2.41±0.70 mmol/L) was significantly higher than those of HCC, cirrhosis, chronic hepatitis and healthy blood donors (1.41±0.37 mmol/L, 1.13±0.31 mmol/L, 1.16±0.26 mmol/L, and 1.10±0.14 mmol/L, respectively; P＜0.001). Based on ROC curve analysis, a cut-off point of 1.75 mmol/L discriminated between CCA and HCC with a sensitivity,specificity and accuracy of 82.6%, 83.1%, and 82.8%,respectively.CONCLUSION: Based on our results, serum TSA would be a useful marker for the differential diagnosis of CCA from HCC.     

Content and thrombin-induced release of acid hydrolases in gel-filtered platelets from patients with storage pool disease

The levels of four acid hydrolases, beta-N-acetyl glucosaminidase, beta- glucuronidase, beta-galactosidase, and acid phosphatase, and the extent of their release (release II) by thrombin was determined in platelets from nine normal subjects, nine patients with storage pool disease, and in normal platelets which had been exposed to aspirin. The levels of all four hydrolases were normal in patients with SPD. However, release of three of these hydrolases (acid phosphatase was an exception) by low concentrations of thrombin (0.015 and 0.04 U/ml) was decreased in the patients as a group, although considerable variation in the extent of release of each enzyme was noted. In contrast, aspirin failed to inhibit release II in normal platelets (except for a slight impairment in the release of beta-N-acetyl glucosaminidase), although release I (serotonin, ATP and ADP) was inhibited. All release defects could be overcome by using higher concentrations of thrombin (0.2 U/ml). The normal levels of acid hydrolases in the platelets of patients with SPD (who are deficient in the platelet dense granules) suggest that these enzymes are not normally stored in the dense granules, but rather in alpha-granules. The findings also support the conclusions of previous studies that the release reaction is impaired in SPD. This release defect appears to be different from that seen in normal platelets after exposure to aspirin.     

Bile acid pool size and gallbladder storage capacity in gallstone disease

Gallstone patients have a reduced total bile acid pool size. To analyze mechanisms behind this, the relation between gallbladder storage capacity and bile acid pool size was studied in 20 gallstone patients, 15 women and 5 men. At cholecystectomy bile was aspirated from the gallbladders, and the volume of bile and concentration of bile acids were recorded. The total bile acid pool size was at the same time estimated by an isotope dilution technique. A significant positive correlation between gallbladder volume and bile acid pool size was found (r = 0.45). The correlation between bile acid concentration in the gallbladders and pool size was, however, not significant (r = 0.24). It is suggested that gallbladder storage capacity may be a determinant of bile acid pool and that a diminished pool size, as seen in gallstone disease, may to some extent be caused by gallbladder fibrosis and shrinkage.