Detection of carriers and prenatal diagnosis for fucosidosis in Calabria

Plasma α-L-fucosidase-1 in patients with Sjögren's syndrome and other rheumatic disorders

BACKGROUND

Human α-fucosidase (EC 3.2.1.51) is a hydrolase the importance of which has been increasing in the latest years. However, data about its plasma level in children with autoimmune disorders, particularly Sjögren's syndrome (SS), are lacking. In this study, the plasma activity of L-α-fucosidase-1 (α-L-FUCA-1) was assayed in hospitalized children and adults and its association with SS and other rheumatic disorders further evaluated.

METHODS

In total 73 Hungarian hospitalized patients, 32 children (2.5-10 years) and 41 adults (32-68 years), were enrolled in the study and underwent plasma assay of α-L-FUCA1 activity. Linear regression, Durbin-Watson (DW), and Pearson tests were evaluated to investigate the relationship between α-L-FUCA-1 plasma levels and autoimmune manifestations.

RESULTS

α-L-FUCA-1 correlated with SS both in children (2-sided t test, P = 0.0023) and in adults (2-sided t test, P = 0.00035). Linear regressions showed that in other rheumatic disorders, α-L-FUCA1 did not show any differential distribution related to the particular pathology (r = 0.2042, P = 0.1531, DW test = 2.2139 positive), while this trend was radically opposite for patients with SS (r = 0.1462, P = 0.0032, DW test = 1.3664, negative).

CONCLUSIONS

Alterations in plasma level of α-L-FUCA-1 were significantly associated with SS. This preliminary result should encourage further research on α-L-FUCA-1 as a possible differential serological marker of SS.

Phenotypic spectrum of fucosidosis in Tunisia

Fucosidosis (OMIM 230000) is a rare autosomal recessive lysosomal disorder due to deficient α-L-fucosidase activity(EC 3.2.1.51), leading to the accumulation of fucose-containing glycolipids and glycoproteins in various tissues. This study contained the largest ever Tunisian survey of fucosidosis patients, diagnosed during the period 1987-2007. The clinical pictures and outcomes of these patients are compared with literature data. Ten patients (8 boys and 2 girls) from six unrelated families were diagnosed at a mean age of 29 ± 10.3 months. Six of the patients were diagnosed as having the more severe phenotype. The other four cases presented the low progressive phenotype. This distinction was determined by the presence or absence of angiokeratoma and age of death. For all of the patients in our survey, early motor development was more severely delayed than described in the literature. Six patients presented psychomotor decline during the second year of life. Clinical features consist of variable mental retardation (all patients), progressive spastic quadriplegia (6/10 cases), coarse facies (9/10 cases), growth retardation (7/9 cases), visceromegaly (3 cases), angiokeratoma corporis diffusum (4 cases), recurrent bronchopneumonias (all cases), seizures (4 cases) and variable degrees of dysostosis multiplex (all cases). Portal cavernoma, never described in the literature, was observed in one patient. The outcomes were severe in this survey, probably owing to restricted health care; death occurred in 6 of the 10 patients before age 10 years, following recurrent pulmonary infections and neurological deterioration. No intrafamilial variability was noted in the multiplex families. The clinical presentation and outcomes of some of these patients were consistent with the continuous clinical spectrum of severity in fucosidosis attested by most clinical studies.

Infantile sialic acid storage disease: biochemical studies

Infantile free sialic acid storage disease (ISSD), is an inherited metabolic disorder characterized by hyperexcretion of free sialic acid in the urine and by its storage in the lysosomes of different tissues. In order to obtain more reliable data on the amount of total and free sialic acid, we analyzed the urine, brain, cerebellum, liver, spleen, and kidneys from a 3-month-old baby who died with a diagnosis of ISSD. The lysosomal nature of the disease was confirmed by an electron microscopic study of cells in culture. No significant abnormalities were found involving cholesterol, total phospholipids, glycolipids, and gangliosides in the tissues examined. However, differences in the tissue distribution of individual glycolipids and gangliosides were observed. The amount of free and total sialic acid was markedly increased, due to the storage of free sialic acid accompanied by its hyperexcretion in the urine. These results demonstrate and confirm that only acid monosaccharide transport from the lysosome compartment is involved in the pathogenesis of ISSD.

Fucosidosis revisited: a review of 77 patients

Fucosidosis is a rare, autosomal recessive, lysosomal storage disorder caused by a severe deficiency of alpha-L-fucosidase in all tissues. We have conducted a review of fucosidosis, compiling data from published reports and an international questionnaire survey. Seventy-seven patients affected with fucosidosis of which 19 had not been reported before have been identified. A major aim of the present study was to define the natural history of fucosidosis. The clinical picture of fucosidosis consists of progressive mental (95%) and motor (87%) deterioration, coarse facies (79%), growth retardation (78%), recurrent infections (78%), dysostosis multiplex (58%), angiokeratoma corporis diffusum (52%), visceromegaly (44%), and seizures (38%). Whereas the original fucosidosis patients described by Durand et al. (J. Pediatr 75:665-674, 1969) were decerebrate and died before age 5 years, most fucosidosis patients have a slower course of degeneration. Mortality before age 5 years was observed in only 7 patients (9%), whereas 36 patients (64%) reached the second decade. We did not find evidence for the existence of clinical heterogeneity with a rapidly progressive type I and a slowly progressive type II fucosidosis as suggested in the literature. Instead, there seems to exist a wide continuous clinical spectrum. At the biochemical level no heterogeneity in residual fucosidase enzyme activity or cross-reacting immunoreactive fucosidase protein was observed. At the DNA level at least 4 different mutations must be responsible for fucosidosis. These genotypic differences however do not explain the observed phenotypic differences.

Heterogeneity of mRNA expression in Italian fucosidosis patients

Genomic DNA and mRNA from six unrelated Italian patients affected with fucosidosis were analyzed using two probes (AF3 and AF11B) of partial length cDNA coding for the lysosomal enzyme alpha-L-fucosidase. DNA from patient 2, digested with EcoRI, showed a variant pattern of hybridization caused by the loss of an EcoRI site. The same patient showed a markedly decreased amount of mRNA on Northern blot hybridization. Among the remaining patients, who showed no variation at the DNA level, two apparently lacked mRNA for alpha-L-fucosidase whereas the other three showed a transcript similar in size and amount to that observed in controls. These data confirm the genetic heterogeneity of the molecular defects causing fucosidosis in Italy.

Fucosidosis: ultrastructural study of the eye in an adult

The ocular histopathological and ultrastructural features of fucosidosis in a man who survived to the age of 25 years are reported. Virtually all of the cells of the eye contained cytoplasmic, membrane-bound, and confluent areas of fibrillogranular and multilaminated material. The most striking accumulations were present within the endothelial cells lining blood vessels and corneal endothelium, and the least amount was present in the uveal melanocytes.

Intrafamilial variability in fucosidosis

Two families with five patients affected with fucosidosis are described. Within each family, both type I and type II fucosidosis are present. This suggests that environmental factors or "modifying genes" different from the fucosidase structural gene contribute to the phenotype of a fucosidosis patient.

Progressive cone dystrophy associated with low alpha-L-fucosidase activity in serum and leukocytes

The enzyme activities of acid phosphatase, beta-glucuronidase, N-acetyl-beta-D-glucosaminidase, and alpha-D-mannosidase were not significantly different in patients with myopia, retinal detachment, hereditary macular dystrophy, and unusual progressive cone dystrophy. alpha-L-Fucosidase activity in sera was lower in three patients with myopia and in two patients with unusual progressive cone dystrophy than in most of the others. Leukocytic alpha-L-fucosidase activity was lower in those with unusual progressive cone dystrophy. The two unrelated patients with unusual progressive cone dystrophy had slowly deteriorating visual acuity, color vision, and photopic electroretinographic responses, but ophthalmoscopically normal fundi and noncontributory family histories.

Prenatal diagnosis of mucopolysaccharidosis I: A special difficulty arising from an unusually low enzyme activity in mother's cells

We investigated a case (I.I.) of the severe form of mucopolysaccharidosis I (Hurler syndrome). Prenatal diagnosis was requested by the parents and the next pregnancy was monitored. We report here a special difficulty arising in this diagnosis due to the low enzyme activity in the mother's cells (10-15 per cent of controls) as well as in amniotic cells and would like to stress the need for studying the index case as well as the parents' enzyme activities in order to be prepared for possible difficulties at prenatal analysis.