Molecular genetics of mucopolysaccharidosis type I: mutation analysis among the patients of the former Soviet Union.

Mucopolysaccharidosis type I (MPS-I) is an autosomal recessive lysosomal storage disorder resulting from a deficiency of the lysosomal protein alpha-l-iduronidase (IDUA). Patients present within a broad spectrum of phenotypes from severe (Hurler syndrome) to clinically less severe (Scheie syndrome). Since 1982 a special program for the diagnosis and prevention of lysosomal storage diseases has operated in the former Soviet Union (FSU). We report the genotypes of 25 MPS-I patients with different clinical severities from the FSU. All the patients were screened for two common mutations (W402X and Q70X) and four other mutations (P533R, R89Q, A327P, 474 2a-->g). W402X and Q70X alleles accounted for 4 and 44%, respectively. Using SSCP analysis and subsequent direct sequencing we also detected four novel mutations (P533L, Q63X, Y343X, and A75P) in the IDUA gene, together with two mutations (974ins12bp, 134del12bp) described elsewhere. All were found in the heterozygous form in MPS-I patients with different clinical severities. A total of 32 mutant alleles leading to MPS-I was identified with nine patients fully genotyped. Four patients were homozygous for Q70X while five others were genetic compounds. Besides the eight identified mutations, six known polymorphisms were found. The spectrum of mutant alleles discovered is highly specific and proves the peculiarity of genetic loads in the FSU. Our data suggest a closer relationship between the FSU and Scandinavian populations than with Western and Central European populations.

Postnatal and prenatal diagnosis of lysosomal storage diseases in the former Soviet Union.

Diagnosis and prevention of lysosomal storage diseases (LSD) in the former Soviet Union (FSU) is based on the interaction of various local counselling units with the Department of Inherited Metabolic Diseases (DIMD) at the Research Center of Medical Genetics (RAMS). Work began in 1982 using standard, as well as newly developed biochemical techniques. 25 different LSD were diagnosed in 445 patients from 404 families. 106 pregnancies in families at risk were monitored prenatally, and 25 affected fetuses were diagnosed and aborted. The clinical spectrum of diagnosed lysosomal storage diseases (LSD) was surprisingly heterogeneous. Besides classical forms of LSD numerous atypical forms were discovered. They included juvenile and adult forms of some sphingolipidoses manifesting as progressive dystonia, spinocerebellar degeneration and hebephrenic schizophrenia, as well as an atypical form of mucolipidosis III in which the clinical phenotype bore an obvious resemblance to that of mucopolysaccharidosis (MPS) VI. The incidence of MPS was much higher than that of other LSD. It was evaluated as 1:15000 for two regions of the FSU. This investigation revealed some peculiarities of the ethnic distribution of MPS in populations of the FSU and supported the high prevalence of the gene for Tay-Sachs disease gene in Ashkenazi Jews.

[Expression of lysosomal enzymes in pregnancy]. / Issledovanie ékspressii lizosomnykh fermentov pri beremennosti.

Activities of 6 lysosomal enzymes in leukocytes and 3 enzymes in blood serum were studied in pregnant women. Only activity of beta-D-glucosidase was not altered within all the pregnancy of I-III trimesters, while activity of all the other enzymes studied was distinctly increased to the third trimester. Use of the data obtained in prenatal diagnosis of lysosomal storage diseases is discussed.

High-resolution loading tests in the study of genetic heterogeneity in gangliosidosis fibroblasts.

GM1- and GM2-gangliosides were isolated from brain and radiolabelled. The labelled moieties were localized by hydrolysis with lysosomal enzymes, followed by thin-layer chromatography of the products. High-resolution loading tests with labelled gangliosides were developed and found to differentiate infantile and juvenile forms of GM1- and GM2-gangliosidoses as well as the identification of B, O and AB types of GM2-gangliosidosis.

Diagnosis and prevention of lysosomal storage diseases in Russia.

A special programme for the diagnosis and prevention of lysosomal storage diseases (LSD) was developed in the former USSR. All the patients from 814 families at risk were investigated using biochemical techniques. In total, 363 patients with mucopolysaccharidoses (MPS), mucolipidoses, glycoproteinoses, sphingolipidoses and other LSD were diagnosed; 55 families at risk sought prenatal diagnosis and 67 fetuses were investigated for MPS (types I, II, IIIA and IIIB, VI), Tay-Sachs disease, Sandhoff disease, GM1-gangliosidosis, metachromatic leukodystrophy, mannosidosis, Gaucher disease and multiple sulphatidosis; 17 affected fetuses were diagnosed and aborted. There was an ethnic distribution of different lysosomal storage diseases in the former USSR.

[A program of prevention of hereditary lysosomal diseases in the USSR]. / Programma profilaktiki nasledstvennykh lizosomnykh boleznei v SSSR.

The organization of genetic counselling for the families of patients with lysosomal storage diseases (LSD) was based on the interaction of the genetic counselling units of this country with a laboratory of inherited metabolic diseases of the National Research Center of Medical Genetics, USSR AMS. All the patients from 705 families at risk were examined using biochemical techniques and methods of somatic cell genetics. In total the loci differentiation was performed for 309 patients with mucopolysaccharidoses, glycoproteinoses, mucolipidoses, sphingolipidoses and other LSD. 53 families at risk (of 277) were prenatally diagnosed. 66 fetuses were diagnosed for mucopolysaccharidoses, type I, II, III, A and B, VI, Tay-Sachs disease, Sandhoff's disease, GM1-gangliosidosis, metachromatic leukodystrophy, mannosidosis, and multiple sulfatidosis. In total 18 affected fetuses were diagnosed and aborted. All the prenatal diagnoses were verified. The prevalence of mucopolysaccharidoses in two Central Asian republics was evaluated as 1:15,000. An Uneven ethnic distribution of different mucopolysaccharides in the USSR has also been shown.

[Biochemical diagnosis of mucosulfatidosis]. / Biokhimicheskaia diagnostika mukosul'fatidoza.

Biochemical anomalies in proband involved alterations in the spectrum of glycosaminoglycans (GAG) excreted with urine as well as a decrease in activity of lysosomal sulfatases (arylsulfatases A and B, heparan-N-sulfatase) in homogenates of leukocytes and cultivated fibroblasts. In healthy parents of the proband activity of the sulfatases was lower than in control donors but higher as compared with the proband. Antenatal diagnostics of mucosulfatidosis was carried out in fetus during the repeated pregnancy. The following biochemical anomalies were noted: alteration in the GAG spectrum in amniotic fluid, decrease in activity of lysosomal sulfatases in cultivated cells of the amniotic fluid. The pregnancy lead to a premature birth at 31st week of a girl. No alterations were observed in the spectrum of GAG's excreted with urine and in intracellular accumulation of 35S-GAG in the newborn child. Measurement of sulfatases activity in leukocytes enabled to identify conclusively that the child was a heterozygotic bearer mucosulfatidosis.

[Study of the genetic heterogeneity of gangliosidoses in humans]. / Issledovanie geneticheskoi geterogennosti gangliozidozov u cheloveka.

A study of genetic heterogeneity of GM1 and GM2 gangliosidoses was performed using a wide set of cultured fibroblast lines of patients with leukodystrophies. In addition to commonly used methods for enzyme diagnosis and for isozyme fractionating, following assays were developed for locus and allele differentiation: loading tests with 3H-GM1 and 3H-GM2, analytical chromatofocusing and activity determination of activator protein for GM2.

[The use of loading tests with labeled GM1-ganglioside for differential diagnosis of GM1-gangliosidosis]. / Ispol'zovanie nagruzochnykh testov s pomoshch'iu mechenogo GM1-gangliozida dlia differentsial'noi diagnostiki GM1-gangliozidoza.

Kinetics of GM1-ganglioside accumulation was studied in fibroblast cultures from patients with various forms of GM1-gangliosidosis using the labelled native substrate GM1-ganglioside isolated from human brain. A shape of accumulation curves in the plot was shown to depend on GM1-ganglioside concentration in a medium in juvenile form of the disease. Use of a number of the fibroblast strains and optimal concentration of GM1-ganglioside 20 micrograms/ml enabled to carry out allele differentiation of the juvenile form of GM1-gangliosidosis from infantile and normal forms, thus suggesting that the loading tests could be applied to pre- and postnatal diagnosis of GM1-gangliosidosis.

[Prenatal diagnosis of hereditary lysosomal diseases]. / Prenatal'naia diagnostika nasledstvennykh lizosomnykh boleznei.

Prenatal diagnosis was carried out in 10 families suffering from lysosomal diseases: Tay-Sachs disease--5 families, Sandhoff disease--1 family, GM1-gangliosidosis--1 family and Hunter disease--3 families. Diagnosis of Tay-Sachs disease was excluded in fetuses of two families, Sandhoff disease--in one family, GM1-gangliosidosis--in one family, Hunter disease--in two families. Tay-Sachs disease was found in two fetuses and in one neonate. In two fetuses was found Hunter disease (twin pregnancy). The results of prenatal diagnosis were corroborated by postnatal studies of the neonates funicular blood and of autopsies of the aborted fetuses tissues. Application of several independent procedures for prenatal diagnosis of hereditary lysosomal diseases enabled to exclude erroneous diagnosis.