Altered lysosomal glycohydrolase activities in juvenile diabetes mellitus.

Studies have been carried out on activities of lysosomal beta-N-acetylhexosaminidase (hex), beta-galactosidase (beta-gal), alpha-glucosidase (alpha-glu), and acid phosphatase (AP) in serum and urine from patients with juvenile diabetes and matched controls. There is a large increase in blood and urinary hex activity (the former presenting three distinct patterns of abnormality), a moderate increase in urinary beta-gal, and a small increase in urinary alpha-glu activity, but no elevation of blood or urinary AP in the diabetics. Urinary alpha-glu activity in the diabetics shows striking inhibition by glucose, and this may reflect a similar phenomenon in vivo. Although glycohydrolase activities are elevated in patients with no detectable microangiopathy, more striking changes may be observed in patients with severe small-vessel disease. These alterations may be associated with increased glycoprotein catabolism in the diabetic, an area in need of further studies in the human and experimental diabetic animal.

Changes of serum hexosaminidase for the presumptive diagnosis of type I Gaucher disease in Tay-Sachs carrier screening.

Although reduced acid beta-glucosidase activity appears to be the primary enzyme defect in type I Gaucher disease, patients with this disorder also have marked elevation of serum acid phosphatase and beta-hexosaminidase activities but with a normal level of lactic dehydrogenase activity. Moreover, there is a characteristic alteration in the hexosaminidase isozyme distribution with a striking increase in hexosaminidase B. Since these changes appear to be consistent and unlike those associated with other disorders or the hormonally induced alterations associated with pregnancy, routine serum testing for the Tay-Sachs carrier state may offer a useful approach for the presumptive diagnosis and screening for Gaucher disease. Unlike the changes in affected homozygotes, there are no characteristic alterations of acid phosphatase or hexosaminidase in heterozygotes for Gaucher disease.

Ring chromosome 6: report of a patient and literature review.

A patient with ring chromosome 6 had most of the manifestations previously reported in this syndrome and also had albinoid fundi and unilateral aniridia, findings not previously described. In most peripheral leukocyte metaphases analyzed, one chromosome 6 was replaced by a monocentric ring chromosome with deletion of the 6p and 6q. Fifteen other patients with a ring chromosome 6 have been reported. The most frequent findings were mental retardation, prenatal and postnatal failure, epicanthal folds, flat nasal bridge, short neck, apparently low-set and/or malformed ears, microphthalmia, and micrognathia. Studies of coagulation Factors XII and XIII and of the P blood group for possible assignment on distal 6p and 6q did not provide evidence for localization of the genes for these factors on the pter----p24 part of chromosome 6.

Incontinentia pigmenti in a newborn male infant with DNA confirmation.

We report on a woman with incontinentia pigmenti (IP), who had two successive term pregnancies. The first pregnancy ended in the birth of a male infant, who is alive and well at 2 years. A second liveborn male had early postnatal distress and died after 1 day of life, after a fulminating clinical course. Polymorphic microsatellite markers, closely linked to the IP gene on the X chromosome, showed that each son inherited a different X chromosome from his mother. Although in most instances IP appears to be prenatally lethal for the male, the phenotype is not completely known. We propose that the neonatal phenotype may be characterized by lethal disturbances in the hematopoietic and immunologic systems.

Human hexosaminidase isozymes: chromatographic separation as an aid to heterozygote identification.

The correct identification of Tay-Sachs heterozygotes requires a reliable procedure for separation and quantiation of the hexosaminidase isozymes. The most commonly employed method involves thermal inactivation of the heat labile hexosaminidase A assay of residual enzyme activity. This procedure, however, consistently yields a significantly lower absolute and relative activity of hexosaminidase A and a higher activity of the thermostable components (B and I) in comparison with the results obtained by DEAE-cellulose chromatography. DEAE-cellulose chromatographic separation of the hexosaminidase isozymes in serum following thermal inactivation reveals the presence of relative and absolute increase in the activity of the B and I components in addition to loss of the heat-labile A isozyme. Because the conversion of hexosaminidase A into thermostable forms by heating may vary according to the conditions employed, the thermal inactivation procedure may lead to ambiguity in heterozygote identification. This difficulty can be minimized by fractionation of the hexosaminidase isozymes by DEAE-cellulose chromatography followed by assay of the individual components. In addition to the Tay-Sachs carrier state, other conditions can alter the distribution of the hexosaminidase isozymes in tissues and body fluids. For example in serum of patients with juvenile diabetes mellitus there is a characteristic elevation of hexosaminidase B and less consistently, of hexosaminidase A. Since the activity of hexosaminidase A in serum of diabetics fractionated by ion exchange chromatography is at least as high as the activity in serum of healthy non-carriers, patients with diabetes can be easily differentiated from Tay-Sachs heterozygotes. Similarly, the distribution of the hexosaminidase isozymes in serum is altered during pregnancy, where there is usually a significant rise in hexosaminidase A and I (P). However, during pregnancy activities of hexosaminidase A and I in serum of obligate Tay-Sachs carriers are only 50% of the values observed in non-carriers at comparable gestational periods. Since the absolute activities of hexosaminidase A in serum of pregnant carriers obtained by ion exchange chromatography do not overlap with the activities in serum of non-carrier pregnant women at comparable gestational periods, this method has obvious advantages for identification of pregnancies where the fetus may be at risk for Tay-Sachs disease.

Studies on the activities and properties of lysosomal hydrolases in fractionated populations of human peripheral blood cells.

Studies have been carried out on the activities and properties of the isozymes of alpha-mannosidase, alpha-glucosidase and beta-glucosidase in granulocytes, monocytes, lymphocytes and platelts from peripheral blood of heatlhy adult donors. The findings reveal the differences in activities as well as a characteristic distribution of the different molecular forms of these lysosomal hydrolases in specific cell types. Therefore, the results obtained with unfractionated total leukocyte smples from different subjects may vary according to the distribution of cell types in the circulation. Granulocytes and monocytes show only the acid alpha-mannosidase activity whereas lymphocytes and platelets show both acid and neutral activities. The specific activity of acid alpha-mannosidase in granulocytes and monocytes is higher than in lymphocytes and platelets. By DEAE-cellulose chromatography, the acid alpha-mannosidase in granulocyte and monocyte extracts elutes as two peaks, but only one peak is seen in lymphocytes. All cell types show both acid and neutral alpha-glucosidase activities. The specific activities of both isozymes are higher in granulocytes and monocytes than in lymphocytes and platelets. Monocytes show a higher acid than neutral activity. All other cell types show a higher neutral activity. Beta-Glucosidase in all cell types is mainly membrane-bound and it can be released by Triton X-100 and sodium taurocholate. Taurocholate also stimulates the beta-glucosidase activity of granulocytes, monocytes and lymphocytes whereas it inhibits the activity of this enzyme in platelets. These results indicate that variations in the total number of leukocytes and in the relative proportion of the various cell types in health and disease may yield inconsistent or unreliable values for enzyme activity in the diagnosis of lysosomal storage disease and in carrier detection.

Human hexosaminidase isozymes. Assay of platelet activity for heterozygote identification during pregnancy.

Identification of carriers of the Tay-Sachs gene during pregnancy is difficult because of the increase in serum of a heat stable hexosaminidase isozyme I (or P) as well as changes in the relative and absolute activities of the various molecular forms of the enzyme with advancing pregnancy. In contrast, isolation of blood platelets followed by ion exchange chromatographic separation and assay of the hexosaminidase isozymes in platelet extracts by an automated method provides a sensitive and reliable method for heterozygote identification during pregnancy. This method appears superior to procedures involving thermal inactivation of extracts of peripheral blood leukocytes because of significant differences in the content of the hexosaminidase isozymes in granulocytes, lymphocytes and other cell types, as well as variations in the proportion of these cell types in samples of peripheral blood. It also alleviates the problem inherent in any method involving thermal inactivation of hexosaminidase A by avoiding possible interconversion of the various molecular forms of the enzyme associated with heating.

Heterozygote detection of type I Gaucher disease using blood platelets.

This report describes a reliable and reproducible method for the identification of carriers of Type I Gaucher disease using blood platelets as the source of beta-glucosidase and 4-methylumbelliferyl-beta-D-glucoside as substrate. Platelet lysates have at least two identifiable beta-glucosidase activities with the synthetic substrate. One is maximally active at pH 5.0 in the absence of sodium taurocholate and the other at pH 5.6 in the presence of taurocholate. In platelets of Gaucher homozygotes and heterozygotes, the beta-glucosidase activity at pH 5.6 with the bile salt is reduced whereas the activity at pH 5.0 is the same in non-carriers, carriers and affected patients. In addition to differences in specific activity, the ratio of beta-hexosaminidase to beta-glucosidase activities is a useful parameter in the evaluation of the carrier state. Since carriers have normal activity of hexosaminidase and a reduced activity of beta-glucosidase, their mean activity ratio is about 70% higher than in non-carriers. Therefore we propose that the specific activity of beta-glucosidase at pH 5.6 in the presence of sodium taurocholate with the ratio of beta-hexosaminidase to beta-glucosidase serve as useful and reliable indices in the evaluation of the carrier state for Gaucher disease.

Reproductive ability of an adult female with Silver-Russell syndrome.

An adult female with typical features of Silver-Russell dwarfism gave birth to a viable infant. Despite the abnormalities in sexual development that may be associated with the Silver-Russell syndrome, fertility is not necessarily impaired, at least in females. The growth and development of children with the Silver-Russell syndrome have been studied (Silver, 1964; Tanner et al., 1975). There is, however, virtually no information available about adult patients with this syndrome. It is known that both male and female Silver-Russell dwarfs develop secondary sexual characteristics (Rimoin, 1969; McDowell and Sproles, 1973) but fertility of these patients has not been described previously.

Split hand and food deformity and the syndrome of ectrodactyly, ectodermal dysplasia, and clefting (EEC). A report of five patients.

Five new casses of ectrodactyly are described. Two patients have the syndrome of ectrodactyly, extodermal dysplasia, and clefting (EEC). In one patient with the EEC syndrome, the disorder seems to represent a new mutation. One woman with isolated ectrodactyly has a daughter with the EEC syndrome. The variation in the clinical expression of this disorder among affected members of the same family makes it difficult to determine whether there may be several mutant alleles responsible for ectrodactyly and its related manifestations.

Cytogenetic studies in reproductive loss.

Cytogenetic studies were performed on 57 families with pregnancy wastage (eg, two or more spontaneous abortions or stillbirths). Chromosomal abnormalities were ascertained in 17 couples, through offspring with congenital malformations. Seven families had children with neural tube defects, and five families also had a previous child with Down syndrome. One mother had mosaic Turner syndrome; two additional mothers and one father had balanced chromosome translocations. These findings indicate that chromosome analyses should be performed on every couple with repeated miscarriages or malformed children, and subsequent pregnancies at risk should be monitored by amniocentesis.

Palmar crease variants and their clinical significance: a study of newborns at risk.

An analysis of palmar crease variants was carried out in a group of "at risk" newborns, without any evident congenital anomalies. This group consisted of 108 prematures, 74 infants who were small for gestational age, 62 newborns with history of gestational complications, and 46 newborns with a history of intrauterine methadone exposure. A system of classification was developed based on observations of 500 normal newborns as control subjects, 466 normal mothers, and 200 normal children. The palmar crease variants can be divided into four main groups, schematically presented as normal variants, simian crease and its variants, Sydney line and its variants, and another group of unusual variants which do not fit into the other groups. A study of these groups revealed that familial components, race, sex, and age are factors that can influence the expression of palmar crease patterns. There is an increased frequency of abnormal creases in each of the groups of "at risk" newborns. Moreover, there is an apparent association of interrupted transrerse creases and intrauterine methadone exposure.

Pregnancy outcome in women with sickle cell trait.

A prospective study was carried out to discern the outcome of pregnancy and distribution of birth weights of infants delivered of 85 women with sickle cell trait (AS) compared with a control group of 85 women with normal hemoglobin (AA) who were matched for race, age, parity, and sex of offspring. The distribution of birth weight of offspring of primiparous and multiparous women and the proportion of low-birth-weight infants did not differ significantly between infants born to mothers with AS and those in the control group. Similarly, there was no statistically significant difference between the birth weight of infants born to primipara or multipara. Also, the overall incidence of complications among women with AS did not differ from the incidence in the control group. The findings do not support previous reports that there may be definable pathologic correlates of childbearing in women with AS.

Human hexosaminidase isozymes. III. Distribution and activity of isozymes in peripheral blood leukocytes and platelets.

The specific activity and distribution of the isozymes of hex have been studied in platelets, granulocytes, monocytes, and lymphocytes isolated from venous blood. Since there are considerable differences in the content of the various hexosaminidase isozymes in these cell types, the relative activity of the A isozyme, expressed as a percent of total hexosaminidase in a mixed leukocyte preparation, is dependent on the proportion of the individual cell types present in a sample of peripheral blood. Because of variation in the proportion of cell types, the results may not accurately reflect the genotype of the blood donor. In contrast, chromatographic separation and assay of platelet extracts for activity of hexosaminidase isozymes provides a most convenient and satisfactory method of discriminating carriers and noncarriers of the Tay-Sachs mutant gene. Moreover, the ease of isolating platelets and the smaller volume of blood required compared with methods for obtaining purified leukocyte preparations offer additional advantages for identification or verification of the Tay-Sachs heterozygote state.