Search

We have studied 16 men, from 10 unrelated Italian families, affected by steroid suphatase (STS) deficiency, which is the basic defect of X-linked ichthyosis (XLI). The patients' clinical diagnoses were of either isolated ichthyosis or ichthyosis associated with Kallmann syndrome (KS) (hypogonadotropic hypogonadism and anosmia). DNA from patients and their relatives was analysed by Southern blotting followed by hydridization with an STS cDNA probe. None of the patients affected by either XLI or XLI/KS showed any hybridization signal, thus revealing a deletion in the STS gene. We suggest that a gene deletion may be the most common molecular defect involved in XLI and that the syndrome XLI/KS may be due to a deletion of both the STS and the KS loci.

Homocystinuria due to cystathionine synthase deficiency is an autosomal recessive error of sulphur amino acid metabolism characterized clinically by lens dislocation, mental retardation, skeletal abnormalities and thromboembolic phenomena. We have evaluated roentgenologically our series of 12 pediatric homocystinuric patients to detect skeletal abnormalities. Bone changes are widespread and occur mainly in dorsolumbar spine and in epi-metaphyseal growth areas. Osteoporosis is the most important finding. Dolichostenomelia and arachnodactily are relatively common. Calcific spicules occur frequently in the wrist physes.

An international questionnaire survey has been conducted to define better the natural history of homocystinuria due to cystathionine beta-synthase deficiency and permit evaluation of treatment. Data were compiled for 629 patients. Among patients not discovered by newborn screening, B6-responsive individuals on the average have significantly better mental capabilities (mean IQ, 79) than do B6-nonresponsive individuals (mean IQ, 57). Time-to-event curves are presented for the other major clinical abnormalities produced by this disease. Each occurred at significantly lower rates in untreated B6-responsive than in untreated B6-nonresponsive patients, as shown by the following examples: (1) dislocation of optic lenses (at age 10, chances of dislocation: 55% and 82%, respectively); (2) initial clinically detected thromboembolic events (at age 15, chances of having had such an event: 12% and 27%, respectively); (3) radiologic detection of spinal osteoporosis (at age 15, chances of such osteoporosis having been detected: 36% and 64%, respectively); and (4) mortality (at age 30, chances of not surviving: 4% and 23%, respectively). Methionine restriction initiated neonatally prevented mental retardation, retarded the rate of lens dislocation, and may have reduced the incidence of seizures. Pyridoxine treatment of late-detected B6-responsive patients retarded the rate of occurrence of initial thromboembolic events. Following 586 surgical procedures, 25 postoperative thromboembolic complications occurred, six of which were fatal. Reproductive histories were reported predominantly for B6-responsive patients. Living offspring of either men or women patients had few abnormalities. The evidence is inconclusive whether untreated maternal cystathionine beta-synthase deficiency leads to excessive fetal loss. Only 13% of patients detected in screening programs of newborns and classified as to B6-responsiveness were B6-responsive, compared to 47% among late-detected patients. Current screening programs that identify neonatal hypermethioninemia may be preferentially failing to detect B6-responsive patients.

We report on 2 patients with the Neuhäuser megalocornea-mental retardation syndrome, a recessively inherited clinical entity of relatively recent description (McKusick 24931). A review of the few previous reported patients and our 2 patients shows that megalocornea and mental retardation are the 2 minimal diagnostic criteria. Short stature, seizures, neurological symptoms, microcephaly or macrocephaly, and minor anomalies are all additional nonobligatory manifestations. The small number of published cases may be due to the fact that the association of these two signs has often escaped attention until now.

We measured protein-bound plasma homocyst(e)ine in 15 normal adult subjects and nine heterozygotes for homocystinuria due to cystathionine beta-synthase deficiency. The mean (+/- SD) concentrations obtained in the two groups of subjects were 4.35 +/- 1.50 and 9.16 +/- 3.40 mumoll-1, respectively. The mean values were significantly different, although the levels of three heterozygotes overlapped those of the control range. This method allows preliminary screening of the heterozygotes for homocystinuria and can be carried out by laboratories that have only facilities for amino acid analysis.

Nineteen homocystinuric patients--13 children and 6 adults--were identified in the course of a selective screening for homocystinuria due to cystathionine synthase deficiency. Treatment with high doses (300-1200 mg/day) of pyridoxine was carried out in 17 patients, of whom 15 were completely responsive. In 10 patients EEG abnormalities were observed consisting mainly of a mild diffuse non specific slowing of background activity. In two sisters, with no history of seizures, focal paroxymal activity was also recorded. EEG recordings before and after B6 treatment were available in 16 patients, one of whom was a non responder, during treatment seven normal and six abnormal EEGs showed no change whereas three previously abnormal EEGs were classified as normal.

We have investigated thiamine metabolism and transport in the erythrocytes of two patients from unrelated families with thiamine responsive megaloblastic anaemia associated with diabetes mellitus and sensorineural deafness. Both patients had low concentrations of thiamine compounds in plasma and red blood cells. When erythrocytes were incubated with thiazole-[2-14C]-thiamine or [35S]-thiamine in vitro, the concentration of label within the cells was markedly reduced compared with controls. In addition, thiamine pyrophosphokinase activity was deficient in haemolysates prepared from the patients. Some relatives of the patients showed abnormal parameters of thiamine status and transport. In both patients treatment with a lipophilic compound corrected the haematological abnormalities and diabetes and in one patient has so far prevented the progression of deafness. We propose that the disorder is caused by an inherited defect of thiamine transport, possibly related to deficient pyrophosphokinase activity, leading to intracellular depletion of active thiamine metabolite derivatives.

About 70% of the total mucosal enzymatic activity hydrolyzing beta-L-glutamyl-beta-naphthylamide in the rabbit small intestine is present in the brush border; the specific activity in this subcellular fraction is 7 times higher than that of the homogenate. Similar results are obtained for L-leucyl beta-naphthylamide hydrolase. The enzyme activity is efficiently solubilized by papain digestion and is clearly separated from L-leucyl-beta-naphthylamide hydrolase by chromatography on concanavalin A-Sepharose. It probably represents a digestive peptidase, different from the other known peptide hydrolases of the digestive surface of the small intestine.

This paper deals with a family affected by cystinuria associated with eye signs of juvenilis macular degeneration.

Peptidase and arylamidase activities were assessed in purified brush borders from jejunum of rats with surgically created blind loops. The blind loop segment and the jejunum proximal and distal to the blind loop were studied. Comparable jejunal segments from control rats were also studied. The blind loop syndrome was documented by presence of macrocytic anemia. Enzyme activities were determined on purified brush borders. In rats with the blind loop syndromes enzymatic activities hydrolizing sucrose, L-Leucyl-beta-naphthylamide, L-lysyl-beta-naphthylamide, alpha-L-glutamyl-beta-naphthylamide, L-phenylalanyl-alanine and L-leucyl-glycine were significantly reduced as compared to controls (P less than 0.001). After a short course of antibiotic therapy enzymatic activities returned to normal. Our findings suggest a reversible intestinal mucosa damage in the rat with blind loop syndrome.

Complementation studies of steroid sulphatase were carried out in the heterokaryon population of fibroblasts derived from patients with X-linked ichthyosis and multiple sulphatase deficiency. The activity of steroid sulphatase of the fused cell population was constantly higher (approximately 2-5 fold) than that of the unfused cocultivated cells. The occurrence of complementation further supports the hypothesis that at least two different loci control the expression of steroid sulphatase in the human genome.

We have developed classification coefficients and an equation to detect heterozygotes for phenylketonuria. The combination of several variables (Phe, Phe/Tyr, Phe2/Tyr) gave a safe diagnosis in more than 96% of cases. We then computerized a random selection of our population, which was divided into two groups: the first was "selected" to compute discriminant functions, while the second, excluded from computation, was used to check the fitness of our method. Despite the reduction of sample size, 95.2% of unknown subjects were correctly classified. Finally, we used our equation to detect heterozygotes for phenylketonuria in a population of 26 children, affected by non-specific mental retardation, and their mothers. We found a high proportion of carriers for phenylketonuria, defined as subjects having a percent probability of correct classification higher than 90. By this method, heterozygosity was detected in two child-mother couples, four individual children and five mothers.

A 2-year-old boy with features suggestive of cri-du-chat syndrome had a complex karyotype: 45,XY,--22,5p--,t(5p:22q). Clinical symptoms were catlike cry in early infancy, severe mental and motor retardation, failure to thrive, hypertelorism, antimongoloid slant of the eyes, ptosis of the eyelids, epicanthus, micrognathia, dermatoglyphics abnormalities, and partial syndactyly between 2nd and 3rd toes.

Immunologically cross-reacting material to antibodies against steroid sulphatase has not been found in fibroblasts from patients with steroid sulphatase deficiency.

We studied the residual alpha-N-acetylglucosaminidase activity in two siblings with severe and mild Sanfilippo B syndrome. No striking differences were demonstrated between the mutant enzymes from the severe and the mild case. However we found an altered enzyme activity characterized by displacement of the pH optimum towards basic values compared to the pH optimum of the normal enzyme, higher stability to heat and to Hg2+ ion treatment. It is suggested that the Sanfilippo B disease in this sibship is due to a mutation of a structural gene coding for alpha-N-acetylglucosaminidase.

We report a large Italian pedigree in which five out of six males are affected by a syndrome, following an X-linked inheritance pattern, characterized by ichthyosis, hypogonadotropic hypogonadism, and anosmia. The concurrence of features of X-linked ichthyosis (XLI) with those of Kallmann syndrome, another disease often inherited as an X-linked trait, prompted us to perform biochemical, cytogenetic, and molecular studies in relation to the short arm of the X chromosome (Xp). Steroid sulphatase (STS) activity was found to be completely deficient in all affected members of the family. Prometaphase chromosome analyses of two obligate heterozygous women and one affected male showed normal karyotypes. Xg blood group antigen analysis and molecular studies employing cloned DNA sequences from the distal segment of the Xp (probes RC8, 782, dic56, and M1A), did not provide evidence for deletions or rearrangements of the X chromosome. The linkage analysis showed no crossovers between the disease, Xg, and DXS143, the locus defined by probe dic56, thus suggesting the possibility of a linkage between these two markers of the distal segment of Xp and the X-linked ichthyosis, hypogonadism, and anosmia syndrome.

Cultured skin fibroblasts from a 2-year-old boy with an atypical form of beta-galactosidase deficiency have been studied. With the artificial substrate 4-methylumbelliferyl-beta-D-galactopyranoside, 5--15% residual activity was found in fibroblasts from this patient. Most of this activity was in the monomeric A form of the enzyme, very little in the multimeric B form. Km value, pH profile, and heat lability of the mutant enzyme were similar to those of beta-galactosidase from control fibroblasts. Immunological studies showed that the mutant enzyme cross-reacted with an antiserum raised against human liver beta-galactosidase, but the catalytic activity per unit antigenic activity was lower than normal. It was demonstrated by somatic cell hybridization that the gene mutation in this patient is different from that in patients with type 1 or type 2 GM1-gangliosidosis. No genetic complementation was found after fusion of fibroblasts from this patient with those from two other clinical variants of GM1-gangliosidosis formerly designated type 3 and adult type 4.

Clinical heterogeneity for Sanfilippo B syndrome (MPS III B) in the same family has never been reported previously. We describe two clinically severe cases and one clinically mild case of MPS III B in a Neapolitan sibship. We could not detect N-acetyl-alpha-D-glucosaminidase activity in the sera of either the severe or mild cases. Mucopolysacchariduria mainly due to heparan sulfate excretion was consistently high in the severely affected patients and extremely variable in the mildly affected one.

We have examined extracts of fibroblasts from patients with mannosidosis, mucolipidosis (ML) II, ML III, and normal controls for alpha-D-mannosidase activity against 4-methylumbelliferyl-alpha-D-mannopyranoside to test for the presence of the "intermediate" pH 5.5 enzyme activity that has been called the "Golgi mannosidase." Fibroblast extracts were prepared by sonication and sedimented to separate membrane-associated activities from cytosolic and lysosomal alpha-D-mannosidases. Membranes were extracted by salt washes (0.4 M NaCl) to desorb the lysosomal enzymes that sedimented with membranes. The alpha-D-mannosidase activity remaining with membranes showed many properties described for the Golgi mannosidase including: 1) an "intermediate" pH optimum (pH optimum (pH 5.5-6.0), 2) activity with the synthetic 4-methylumbelliferyl substrate, 3) lack of inhibitability by 200 mM methyl- alpha-D-mannopyranoside, and 4) partial resistance to solubilization by salt washing, and to a single extraction with the non-ionic detergent Triton X-100. This intermediate activity was the major alpha-D-mannosidase activity remaining in membranes from normal fibroblasts following sedimentation and salt washing, and was the major component of the alpha-D-mannosidase activity in extracts of fibroblasts from patients with mannosidosis, ML II, and ML III, in all of which, the lysosomal "acid" alpha-D-mannosidase was greatly reduced. The specific activity of intermediate alpha-D-mannosidase in membranes from fibroblasts from patients with mannosidosis, ML II, and ML III was not reduced compared to that of fibroblasts from controls. These studies provided no evidence to support the prior suggestion of a deficiency of "Golgi mannosidase" in ML II or ML III.

A 28-month-old child was found to have several clinical features of lysosomal storage diseases, including: coarse facies, hepatosplenomegaly, lumbar kyphosis due to hypoplastic beaked L1 and L2 vertebral bodies, vacuolated lymphocytes in blood smears and rare foamy hystiocytes in bone marrow. However, no signs of neurological or ocular abnormalities were detected. A beta-galactosidase deficiency was demonstrated in leukocytes and cultured skin fibroblasts, with a residual activity toward 4-methylumbelliferyl-beta-galactopyranoside ranging between 5 and 15% of the normal mean. Normal activities were found for several other lysosomal acid hydrolases. beta-Galactosidase activities in leukocytes and cultured skin fibroblasts from both parents were within the normal ranges. The patient seems to represent an atypical expression of acid beta-galactosidase deficiency, since his clinical picture does not exaclty correspond to that of either the two classical types of GM1-gangliosidosis or other atypical patients reported in the literature havining beta-galactosidase deficiency.