NAGLU mutations underlying Sanfilippo syndrome type B.

Sanfilippo syndrome type B (mucopolysaccharidosis III B) is a rare autosomal recessive disease caused by deficiency of alpha-N-acetylglucosaminidase, one of the enzymes required for the lysosomal degradation of heparan sulfate. The gene for this enzyme, NAGLU, recently was isolated, and several mutations were characterized. We have identified, in amplified exons from nine fibroblast cell lines derived from Sanfilippo syndrome type B patients, 10 additional mutations: Y92H, P115S, Y140C, E153K, R203X, 650insC, 901delAA, P358L, A664V, and L682R. Four of these mutations were found in homozygosity, and only two were seen in more than one cell line. Thus, Sanfilippo syndrome type B shows extensive molecular heterogeneity. Stable transfection of Chinese hamster ovary cells, by cDNA mutagenized to correspond to the NAGLU missense mutations, did not yield active enzyme, demonstrating the deleterious nature of the mutations. Nine of the 10 amino acid substitutions identified to date are clustered near the amino or the carboxyl end of alpha-N-acetylglucosaminidase, suggesting a role for these regions in the transport or function of the enzyme.

Four novel mutations underlying mild or intermediate forms of alpha-L-iduronidase deficiency (MPS IS and MPS IH/S).

The alpha-L-iduronidase deficiency diseases (Mucopolysaccharidosis I) cover a spectrum of clinical severity ranging from the very severe (Hurler syndrome, MPS IH) through an intermediate (Hurler/Scheie syndrome, MPS IH/S) to a relatively mild form (Scheie syndrome, MPS IS). Numerous mutations of the gene encoding alpha-L-iduronidase (IDUA) are known in Hurler syndrome, but only three in the other disorders. We report on novel mutations of the IDUA gene in one patient with the Scheie syndrome and in three patients with the Hurler/Scheie syndrome. The novel mutations, all single base changes, encoded the substitutions R492P (Scheie), and X654G, P496L, and L490P (Hurler/Scheie). The L490P mutation was apparently homozygous, whereas each of the others was found in compound heterozygosity with a Hurler mutation. The deleterious nature of the mutations was confirmed by absence of enzyme activity upon transfection of the corresponding mutagenized cDNAs into Cos-1 cells. These results provide additional information for genotype-phenotype correlations.

Molecular analysis of Hurler syndrome in Druze and Muslim Arab patients in Israel: multiple allelic mutations of the IDUA gene in a small geographic area.

The mutations underlying Hurler syndrome (mucopolysaccharidosis IH) in Druze and Muslim Israeli Arab patients have been characterized. Four alleles were identified, using a combination of (a) PCR amplification of reverse-transcribed RNA or genomic DNA segments, (b) cycle sequencing of PCR products, and (c) restriction-enzyme analysis. One allele has two amino acid substitutions, Gly409-->Arg in exon 9 and Ter-->Cys in exon 14. The other three alleles have mutations in exon 2 (Tyr64-->Ter), exon 7 (Gln310-->Ter), or exon 8 (Thr366-->Pro). Transfection of mutagenized cDNAs into Cos-1 cells showed that two missense mutations, Thr366-->Pro and Ter-->Cys, permitted the expression of only trace amounts of alpha-L-iduronidase activity, whereas Gly409-->Arg permitted the expression of 60% as much enzyme as did the normal cDNA. The nonsense mutations were associated with abnormalities of RNA processing: (1) both a very low level of mRNA and skipping of exon 2 for Tyr64-->Ter and (2) utilization of a cryptic splice site for Gln310-->Ter. In all instances, the probands were found homozygous, and the parents heterozygous, for the mutant alleles, as anticipated from the consanguinity in each family. The two-mutation allele was identified in a family from Gaza; the other three alleles were found in seven families, five of them Druze, residing in a very small area of northern Israel. Since such clustering suggests a classic founder effect, the presence of three mutant alleles of the IDUA gene was unexpected.

Individual and community characteristics influencing breastfeeding duration in Vietnam.

This analysis of selected community and maternal characteristics influencing duration of breastfeeding in Vietnam utilized data from the 1988 Demographic and Health Survey and 1990 Accessibility of Contraceptives Survey available for the 4434 children born to 2769 women having their last birth between 1983-88. Explanatory variables included as covariates in the hazards model were mother's education, age of the mother at the time of the child's birth, birth order, and gender of the child, urban versus rural residence, infant mortality risk in the child's province, locality (mountains and highlands compared to delta and coastal), and region of the country (north, south). Indicators of development in the child's village included availability of electricity and public transportation. Breastfeeding duration was longer among the more highly educated women and among those women living in provinces with higher infant mortality. However, there were no significant differences in the duration of breastfeeding with variations among certain development characteristics of the village. Although there were regional differences in the duration of breastfeeding for the rural population, there were no regional differences for the overall population. There were no significant variations in the duration of breastfeeding by age of the mother, birth order or gender of the child. Although there were significant variations in duration of breastfeeding by some maternal and community characteristics, between 80-90 per cent of all women breastfeed for at least the first year of the child's life.

Factors related to the utilization of prenatal care in Vietnam.

Data from the 1988 Vietnam Demographic and Health Survey and 1990 Vietnam Accessibility of Contraceptives Survey were used in this analysis of the influence of selected individual and community characteristics on the utilization of prenatal care in Vietnam. Specific analysis of the impact of availability of health services and other development characteristics of the community on utilization of prenatal care was done in a rural subsample. The woman's educational level and total number of living children were the most significant predictors of prenatal care utilization. Age independent of parity did not significantly affect the use of prenatal care. Rural women and women living in provinces with the highest infant mortality rates were significantly less likely to use prenatal services than their counterparts in the urban areas and provinces with low infant mortality rates. Non-physician health care providers were the main sources of prenatal care for women in both rural and urban areas.

PIP: Researchers analyzed data from the 1988 Vietnam Demographic and Health Survey and the 1990 Vietnam Accessibility of Contraceptives Survey to determine the influence of individual and community characteristics on use of prenatal care. Most pregnant women received prenatal care services from midwives or assistant physicians (34.8-51.2%). Less than 5% received prenatal care from a physician. Level of education and utilization of prenatal care were positively associated (p = .0001). Higher parity women were less likely to use prenatal care (47.1% vs. 68.8%), perhaps reflecting that they were more confident about pregnancy and felt less need for prenatal care. Maternal age did not affect utilization of prenatal care, regardless of parity. Urban women were more likely to use prenatal care than rural women and those living in the provinces where infant mortality was higher than 40/1000 live births. The lack of transport in rural areas was likely responsible for this difference in prenatal care utilization. Absence of prenatal care services in provinces with high infant mortality rates probably explained the difference in prenatal care use. Among rural women, the factor having the most influence on prenatal care utilization was education. These findings emphasized the need for promotion of prenatal care services among women with limited education and expansion of the accessibility and availability of prenatal services. They also indicted the importance of improving women's education which in turn improves utilization of prenatal care services.

Architecture of the canine IDUA gene and mutation underlying canine mucopolysaccharidosis I.

Mucopolysaccharidosis I (MPS I) is a lysosomal storage disease caused by deficiency of alpha-L-iduronidase. In addition to the well-known human forms (Hurler, Hurler/Scheie, and Scheie syndromes), there exists a canine model of the disease. By using previously described canine cDNA encoding alpha-L-iduronidase as a probe, the canine IDUA gene has been cloned and characterized. It contains 14 exons spread over 13 kb. An unusual GC dinucleotide was found at the donor splice site of intron 11. A transcriptional start site was identified by primer extension 177 bp upstream of the initiator AUG codon. The upstream region was found to be similar to the promoter region of many housekeeping genes: it is GC rich and has seven potential Sp1 binding sites but no TATA box or CAAT motif. The mutation in canine MPS I was localized to the area of intron 1 by RT-PCR, identified by sequence analysis of amplified genomic DNA, and confirmed by restriction analysis; it is a G-->A transition in the donor splice site of intron 1. The mutation causes retention of intron 1 in the RNA and creates a premature termination codon at the exon-intron junction.

Frequency of three Hex A mutant alleles among Jewish and non-Jewish carriers identified in a Tay-Sachs screening program.

Mutations in the HEX A gene, encoding the alpha-subunit of beta-hexosaminidase A (Hex A), are the cause of Tay-Sachs disease as well as of juvenile, chronic, and adult GM2 gangliosidoses. We have examined the distribution of three mutations--a 4-nucleotide insertion in exon 11, a G----C transversion at a 5' splice site in intron 12, and a 269Gly----Ser amino acid substitution in exon 7--among individuals enzymatically diagnosed as carriers of Hex A deficiency. Mutation analysis included polymerase chain reaction (PCR) amplification of the relevant regions of genomic DNA, followed by allele-specific oligonucleotide hybridization; another test for heterozygosity of the exon 11 insertion was based on the formation of heteroduplex PCR fragments of low electrophoretic mobility. The percentage distribution of the exon 11, intron 12, exon 7, and unidentified mutant alleles was 73:15:4:8 among 156 Jewish carriers of Hex A deficiency and 16:0:3:81 among 51 non-Jewish carriers. Regardless of the mutation, the ancestral origin of the Jewish carriers was primarily eastern and (somewhat less often) central Europe, whereas for the non-Jewish carriers it was western Europe. Because a twelfth of the Jewish carriers and four-fifths of the non-Jewish carriers of Hex A deficiency had mutant alleles other than the three common ones tested, enzyme-based tests cannot be replaced by DNA-based tests at the present time. However, DNA-based tests for two-carrier couples could identify those at risk for the chronic/adult GM2 gangliosidoses rather than for infantile Tay-Sachs disease.