Chinese Cases of Metachromatic Leukodystrophy with the Novel Missense Mutations in ARSA Gene.

Metachromatic leukodystrophy(MLD) is an autosomal recessive hereditary neurodegenerative lysosomal storage disorder caused by the mutations in arylsulfatase A gene (ARSA), which results in the deficiency of ARSA enzyme. The common clinical characteristics of MLD are abnormal gait, and then gradually appears ataxia, spastic quadriplegia, optic atrophy, cortical blindness, and dementia. We describe two patients in China who were diagnosed with MLD and find that the four ARSA gene mutations (c.1115G>A, c.302G>T, c.893 G> T, and c.302G>T) are associated with MLD, in which c.893 G>T and c.302G>T are novel mutations by gene sequence and clinical manifestations, to further understand the relationship between MLD and ARSA gene.

Metachromatic leukodystrophy genotypes in The Netherlands reveal novel pathogenic ARSA variants in non-Caucasian patients.

Metachromatic leukodystrophy (MLD) is an autosomal recessively inherited sulfatide storage disease caused by deficient activity of the lysosomal enzyme arylsulfatase A (ASA). Genetic analysis of the ARSA gene is important in MLD diagnosis and screening of family members. In addition, more information on genotype prevalence will help interpreting MLD population differences between countries. In this study, we identified 31 different ARSA variants in the patient cohort (n = 67) of the Dutch expertise center for MLD. The most frequently found variant, c.1283C > T, p.(Pro428Leu), was present in 43 (64%) patients and resulted in a high prevalence of the juvenile MLD type (58%) in The Netherlands. Furthermore, we observed in five out of six patients with a non-Caucasian ethnic background previously unreported pathogenic ARSA variants. In total, we report ten novel variants including four missense, two nonsense, and two frameshift variants and one in-frame indel, which were all predicted to be disease causing in silico. In addition, one silent variant was found, c.1200C > T, that most likely resulted in erroneous exonic splicing, including partial skipping of exon 7. The c.1200C > T variant was inherited in cis with the pseudodeficiency allele c.1055A > G, p.(Asn352Ser) + ∗96A > G. With this study we provide a genetic base of the unique MLD phenotype distribution in The Netherlands. In addition, our study demonstrated the importance of genetic analysis in MLD diagnosis and the increased likelihood of unreported, pathogenic ARSA variants in patients with non-Caucasian ethnic backgrounds.

Racial/Ethnic and Insurance Status Disparities in Distance Traveled to Access Children's Hospital Care for Severe Illness: the Case of Children with Leukodystrophies.

Families of children with special health care needs may travel substantial distances to access specialized health care. However, it is not known how race/ethnicity, insurance status, and access to disease-specific specialty care affect travel distances. This analysis examines patients aged 18 years or younger who were discharged from a Pediatric Health Information System (PHIS) children's hospital (n = 52) with a diagnosis of an inherited leukodystrophy between October 1, 2015, and September 30, 2018 (n = 950 patients). Leukodystrophies are rare but very serious neurological illnesses, with elevated mortality and morbidity rates. Bivariate and hierarchical generalized linear models reveal that white children, privately insured children, and children visiting leukodystrophy specialist centers travel farther for children's hospital care. These findings indicate that socially privileged families travel greater distances to obtain specialized health care, which could affect clinical outcomes.

Molecular and structural analysis of metachromatic leukodystrophy patients in Indian population.

Metachromatic leukodystrophy (MLD) is an autosomal recessive disorder caused by mutations in arylsulfatase A (ARSA) gene. No work on molecular genetics of MLD has been reported from India and the mutational spectrum in Indian patients is not known. The present study was undertaken to identify mutations in arylsulfatase A gene in Indian MLD patients, to evaluate genotype-phenotype correlation, and to see the effect of the novel mutants on the protein. Twenty MLD patients (16 families) were screened by ARMS PCR for the most common mutation (c.459+1G>A). Pseudodeficiency alleles were tested by RFLP method whereas rare and novel mutations were scanned by Conformation Sensitive Gel Electrophoresis (CSGE), followed by sequencing. The genotype-phenotype correlation was also attempted. Protein homology modeling analysis was carried out for two novel missense mutations identified, to assess the effect of these mutations on the protein conformation. Nine pathogenic alleles were found in 13 patients (65%). Four previously reported mutations and five novel variants were identified. Five patients (35%) were found to have pseudodeficiency alleles, c.1049A>G (p.Asn350Ser) and c.1524+95A>G. Genotype-phenotype correlation was found to be difficult to establish. Protein modeling studies showed that the mutations cause loss of interactions leading to conformational change in ASA protein. The study identified the mutational spectrum of Indian MLD patients, which will be helpful in genetic counseling, carrier detection and establishing prenatal diagnosis. Homology modeling helped to study conformational change in protein and has implications in generating novel therapeutic molecules.

Identification of a new Arylsulfatase A (ARSA) gene mutation in Tunisian patients with metachromatic leukodystrophy (MLD).

Metachromatic leukodystrophy (MLD) is an autosomal recessive, lysosomal storage disease caused by a deficiency of the enzyme arylsulfatase A (ARSA). The aim of the present study was to identify the molecular basis of MLD in Tunisian population. Two Tunisian patients with late infantile MLD were studied. Both patients were homozygous for a new missense mutation that causes a substitution of Trp in Gly p.W124G. This is the first mutation of ARSA gene described in Tunisian population.

ARSA gene mutations in five Chinese metachromatic leukodystrophy patients.

The objective was to identify arylsulfatase A mutations, if any, in five Chinese patients with metachromatic leukodystrophy. This would be the first such study in China. All eight exons and exon-intron boundaries of the arylsulfatase A gene (ARSA) were amplified with polymerase chain reaction, which was followed by direct DNA sequencing. Patient 1 exhibited a homozygous mutation at c.954G>A (p.W318X) in exon 5. Patient 2 exhibited compound heterozygous mutations, identified as one allele with the c.862C>T (p.R288C) missense mutation in exon 5 and the other allele with the c.1338dupC frameshift mutation in exon 8. Patient 3 exhibited only a c.179_180dupCA frameshift mutation in exon 1 in one allele. Patients 4 and 5 exhibited identical compound heterozygous mutations, identified as one allele with the c.296G>T (p.G99V) missense mutation and the other allele with the c.251G>A (p.R84Q) missense mutation in exon 2. Six DNA variants of the arylsulfatase A gene were identified: two novel frameshift mutations (c.179_180dupCA and c.1338dupC), one known nonsense mutation (p.W318X), and three known missense mutations (p.R84Q, p.G99V, and p.R288C).

Metachromatic leukodystrophy in the Navajo: fallout of the American-Indian wars of the nineteenth century.

Our aim was to determine if the high frequency of metachromatic leukodystrophy (MLD) in Navajo Indians of the Southwestern United States is the result of a "genetic bottleneck" that occurred in the mid 19th century. Navajo Nation, Indian Health Service, and other national databases were queried for Native American patients with MLD. Pedigrees, including birth location, were established by interviewing relatives. We found that cases of MLD and their ancestors are clustered in a portion of the western Navajo Nation to which a small number of Navajo fled after armed conflict with the United States Army in the 1860s. The observed incidence of MLD on the western Navajo Nation is 1/2,520 live births, with an estimated carrier frequency of 1/25 to 1/50. No cases were observed in the eastern part of the Navajo Nation over a period of 18 years (60,000 births). The high incidence of MLD in the western Navajo Nation appears to be the result of a genetic bottleneck and probable founder effect from the mid 19th century: This mechanism may also explain the high incidence of a number of other unique, heritable disorders among the Navajo. The history of the Navajo may also be relevant to other American Indian and Alaskan Native groups that have undergone severe population reduction since the arrival of Europeans in North America.

Late infantile metachromatic leukodystrophy in Israel.

Metachromatic Leukodystrophy (MLD) is a neurodegenerative disease in which the lysosomal enzyme, Aryl sulfatase A (ARSA) is deficient. The disease is inherited as an autosomal recessive trait and its frequency is estimated to be 1/40,000 live births. The gene of ARSA has been cloned and up to now eight mutations causing MLD have been reported. Another mutation, PD, leads to the deficiency of the enzyme in vitro (pseudodeficiency) without any known clinical effect. The PD mutation is frequent in all populations. In Israel, late infantile MLD was found to be very frequent in a small Jewish isolate, the Habbanite Jews (1/75 live births). The molecular analysis demonstrated that in the Habbanite population, the mutation occurred on an allele with the PD mutation. The loss of ARSA activity is due to a point mutation C > T leading to a change of proline to leucine. MLD is also frequent among Moslem Arabs in Jerusalem. The mutation is a transition G > A destroying the splice donor site of exon 2. This mutation has been reported in patients with the late infantile MLD from different ethnic groups. The Christian Arabs in Israel also have a high incidence of the disease (1/10,000 live births); the mutation in this population is still unknown. Knowledge of the different mutations causing MLD in these defined populations will allow a carrier screening program to be carried out and prevent the birth of additional affected children.