Genomics and cure: understanding narratives of patients with Duchenne muscular dystrophy in Japan.

Globally, genomics research is expected to enhance the health of patients with intractable diseases such as Duchenne muscular dystrophy (DMD). But how do patients perceive medical and scientific attempts at creating drugs and finding cure, and why? Since the 1990s, a number of clinical trials for patients of DMD have been organized. Among them are a gene therapy and exon skipping, and they indicate the possibility of finding therapies for DMD patients. Since 2011, Japanese medical institutions have been participating in Global Clinical Trials so that Japanese DMD patients can have access to them once developed. Despite ongoing global clinical trials, however, field research shows that the DMD patients the author encountered were neither enthusiastic nor well informed about gene therapies developed in Japan or elsewhere. Why not? The author observed that the desire for a cure among DMD patients is not self-evident, but is framed by sociocultural conditions surrounding the patients, the local history of discrimination against genetic disorders, and the way care is organised. These factors further interplay with physical and mental conditions particular to DMD, affecting patients' desire for a cure. This paper discusses the perception of genomics research and the possibility of a cure of DMD patients the author encountered in Japan, indicating that such perceptions are a result of the deeply-related interactions of the conditions in which patients live. Finally, the author suggests how commonly held views of patients and patients' desire for cure need to be nuanced in genomic medicine. Data in this paper were collected between April and July 2014, and between 1996 and 2005 in Japan.

Variations in Duchenne muscular dystrophy course in a multi-ethnic UK population: potential influence of socio-economic factors.

AIM: To explore variation in clinical course and steroid treatment in Duchenne muscular dystrophy (DMD) by ethnic origin and socio-economic status. METHOD: In this longitudinal cohort study, clinical outcome was defined as age at loss of ambulation (LOA). Ages are presented as months for accurate calculation. Steroid use was reviewed against national guidelines. Kaplan-Meier survival analysis was used to determine probabilities over time of LOA. Log-rank test was used to evaluate comparisons between ethnic and socio-economic groups. RESULTS: From 2005 to 2014, 71 children were newly diagnosed with DMD. Complete data were available on 69, including 33 of white British heritage and 23 of South Asian heritage. Mean age at diagnosis (without known family history) was 45.7 months; white British ethnicity 42.1 months (range 14-86mo), South Asian ethnicity 50.2 months (range 5-98mo). Twenty-four males lost ambulation. Those of South Asian heritage lost ambulation earlier (mean LOA 105.8mo [8y 10mo]) than those of white British heritage (mean LOA 117.8mo [9y 10mo]): log-rank test score 0.012 (p<0.05). Those most deprived did worse: mean age at LOA 130.0 months (10y 10mo) for the top 20 per cent and 102.5 months (8y 6mo) in the lower 20 per cent: log-rank test score 0.035 (p<0.05). The most socially deprived were diagnosed earlier and started steroids earlier. Of those of South Asian heritage, 18 per cent declined steroids, compared with 9 per cent of white British heritage. Also, 44 per cent of those of South Asian heritage stopped steroids compared with 17 per cent of those of white British heritage. INTERPRETATION: Patients from South Asian and deprived backgrounds had earlier LOA. Genetic disease modifiers are likely to be implicated, but social and cultural factors influence access to treatment.

Multiplex Ligation-Dependent Probe Amplification in X-linked Recessive Muscular Dystrophy in Korean Subjects.

PURPOSE: Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are similar genetic disorders whose patterns of mutation and disease phenotypes might be expected to show differences among different countries. We analyzed multiplex ligation-dependent probe amplification (MLPA) data in a large number of Korean patients with DMD/BMD. MATERIALS AND METHODS: We obtained 130 positive MLPA results (86 DMD, 27 BMD, and 17 female carriers) from 272 candidates (237 clinically suspected patients and 35 possible female carriers) who took part in this study. We analyzed the mutation patterns among 113 patients diagnosed by MLPA and calculated deletion/duplication percentages from a total of 128 patients, including 15 patients who were diagnosed using methods other than MLPA. We also analyzed hot spot locations among the 130 MLPA-positive results. RESULTS: Most mutations were detected in a central hot spot region between exons 44 and 55 (80 samples, 60.6%). Unlike previous reports, a second frequently observed hot spot near the 5'-end was not distinctive. MLPA detected deletions in specific exons in 92 patients with DMD/BMD (71.8%) and duplications in 21 patients (16.4%). CONCLUSION: Our MLPA study of a large number of Korean patients with DMD/BMD identified the most frequent mutation hot spot, as well as a unique hot spot pattern. DMD gene mutation patterns do not appear to show significant ethnic differences.

Genetic modifiers of ambulation in the Cooperative International Neuromuscular Research Group Duchenne Natural History Study.

OBJECTIVE: We studied the effects of LTBP4 and SPP1 polymorphisms on age at loss of ambulation (LoA) in a multiethnic Duchenne muscular dystrophy (DMD) cohort. METHODS: We genotyped SPP1 rs28357094 and LTBP4 haplotype in 283 of 340 participants in the Cooperative International Neuromuscular Research Group Duchenne Natural History Study (CINRG-DNHS). Median ages at LoA were compared by Kaplan-Meier analysis and log-rank test. We controlled polymorphism analyses for concurrent effects of glucocorticoid corticosteroid (GC) treatment (time-varying Cox regression) and for population stratification (multidimensional scaling of genome-wide markers). RESULTS: Hispanic and South Asian participants (n = 18, 41) lost ambulation 2.7 and 2 years earlier than Caucasian subjects (p = 0.003, <0.001). The TG/GG genotype at SPP1 rs28357094 was associated to 1.2-year-earlier median LoA (p = 0.048). This difference was greater (1.9 years, p = 0.038) in GC-treated participants, whereas no difference was observed in untreated subjects. Cox regression confirmed a significant effect of SPP1 genotype in GC-treated participants (hazard ratio = 1.61, p = 0.016). LTBP4 genotype showed a direction of association with age at LoA as previously reported, but it was not statistically significant. After controlling for population stratification, we confirmed a strong effect of LTBP4 genotype in Caucasians (2.4 years, p = 0.024). Median age at LoA with the protective LTBP4 genotype in this cohort was 15.0 years, 16.0 for those who were treated with GC. INTERPRETATION: SPP1 rs28357094 acts as a pharmacodynamic biomarker of GC response, and LTBP4 haplotype modifies age at LoA in the CINRG-DNHS cohort. Adjustment for GC treatment and population stratification appears crucial in assessing genetic modifiers in DMD.

Prevalence of Duchenne and Becker muscular dystrophies in the United States.

OBJECTIVE: To estimate prevalence of childhood-onset Duchenne and Becker muscular dystrophies (DBMD) in 6 sites in the United States by race/ethnicity and phenotype (Duchenne muscular dystrophy [DMD] or Becker muscular dystrophy [BMD]). METHODS: In 2002, the Centers for Disease Control and Prevention established the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) to conduct longitudinal, population-based surveillance and research of DBMD in the United States. Six sites conducted active, multiple-source case finding and record abstraction to identify MD STARnet cases born January 1982 to December 2011. We used cross-sectional analyses to estimate prevalence of DBMD per 10 000 boys, ages 5 to 9 years, for 4 quinquennia (1991-1995, 1996-2000, 2001-2005, and 2006-2010) and prevalence per 10 000 male individuals, ages 5 to 24 years, in 2010. Prevalence was also estimated by race/ethnicity and phenotype. RESULTS: Overall, 649 cases resided in an MD STARnet site during ≥1 quinquennia. Prevalence estimates per 10 000 boys, ages 5 to 9 years, were 1.93, 2.05, 2.04, and 1.51, respectively, for 1991-1995, 1996-2000, 2001-2005, and 2006-2010. Prevalence tended to be higher for Hispanic individuals than non-Hispanic white or black individuals, and higher for DMD than BMD. In 2010, prevalence of DBMD was 1.38 per 10 000 male individuals, ages 5 to 24 years. CONCLUSIONS: We present population-based prevalence estimates for DBMD in 6 US sites. Prevalence differed by race/ethnicity, suggesting potential cultural and socioeconomic influences in the diagnosis of DBMD. Prevalence also was higher for DMD than BMD. Continued longitudinal surveillance will permit us to examine racial/ethnic and socioeconomic differences in treatment and outcomes for MD STARnet cases.

Development of a comprehensive real-time PCR assay for dystrophin gene analysis and prenatal diagnosis of Chinese families.

BACKGROUND: To develop a comprehensive method to analyze deletions or duplications of the dystrophin gene in both patients and carriers of Duchenne muscular dystrophy (DMD), likewise applied to prenatal diagnosis. METHODS: A total of thirty Chinese families were recruited, composed of 29 DMD affected males and 38 female relatives containing four pregnant women. Deletions were previously screened by multiplex PCR. A comprehensive real-time PCR assay using SYBR Green I dye was performed for the initial detection of duplications in patients with a seven-exon primer set, carrier detection for female relatives and prenatal diagnosis for the 4 of them. The results were later confirmed by multiple ligation-dependent probe amplification (MLPA) and linkage analysis. RESULTS: Three out of 4 duplications were first discovered by real-time PCR. Carrier status was ascertained in 22 and rejected in the remaining sixteen female relatives. Furthermore, 4 fetuses were diagnosed as two normal females, one normal male and one female carrier, respectively. CONCLUSIONS: Our real-time PCR assay is useful in duplication screen with a detection rate of >70%, as well as rapid and reliable in both carrier detection and prenatal diagnosis of DMD families with known deletions and duplications.

Coexistence of two distinct intragenic dystrophin deletions in two maternal cousins with Duchenne Muscular Dystrophy.

The identification of two independent mutations is rarely described between affected members of the same family with Duchenne Muscular Dystrophy. This study reports the presence of two distinct intragenic dystrophin deletions in a Turkish family. Exon 54 deletion was identified originally in the proband, whereas his maternal cousin had deletions of exons 43-50 in the dystrophin gene. As indicated, only the mother of the proband was identified as exon 54 deletion carrier however, the proband's cousin was detected as a sporadic case. These molecular genetic data reveal an interesting and novel mixture, in the same family, of both mutations of the same gene.

Disparities in the diagnostic process of Duchenne and Becker muscular dystrophy.

PURPOSE: To determine whether sociodemographic factors are associated with delays at specific steps in the diagnostic process of Duchenne and Becker muscular dystrophy. METHODS: We examined abstracted medical records for 540 males from population-based surveillance sites in Arizona, Colorado, Georgia, Iowa, and western New York. We used linear regressions to model the association of three sociodemographic characteristics with age at initial medical evaluation, first creatine kinase measurement, and earliest DNA analysis while controlling for changes in the diagnostic process over time. The analytical dataset included 375 males with information on family history of Duchenne and Becker muscular dystrophy, neighborhood poverty levels, and race/ethnicity. RESULTS: Black and Hispanic race/ethnicity predicted older ages at initial evaluation, creatine kinase measurement, and DNA testing (P < 0.05). A positive family history of Duchenne and Becker muscular dystrophy predicted younger ages at initial evaluation, creatine kinase measurement and DNA testing (P < 0.001). Higher neighborhood poverty was associated with earlier ages of evaluation (P < 0.05). CONCLUSIONS: Racial and ethnic disparities in the diagnostic process for Duchenne and Becker muscular dystrophy are evident even after adjustment for family history of Duchenne and Becker muscular dystrophy and changes in the diagnostic process over time. Black and Hispanic children are initially evaluated at older ages than white children, and the gap widens at later steps in the diagnostic process.

A pilot study to determine whether health care professionals perceive stigma in heterozygote carrier identification and disclosure decisions.

We conducted an empirical pilot study to assess the attitudes of health care professionals (HCPs) to the personal identification of heterozygote carrier status for two autosomal recessive conditions (cystic fibrosis and a hemoglobinopathy) and for an X-linked disorder (Duchenne muscular dystrophy) using the Health Orientation Scale (HOS) and a modified HIV Stigma Scale. Attitudes towards carrier identification of children were also assessed. Three hundred and ten of 742 (42%) eligible HCPs fully or partly completed the survey. As measured with the HOS and the modified HIV scale, respondents had a more negative reaction to the hypothetical discovery of being a carrier for an autosomal recessive genetic condition that was less likely given their self-identified ancestry. Female respondents had a more negative reaction on both scales to being a carrier for an X-linked disorder than men thought their partners would feel. However, the differences found on the HOS and modified HIV scale are small and their clinical relevance unknown. Fifty-seven percent of respondents agreed that parents should tell their children to keep their carrier status private with many (44%) agreeing that children who learn that they are carriers may suffer from a decrease in self-esteem. The vast majority of respondents would inform immediate family members and HCPs of their carrier status, but would be unlikely to share this information with neighbors or employers. Further study is needed to develop a heterozygote genetic carrier stigma scale.

Dystrophin gene analysis in Hungarian Duchenne/Becker muscular dystrophy families - detection of carrier status in symptomatic and asymptomatic female relatives.

A comprehensive study of the Hungarian Duchenne/Becker muscular dystrophy (DMD/BMD) families is presented. Deletions in the hot spots regions were identified by multiplex PCR, whereas rare mutations were detected by Southern blot and multiplex ligation-dependent probe amplification (MLPA) techniques. DMD/BMD disease was confirmed and exact deletion borders were determined in 19 out of 135 affected males using multiplex PCR. Additional exons involved as well as rare exon deletions were identified by MLPA in 71 male patients, whereas duplications were observed in seven patients. In two DMD patients, the entire dystrophin gene and adjacent genes were deleted. Out of the 95 female relatives, 41 proved to be carriers, including three manifesting carrier females. Using MLPA method, a large portion of the Hungarian DMD/BMD patients and their female relatives were exactly genotyped. For the first time, the incidence and prevalence of asymptomatic and symptomatic female carriers in Hungary was estimated.

Intragenic deletions in the dystrophin gene in 211 Pakistani Duchenne muscular dystrophy patients.

BACKGROUND: Deletions of single or multiple exonic regions within the dystrophin gene can be detected using current molecular methods in approximately 65% of the patients with X-linked recessive neuromuscular disorder, Duchenne/Becker muscular dystrophy (DMD/BMD). Population-based variations in frequency and distribution of dystrophin gene deletions have been reported in DMD/BMD patients. In the present study, the first in the Pakistani population, frequency and distribution of deletions of 18 exons clustered in two hot spots within the dystrophin gene in 211 unrelated DMD patients were analyzed. METHODS: A total of 211 patients suffering from DMD were ascertained, and intragenic deletions within the dystrophin gene were detected on polymerase chain reaction amplification of the genomic DNA using 18 primer sets clustered within two major deletion hot spots. lovd v.1.1.0 software from the Leiden Muscular Dystrophy website has been used to predict in-frame and out-of-frame deletions. RESULTS: Intragenic deletions were detected in 86 patients (40.75%): 35 patients (40.69%) had deletions within the proximal hot spot, and 51 patients (59.30%) had deletions confined to the distal deletion hot spot of the dystrophin gene. The most frequently deleted exons were 50, 6, 47, 13 and 52 with deletion frequencies of 15.11%, 12.79%, 10.46%, 8.13%, and 4.65%, respectively. lovd v.1.1.0 predicted out-of-frame deletions in 67 DMD patients and in-frame deletions in 19 DMD patients. CONCLUSIONS: The observed proportion of intragenic deletions in the Pakistani population is relatively low, which is comparable with most of the Asian data. Also, deletions in 67 patients (77.9%) are in agreement with the frame-shift rule.

Patterns of dystrophin gene deletion in Egyptian Duchenne/Becker muscular dystrophy patients.

Large variations in the proportion of intragenic deletion in the dystrophin gene have been observed in different populations. Although dystrophin gene deletion was extensively studied all over the world, only few studies were done on Egyptian population and there was no account on the dystrophin gene duplication. In this study, we present our results on the pattern of deletion of the dystrophin gene together with the usage of quantitative polymerase chain reaction (PCR) as a method for duplication analysis within the dystrophin gene in Egyptian patients. Forty one Duchene/Becker muscular dystrophy patients were included in this study. The diagnosis was based on detailed clinical assessment, serum creatine kinase (CK) level, neurophysiologic study and muscle biopsy for histopathological analysis. DNA was extracted from ten milliliter peripheral blood according to basic protocol, and multiplex polymerase chain reaction for dystrophin gene using both Chamberlin and Beggs sets of primers amplifying eighteen exons covering the two main dystrophin gene hot spots. In addition primers from Abbs set were used when it was necessary to check the exon borders. DNA from cases with no detectable deletion was analyzed for dystrophin gene duplication using quantitative PCR technique. We had a percentage of 61.1% deletion which is higher than data from previous Egyptian studies and most of the deletion was localized in the major hotspot region between exons 44 and 52 and we had 5% of the cases with duplication. Our results were compared with previous studies from Egypt and with studies from different populations especially with data recorded in the Middle East and North Africa.

[Relationship of phenotype with type of deletion of dystrophin gene].

OBJECTIVE: To detect the distribution characteristics of dystrophin gene deletions in the northeastern of China and the relationship of severity with type of deletion. METHODS: To screen deletion distribution of 124 DMD/BMD patients via multiplex PCR, male high-risk fetuses were detected deletion by the same method. RESULTS: The deletion frequency was 49%. Deletions located in the regions of exons 45 - 53 and exons 8 - 19 were 41 (67%) and 13 (21%) cases respectively, and in 5 (8%) cases deletions were scattered over both regions, still 2 cases (3%) were checked up deletions lying in exons 34 and 43; there were 9 cases of in-frame deletions and 49 frameshift mutations in all deletions; of 30 high-risk fetuses 10 male ones were screened deletions, who had the same deletion-segments as their probands. CONCLUSIONS: The distribution of dystrophin gene deletions in the northeastern of China cluster mainly in two hot-spots, neighboring regions of exon 8 might be a real deletion "hot spot" in this region; the phenotype is associated with the type of gene deletion, the phenotype is BMD when in-frame deletions occur; severe DMD when frameshift mutations occur. Multiplex PCR method provides the short-cuts for detecting patients and making prenatal gene diagnosis.

Dystrophin gene deletions in South Indian Duchenne muscular dystrophy patients.

66 unrelated patients from Southern India with Duchenne Muscular Dystrophy (DMD) were studied for intragenic deletion in 18 exons and Pm region of the DMD gene using multiplex PCR. Of these 41 (62.1%) showed intragenic deletions. 78% of the deletions were located at the distal hotspot region (44-55 exons) and 22% of the deletions were located at the proximal region (exon 2-19). Exon 50 is most frequently deleted. Deletions in isolated cases were significantly more compared to familial cases. The lower incidence reported from South India compared to North India, is suggestive of variations in the Southern and Northern population.

Deletion mutations in the dystrophin gene of Saudi patients with Duchenne and Becker muscular dystrophy.

OBJECTIVE: The deletion in the dystrophin gene has been reported for many ethnic groups, but until now the mutations in this gene have not been thoroughly investigated in Saudi patients with Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). We examined the deletion pattern in the dystrophin gene of the Saudi patients applying multiplex-polymerase chain reaction (PCR). The aim of this study is to describe the outcome of our initial effort to identify mutations in the dystrophin gene in a representative group of Saudi patients with DMD and BMD. METHODS: Genomic deoxyribose nucleic acid was isolated from 41 patients with DMD and BMD (27 patients confirmed by muscle biopsy and 14 patients with clinical suspicion), 3 patients with limb girdle muscular dystrophy, 12 male relatives of the patients, and 5 healthy Saudi volunteers. A total of 25 exons around the deletion prone regions (hot spots) of the dystrophin gene were amplified. The study was carried out at the King Fahad National Guard Hospital, Riyadh, Kingdom of Saudi Arabia between 2000 and 2002. RESULTS: The deletion of one or more exons was found in 21 of 27 DMD and BMD patients confirmed by muscle biopsy. The deletion in the gene was detected in 5 of 14 patients with DMD diagnosis, but not confirmed by dystrophin staining of muscle biopsy. No deletion in the dystrophin gene was detected in control Saudi volunteers, the limb girdle dystrophy patients, and the relatives of patients, as expected. CONCLUSION: The present study suggests that intragenic dystrophin gene deletions occur with the same frequency in Saudi patients compared with other ethnic groups. The PCR-based deletion analysis provides a reasonable first step in the diagnostic care of Saudi patients who may be afflicted with DMD and BMD.

Patterns of deletions and the distribution of breakpoints in the dystrophin gene in Czech patients with Duchenne and Becker muscular dystrophy (statistical comparison with results from several other countries).

Deletion pattern analysis of the dystrophin gene was performed in 115 unrelated Czech patients with Duchenne and Becker muscular dystrophy. In 50 patients (43.5% of the analysed patients) exon deletions were detected by routinely performed multiplex PCR for 18 selected exons and for the area of musclespecific promoter of the dystrophin gene. All startpoints and endpoints of deletions (100 breakpoints) were detected using PCRs for another 29 exon areas of the dystrophin gene (altogether primers for 47 different exons were used). Most of the breakpoints were found in introns 44 (16% of breakpoints), 47 (14%) and 50 (8%). The comparison of distributions of breakpoints in the area of the main hot spot of the dystrophin gene (introns 43-52) was made (chi 2 test in a contingency table) in six different populations from the Czech Republic, Bulgaria, Hungary, Italy, Turkey and India. In compared populations, statistically significant differences were found by the pooled test. No significant difference between the Czech population and other studied populations was found by pair comparisons. On the other hand, pair comparisons revealed significant differences between populations from Bulgaria and Hungary, Bulgaria and Turkey, Hungary and Italy. The results of the presented study support the theory suggested by other authors that specific differences in intron sequences of the dystrophin gene can exist between different populations, possibly as a result of a genetic drift.

Deletion pattern in the dystrophin gene in Turks and a comparison with Europeans and Indians.

Patterns of dystrophin gene deletions in DMD/BMD patients were compared in four populations: Turks (n = 146 deletions), Europeans (n = 838), North Indians (n = 89), and Indians from all over India (n = 103). Statistical tests revealed that there are differences in the proportions of small deletions. In contrast, the distribution of deletion breakpoints and the frequencies of specific deletions commonly observed in the four populations are not significantly different. The variations strongly suggest that sequence differences exist in the introns, and the differences are in agreement with genetic distances among populations. The similarities suggest that some intronic sequences have been conserved and that those will trigger recurrent deletions, since it is unlikely that gene flow would disperse the deleted chromosomes, which vanish from the gene pool in a few generations.