Neuro-Cardio-Autonomic Modulations in Children with Duchenne Muscular Dystrophy.

BACKGROUND AND OBJECTIVE: Duchenne muscular dystrophy (DMD) is a degenerative X-linked muscle disease. Death frequently results from complications in cardiopulmonary systems. Preclinical/early diagnosis of cardiac autonomic abnormalities may aid initiate cardioprotective therapy and enhance prognosis. METHODS: A cross sectional, prospective study of 38 DMD boys compared with 37 age-matched healthy controls was conducted. Lead II electrocardiography and beat-to-beat blood pressure were recorded to assess heart rate variability (HRV), blood pressure variability (BPV), and baroreceptor sensitivity (BRS) in a standardized environment. Data were analysed and correlated with disease severity and genotype. RESULTS: In the DMD group, the median age at assessment was 8 years [IQR 7-9 years], the median age at disease onset was 3 years [IQR, 2-6 years], and the mean duration of illness was 4 years [IQR, 2.5-5]. DNA sequencing showed deletions in 34/38 (89.5 %) and duplications in 4/38 (10.5%) patients. The median heart rate in DMD children was significantly higher [101.19 (Range, 94.71-108.49)] /min compared to controls [81 (Range, 76.2-92.76)] /min (p < 0.05). All the assessed HRV and BPV parameters were significantly impaired in DMD cases except for the coefficient of variance of systolic blood pressure. Further, BRS parameters were also significantly reduced in DMD, excluding alpha-LF. A positive correlation was found between alpha HF with age at onset and duration of illness. CONCLUSION: This study demonstrates a distinct early impairment of neuro-cardio-autonomic regulation in DMD. Simple yet effective non-invasive techniques such as HRV, BPV, and BRS may help identify cardiac dysfunction in a pre-clinical state, paving the way for early cardio-protective therapies and limiting disease progression in DMD patients.

Utility of Immunohistochemistry and Western Blot in Profiling Clinically Suspected Cases of Congenital Muscular Dystrophy.

OBJECTIVE: Immunocharacterization of congenital muscular dystrophy (CMD) to determine the frequency of various subtypes in a large Indian Cohort. MATERIALS AND METHODS: This retrospective (2014-2017) study was carried on muscle biopsies of clinically suspected cases of CMD with histological evidence of dystrophy/myopathic features. Immunohistochemistry (IHC) to antibodies against laminin (α2, α5,ß1,γ1), Collagen-VI (A1,2,3), and Western blot (WB) for α-dystroglycan and POMT1 was performed. RESULTS: The study included 57 cases, of which 15 cases (26.3%) had mean age at presentation of 3.5 years, M: F = 1.5:1, elevated creatinine kinase (CK) (mean 1657 U/L), global developmental delay, multiple contractures, abnormal facies, white matter hyperintensities and showed laminin-α2 deficiency (Merosin deficient CMD). In addition, secondary reduction in laminin-ß1, over-expression of laminin-α5, and preserved laminin-γ1 was noted. Ullrich CMD constituted 11/57 cases (19.2%) with mean age at presentation of 5.3 years, M: F = 1.2:1 and normal CK. They presented with proximal muscle weakness, soft velvety palms and soles, contractures, and joint hyperextensibility. Collagen-VI (A1,2,3) showed either complete (n = 3) or sarcolemmal specific (n = 8) loss of staining. Out of the remaining 31 cases, WB for α-dystroglycan was performed in 17 cases which showed deficiency in seven (12.3%). Three of these in addition revealed secondary partial loss of laminin-α2. WB for POMT1 showed deficiency in a single case clinically diagnosed Walker-Warburg syndrome, who presented with seizures and classical features of pachygyria, lissencephaly, and cerebellar cyst on MRI. Twenty-four cases (42.2%) remained uncharacterized and need genetic evaluation. CONCLUSION: The study helped in characterizing 57.8% of the proband. Immunotyping helps to direct mutational analysis for targeted genes and offers a potential route for prenatal diagnosis.

Mutation pattern in 606 Duchenne muscular dystrophy children with a comparison between familial and non-familial forms: a study in an Indian large single-center cohort.

INTRODUCTION: Duchenne muscular dystrophy (DMD) is induced by a wide spectrum of mutations such as exon deletions, duplications and small mutations in the dystrophin gene. This is the first study on the mutational spectrum in a cohort of DMD children from India, with an emphasis to compare the mutations in familial and sporadic forms. RESULTS: Multiplex ligation-dependent probe amplification (MLPA) and next-generation sequencing (NGS) identified 525 and 70 cases of DMD, respectively, while 11 cases showed absent dystrophin staining with no mutations detected. Families with two or more affected males contributed to 12% of the entire cohort. The mutations comprised of exonic deletions in 492/606 (81.2%), duplications in 33/606 (5.4%) and small mutations (point mutations and INDELs) in 70/606 (11.5%) cases. MLPA identified significantly more larger mutations in sporadic (88.2%) than in familial cases (75.3%). The mutations in NGS were: [nonsense = 40 (57.1%); frameshift = 17 (24.3%); splice variant = 12 (17.1%)]. Nonsense mutations were more common in familial than in sporadic cases: 17.8% vs 10.7%. The familial group reported an earlier onset of disease (2.8 ± 1.7 years) as compared to sporadic cases (3.8 ± 1.6 years). CONCLUSION: MLPA could identify mutations in a high percentage of our DMD children. The preponderance of small mutations was noted to be distinctly higher in the familial group. Intriguingly, the familial form of DMD formed a small percentage of the entire cohort. The reasons could be increasing awareness among parents and physicians with early identification of DMD cases, genetic counseling and prenatal testing.

Natural history of a cohort of Duchenne muscular dystrophy children seen between 1998 and 2014: An observational study from South India.

BACKGROUND: Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy. There are no large studies describing its natural course from India. MATERIALS AND METHODS: Immunohistochemically/genetically confirmed DMD patients diagnosed between 1998 and 2014 were ambispectively included. The main aim was to study the natural course of motor milestones, i.e., age at onset of wheelchair status, bedbound state, and age at death, which were considered as primary outcome measures. We also correlated the DMD genotype with the motor milestones and other phenotypic features. RESULTS: A total of 500 DMD patients were included and 275 participated in the study. The mean age at symptom onset was 3.7 ± 1.9 years, mean age at presentation was 8.1 ± 2.5 years, and mean duration of illness was 4.4 ± 2.6 years. On following them over 15 years, 155 (56.4%) had attained at least one of the primary outcome measures. Wheelchair status was attained in 124 (45.1%) [mean age: 10.4 ± 1.6 years] and bedbound state in 24 (8.7%; mean age: 11.8 ± 2.2 years) patients. Seven patients (2.6%) died during the follow-up period (mean age: 15.2 ± 2.4 years). There was no significant impact of the genotypic or phenotypic features on the primary outcome. CONCLUSION: The pattern of major motor milestones (primary outcome measures) in this large cohort is comparable with that of the Western population despite variability in medical care. The genotypic pattern was also similar to other large studies, which suggests that DMD is a more homogeneous disorder with limited ethnic variability in its geno-phenotypic expression.

Duchenne Muscular Dystrophy and Becker Muscular Dystrophy Confirmed by Multiplex Ligation-Dependent Probe Amplification: Genotype-Phenotype Correlation in a Large Cohort.

BACKGROUND AND PURPOSE: Studies of cases of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) confirmed by multiplex ligation-dependent probe amplification (MLPA) have determined the clinical characteristics, genotype, and relations between the reading frame and phenotype for different countries. This is the first such study from India. METHODS: A retrospective genotype-phenotype analysis of 317 MLPA-confirmed patients with DMD or BMD who visited the neuromuscular clinic of a quaternary referral center in southern India. RESULTS: The 317 patients comprised 279 cases of DMD (88%), 32 of BMD (10.1%), and 6 of intermediate phenotype (1.9%). Deletions accounted for 91.8% of cases, with duplications causing the remaining 8.2%. There were 254 cases of DMD (91%) with deletions and 25 (9%) due to duplications, and 31 cases (96.8%) of BMD with deletions and 1 (3.2%) due to duplication. All six cases of intermediate type were due to deletions. The most-common mutation was a single-exon deletion. Deletions of six or fewer exons constituted 68.8% of cases. The deletion of exon 50 was the most common. The reading-frame rule held in 90% of DMD and 94% of BMD cases. A tendency toward a lower IQ and earlier wheelchair dependence was observed with distal exon deletions, though a significant correlation was not found. CONCLUSIONS: The reading-frame rule held in 90% to 94% of children, which is consistent with reports from other parts of the world. However, testing by MLPA is a limitation, and advanced sequencing methods including analysis of the structure of mutant dystrophin is needed for more-accurate assessments of the genotype-phenotype correlation.

Muscle MRI in Duchenne muscular dystrophy: Evidence of a distinctive pattern.

The purpose of this study was to describe the pattern of muscle involvement using MRI findings and correlate with functional as well as muscle strength measurements. Fifty genetically confirmed DMD children with a mean age of 7.6 ± 2.8 (4-15 years) underwent muscle MRI and qualitative assessment was done for muscle changes using Mercuri staging for fibro-fatty replacement on T1 sequence and Borsato score for myoedema on STIR sequence. Detailed phenotypic characterisation was done with Manual muscle testing (modified MRC grading) and Muscular Dystrophy Functional Rating Scale (MDFRS). Mercuri scoring showed severe fibro-fatty changes in Gluteus medius, minimus and Adductor magnus followed by moderate to severe changes in Gluteus maximus and Quadriceps muscles. Total sparing of Gracilis, Sartorius and Semimembranosus muscles was observed. Superficial posterior and lateral leg muscles were preferentially involved with sparing of deep posterior and anterior leg muscles. Myoedema showed significant inverse correlation with fatty infiltration in thigh muscles. Similarly, significant inverse correlation was observed between Mercuri scores and MRC grading as well as MDFRS scores. A direct linear correlation was observed between duration of illness and fibro-fatty changes in piriformis, quadriceps and superficial posterior leg muscles. There was no correlation between MRI findings and genotypic characteristics. However, this specific pattern of muscle involvement in MRI could aid in proceeding for genetic testing when clinical suspicion is high, thus reducing the need for muscle biopsy. Fibro fatty infiltration as measured by Mercuri scoring can be a useful marker for assessing the disease severity and progression.