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.

Fatty acid oxidation defects presenting as primary myopathy and prominent dropped head syndrome.

Fatty acid oxidation disorders presenting as primary myopathy is relatively rare and also diagnostically challenging. Its association with "dropped head syndrome" is reported till date in single cases of carnitine deficiency and multiple acyl CoA dehydrogenase deficiency (MADD).We studied nineteen cases of primary progressive myopathy confirmed to have fatty acid oxidation defects by Tandem Mass Spectrometry. The detailed clinical, muscle histopathology, tandem mass spectrometry and muscle magnetic resonance imaging (MRI) findings are presented here. The fatty acid oxidation defects identified were sub-grouped into: medium chain acyl CoA dehydrogenase deficiency (MCAD) = 4; very long chain acyl CoA dehydrogenase deficiency (VLCAD) = 7; MADD = 6; carnitine uptake defect and short chain acyl CoA dehydrogenase (SCAD) deficiency = 1 each. The age at onset for MCAD, VLCAD and MADD ranged from 11.5 to 15, 8 to 17 and 10 to 38 years respectively. The patients with carnitine uptake defect and SCAD had onset at 29 and 15 years of age. The dominant symptoms were exertion induced myalgia and progressive proximal limb weakness in all. 12/19 (63.2%) had classical dropped head syndrome. Ptosis and bulbar weakness were present in a few cases. This study emphasizes that fatty acid oxidation disorders presenting as primary myopathy are probably under diagnosed and should be entertained in the differential diagnosis of acute or chronic limb girdle syndromes. Hitherto, unreported we describe "dropped head syndrome" as a prominent phenomenon in MCAD and VLCAD. The presence of ptosis and bulbar weakness in fatty acid oxidation defects expands the clinical spectrum.

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.