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Spectrum of floppy children in Indian scenario
1Department of Pediatrics, All India Institute of Medical Sciences, New Delhi 110 029, India.
Insights
Spinal muscular atrophy (SMA) is the most frequent cause of floppy infants. Further research is needed to confirm the low rate of survival motor neuron (SMNT) gene deletion found in SMA cases.
Area of Science:
- Neurology
- Genetics
- Pediatrics
Background:
- Floppy infant syndrome presents a diagnostic challenge.
- Spinal muscular atrophy (SMA) is a significant cause of infantile hypotonia.
Purpose of the Study:
- To investigate the clinical characteristics of infants with paralytic hypotonia.
- To determine the frequency of exon 7 deletion in the survival motor neuron (SMNT) gene in spinal muscular atrophy (SMA) cases.
Main Methods:
- A descriptive study was conducted on 70 infants under 13 years with paralytic hypotonia.
- Investigations included clinical evaluation, serum creatine phosphokinase, electrophysiological studies, muscle biopsy, and SMNT gene deletion analysis via PCR.
Main Results:
- Spinal muscular atrophy (SMA) was diagnosed in 37 patients, followed by other myopathies and neuropathies.
- Electromyography (EMG) showed 80.6% sensitivity for neurogenic and 75% for muscle disease.
- Exon 7 deletion of the SMNT gene was identified in only 50% of confirmed SMA cases.
Conclusions:
- Spinal muscular atrophy (SMA) is the predominant cause of floppy infants.
- The observed low frequency of SMNT gene deletion necessitates further investigation and validation.
Objective:
To study the clinical profile of paralytic floppy infants undertaking available investigations and detect the frequency of exon7 of survival motor neuron (SMNT) gene deletion among the spinal muscular atrophy (SMA) cases.
Design:
Descriptive study.
Setting:
Tertiary care teaching hospital.
Subjects:
70 paralytic floppy infants (40 males/30 females) with age less than 13 years were included in the study. Exclusion criteria included central hypotonia of any cause. Detailed clinical evaluation was done followed by serum creatine phosphokinase levels, electrophysiological studies, muscle biopsy including immunohistochemistry and electron microscopy. Exon7 of SMNT gene deletion studies was done by PCR.
Results:
Final diagnosis of SMA was assigned to 37 patients followed by congenital myopathy (n = 7), cogenital muscular dystrophy (n = 5), mitochondrial myopathy (n = 4), neuropathies (n = 5) and diaphragmatic SMA (n = 1). Only 15.7% of cases remained unclassified. When EMG was correlated with final diagnosis, it was 80.6% and 75% sensitive and 68.8% and 87.5% specific for neurogenic and muscle disease, respectively. Muscle biopsy revealed neurogenic atrophy in 47.8% cases followed by normal in 37.3% and myopathic pattern in 14.97% cases. Exon7 of SMNT gene was deleted in only 50% of SMA cases.
Conclusions:
Spinal muscular atrophy was the commonest cause of floppy children. The low rate of SMNT gene deletion detected needs confirmation with further studies.