Yonsei Med J.  2017 Sep;58(5):1051-1054. 10.3349/ymj.2017.58.5.1051.

Clinical Characteristics of Spinal Muscular Atrophy in Korea Confirmed by Genetic Analysis

• Hwang H
• Lee JH
• Choi YC

• KMID: 2418945
• DOI: http://doi.org/10.3349/ymj.2017.58.5.1051

Abstract

The objective of this study was to review the clinical characteristics of patients with spinal muscular atrophy and to emphasize the importance of performing genetic mutational analysis at initial patient assessment. This is a single center oriented, retrospective, and descriptive study conducted in Seoul, South Korea. Genetic mutational analysis to detect the deletion of exon 7 of the SMN1 gene on chromosome 5q13 was performed by multiplex ligation-dependent probe amplification. Clinical features, electrodiagnostic study results, muscle biopsy results, and laboratory test results were reviewed from patient medical records. Of all 28 patients (15 males and 13 females), all showed bilateral symmetric proximal dominant weakness. Among them, 3 patients were classified as type I, 14 patients as type II, and 11 patients as type III. Twenty-five patients had scoliosis and eight of these patients received surgical treatment for scoliosis with improvement in clinical outcomes. Ventilator support was used in 15 patients. In terms of the diagnostic process, 15 patients had completed an electrodiagnostic study and muscle biopsy before genetic testing, and six of these patients were initially misdiagnosed with myopathy. Owing to the similar clinical features of SMA and congenital myopathy, an electrodiagnostic study and muscle biopsy could create confusion in the correct diagnosis in some cases. Therefore, it is recommended that genetic mutation analysis should be conducted along with an electrodiagnostic study or muscle biopsy in the diagnostic process for spinal muscular atrophy.

Keyword

Spinal muscular atrophy; Survival Motor Neuron 1; SMN 1; scoliosis

MeSH Terms

Adolescent
Biopsy
Child
Child, Preschool
Electrodiagnosis
Female
*Genetic Testing
Humans
Infant
Infant, Newborn
Male
Muscle, Skeletal/pathology
Muscular Atrophy, Spinal/*genetics/*pathology
Reproducibility of Results
Republic of Korea
Retrospective Studies

Reference

1. Faravelli I, Nizzardo M, Comi GP, Corti S. Spinal muscular atrophy--recent therapeutic advances for an old challenge. Nat Rev Neurol. 2015; 11:351–359.

2. Mercuri E, Bertini E, Iannaccone ST. Childhood spinal muscular atrophy: controversies and challenges. Lancet Neurol. 2012; 11:443–452.

3. Arkblad EL, Darin N, Berg K, Kimber E, Brandberg G, Lindberg C, et al. Multiplex ligation-dependent probe amplification improves diagnostics in spinal muscular atrophy. Neuromuscul Disord. 2006; 16:830–838.

4. Gregoretti C, Ottonello G, Chiarini Testa MB, Mastella C, Ravà L, Bignamini E, et al. Survival of patients with spinal muscular atrophy type 1. Pediatrics. 2013; 131:e1509–e1514.

5. Granata C, Merlini L, Magni E, Marini ML, Stagni SB. Spinal muscular atrophy: natural history and orthopaedic treatment of scoliosis. Spine (Phila Pa 1976). 1989; 14:760–762.

6. Robinson D, Galasko CS, Delaney C, Williamson JB, Barrie JL. Scoliosis and lung function in spinal muscular atrophy. Eur Spine J. 1995; 4:268–273.

7. Chou SH, Lin GT, Shen PC, Lue YJ, Lu CC, Tien YC, et al. The effect of scoliosis surgery on pulmonary function in spinal muscular atrophy type II patients. Eur Spine J. 2017; 26:1721–1731.

8. Wang CH, Finkel RS, Bertini ES, Schroth M, Simonds A, Wong B, et al. Consensus statement for standard of care in spinal muscular atrophy. J Child Neurol. 2007; 22:1027–1049.

9. Vilchis Z, Najera N, Pérez-Duran J, Najera Z, Gonzalez L, del Refugio Rivera M, et al. The high frequency of genetic diseases in hypotonic infants referred by neuropediatrics. Am J Med Genet A. 2014; 164A:1702–1705.

10. Zarkov M, Stojadinović A, Sekulić S, Barjaktarović I, Perić S, Keković G, et al. Association between the SMN2 gene copy number and clinical characteristics of patients with spinal muscular atrophy with homozygous deletion of exon 7 of the SMN1 gene. Vojnosanit Pregl. 2015; 72:859–863.

11. Zheleznyakova GY, Kiselev AV, Vakharlovsky VG, Rask-Andersen M, Chavan R, Egorova AA, et al. Genetic and expression studies of SMN2 gene in Russian patients with spinal muscular atrophy type II and III. BMC Med Genet. 2011; 12:96.

12. Prior TW. Spinal muscular atrophy diagnostics. J Child Neurol. 2007; 22:952–956.