All issues > Volume 50(9); 2007

Original Article

Korean J Pediatr. 2007;50(9):868-874. Published online September 15, 2007.

Clinical characteristics of congenital myotonic dystrophy diagnosed by molecular genetic method

Sook Hyun SH Nam¹, Young Bae YB Son¹, Bo Lyun BL Lee¹, Jeehun JH Lee¹, Chang-seok CS Ki², Munhyang MH Lee¹

¹Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University school of Medicine, Seoul, Korea
¹Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University school of Medicine, Seoul, Korea
²Department of Laboratory medicine, Samsung Medical Center, Sungkyunkwan University school of Medicine, Seoul, Korea

Correspondence Munhyang MH Lee ,Email: mhlee@smc.samsung.co.kr

Abstract

Purpose
: We performed this study to investigate the perinatal and developmental features of the patients with congenital myotonic dystrophy (CDM) confirmed by the molecular genetic method and the clinical characteristics of their mother, and to identify the relation between the number of CTG repeats and the clinical severity.
Methods
: A retrospective review of the medical records and the results of the dystrophia myotonica protein kinase (DMPK) gene test was done for the patients who were confirmed as CDM through gene analysis from January 2001 to September 2006.
Results
: All of the eight patients (male 2, female 6) showed moderate to severe degree of perinatal distress and feeding difficulty associated with profound hypotonia. Three patients had the history of polyhydramnios and two patients had equinovarus deformity. The developmental milestones were delayed in all patients, which improved gradually with age. All of their mothers demonstrated myotonic symptoms and typical myopathic face. The number of CTG repeats in DMPK gene analysis ranged 1,000-2,083, and there was no significant correlation between the number of CTG repeats and the time of walking alone.
Conclusion
: All patients with CDM presented with severe hypotonia in perinatal period, and developmental delay thereafter, which were improved with age. All of their mothers manifested myotonic symptoms with typical myopathic face, and the identification of such features greatly contributed to the diagnosis of the patients. The number of CTG repeats had no significant influence on the motor development.

Keywords :Congenital myotonic dystrophy, Polyhydramnios, Equinovarus, Hypotonia, Myotonic dystrophy protein kinase, Trinucleotide repeats