Unusual precocious diagnosis of Duchenne muscular dystrophy by SNP-array in a 6-month old baby

Abstract

Microdeletions and microduplications are involved in many cases of malformations, developmental delay (DD), autism (A) and growth disturbances (GD). Molecular karyotyping (MC) performed by microarray technology is a valuable method frequently used to elucidate the etiology of these clinical expressions, essentially contributing to the diagnosis of rare genetic diseases produced by DNA copy number variations (CNVs). MC has offered a higher diagnostic yield for genetic testing of patients with unexplained DD, A and GD than a G-banded karyotype, primarily because of its higher sensitivity in detecting submicroscopic deletions and duplications. In addition, the molecular karyotype approach using the SNP-array method also allows highlighting the regions of loss of heterozygosity and uniparental disomy, which are the basis of some genetic syndromes. In this paper we will present a rare case of a 6 months old boy, referred for MC due to global developmental delay, axial hypotonia, with limbs hypertonia, heart malformation (atrial septal defect). SNP-Array analysis identified a 606,3 Kb microdeletion in the Xp21.1 region, that contains 39 exons of dystrophin gene. This finding was confirmed also with additional MLPA testing. In conclusion, it is an unusual, precocious diagnosis of Duchenne muscular dystrophy, during first year of life, referred for atypical presentation, main clinical feature being global developmental delay.