Newborn screening and genomic analysis of duchenne muscular dystrophy in Henan, China

Abstract

Background: Duchenne Muscular Dystrophy (DMD) is a rare disorder caused by mutations in the dystrophin gene. Recent availability in treatment for DMD raised the need of early screening in our center, but newborn screening (NBS) for DMD has not been carried out in Henan Province.

Objectives: To determine an optimal cutoff value through the quantitative determination of the creatine kinase isoform MM (CK-MM) concentration dried blood spot (DBS) to identify male DMD, and to evaluate assess the detection rate and mutation spectrum of DMD in Henan, China.

Methods: The CK-MM level in DBS was measured using with a GSP® neonatal creatine kinase -MM kit from 13,110 male newborns to establish the cut-off value for CK-MM. Multiplex ligation-dependent probe amplification (MLPA) were carried out for infants with elevated CK levels to detect DMD gene deletions/ duplications, NGS and sanger sequencing were then applied to exclude MLPA-negative samples to single-nucleotide variants. Phenotype-genotype correlations were analyzed using REVEL For novel missense mutations.

Results: Statistical analysis of CK-MM value of the 13,110 neonates suggested that the cut-off value may be set as 472 ng/mL. 3 cases of DMD were screened among 13,110 newborns, all of whom had CK-MM levels >600 ng/mL. We detected 4 rare variants in DMD gene, including 2 exon deletions (deletion of exon 52 and deletion from exon 3 to exon 7) and 2 point variants (c.9568C>T and c.4030C>T). Two cases were all exon deletions, one case was compound heterozygous variants.

Conclusions: The estimated incidence of male neonatal DMD was 1:4,370 in Henan province. NBS is of great value to the early intervention and treatment of the disease, and is fundamental to support public health decision-making. The experience from this study provided a model that will allow further expansion and facilitate establishment a universal public health screening in Henan hospital systems.

Keywords: Creatine kinase MM; Cut-off value; Duchenne muscular dystrophy; Newborn screening; Variants.