LAMA2 and muscular dystrophy, limb-girdle, autosomal recessive 23: MDC1A exhibits high clinical heterogeneity in severity which presents as neonatal-onset merosin-deficient muscular dystrophy (the classic MDC1A phenotype) or a milder form, such as childhood- or adult-onset autosomal recessive limb-girdle muscular dystrophy 23 (LGMDR23) (5).