Muscle pathology shows LAMP2 nonsense, splice, or exon 9b mutations lead to either trace protein or no significant level drop.[15] Additionally, in female patients with DD, the detection of LAMP2 protein reveals a mosaic distribution of LAMP2 positive and negative muscle fibers.[16] Mosaic LAMP2 expression in female DD patients explains their milder, later-onset phenotypes and is diagnostically critical: it distinguishes asymptomatic carriers from noncarriers and avoids misdiagnosis with myopathies showing uniform LAMP2 expression, aiding early surveillance. The gene discussed is LAMP2; the disease is dentin dysplasia.