MTM1 and centronuclear myopathy: In A0831013, presenting with neonatal hypotonia, a new 403-bp hemizygous, maternally inherited deletion spanning parts of the gene promoter and 5′ UTR of MTM1 was identified, including the transcription start site (TSS) (NM_000252.2(MTM1): c.-76_-11del), consistent with a diagnosis of myotubular myopathy.