ClinVar

Seneca et al. (1996) described a female newborn who presented with seizures and episodic lactic acidemia, symptoms consistent with mitochondrial dysfunction. They found a 2-bp deletion at positions 9204/5 or 9205/6 at the junction between the 2 genes MTATP6 and MTCO3 (516050) that removed the termination codon for RNA14, the ATPase 8- and 6-encoding bicistronic mRNA unit. The deletion removed the termination codon for MTATP6 and set MTCO3 immediately in-frame, generating a predicted ATPase6/COX3 fusion protein. Temperley et al. (2003) showed that accurate processing at this site still occurred, but there was a markedly decreased steady-state level of RNA14. The majority of mutated RNA14 terminated with short poly(A) extensions, and a second, partially truncated population was also present. Initial maturation of mutated RNA14 was unaffected, but deadenylation occurred rapidly. Inhibition of mitochondrial protein synthesis showed that the deadenylation was dependent on translation; deadenylation also enhanced mRNA decay. Temperley et al. (2003) referred to the deletion as mu-delta-9205.