Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0026827 (hypotonia)
 5,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An A3243G point mutation of the mitochondrial tRNA(Leu(UUR)) gene was detected in a Caucasian family with maternal diabetes mellitus and signs of mitochondrial dysfunction such as muscular hypotonia, encephalopathy, lactic acidosis, stroke-like episodes (MELAS), neurosensory hearing loss, cardial pre-excitation, and short stature. Low levels (10 JDF) of islet cell antibodies (ICA) in insulin-treated diabetes of the mother and impaired glucose tolerance with high levels of ICA (80 JDF) in her older son indicated that mitochondrial diabetes mellitus may involve beta cell damage. Furthermore, exocrine pancreas cell damage may also occur since the stroke-like episodes of this son were combined with pancreatitis. In all family members HLA types and plasma antioxidants were determined. Normal concentrations of hydro- and lipophilic antioxidants (including ubiquinol-10) were found.
 ...
PMID:Islet cell antibodies in diabetes mellitus associated with a mitochondrial tRNA(Leu(UUR)) gene mutation. 881 38

Complex III (cytochrome bc1) is a protein complex of the mitochondrial inner membrane that transfers electrons from ubiquinol to cytochrome c. Its assembly requires the coordinated expression of mitochondrial-encoded cytochrome b and nuclear-encoded subunits and assembly factors. Complex III deficiency is a severe multisystem disorder caused by mutations in subunit genes or assembly factors. Sequence-profile-based orthology predicts C11orf83, hereafter named UQCC3, to be the ortholog of the fungal complex III assembly factor CBP4. We describe a homozygous c.59T>A missense mutation in UQCC3 from a consanguineous patient diagnosed with isolated complex III deficiency, displaying lactic acidosis, hypoglycemia, hypotonia and delayed development without dysmorphic features. Patient fibroblasts have reduced complex III activity and lower levels of the holocomplex and its subunits than controls. They have no detectable UQCC3 protein and have lower levels of cytochrome b protein. Furthermore, in patient cells, cytochrome b is absent from a high-molecular-weight complex III. UQCC3 is reduced in cells depleted for the complex III assembly factors UQCC1 and UQCC2. Conversely, absence of UQCC3 in patient cells does not affect UQCC1 and UQCC2. This suggests that UQCC3 functions in the complex III assembly pathway downstream of UQCC1 and UQCC2 and is consistent with what is known about the function of Cbp4 and of the fungal orthologs of UQCC1 and UQCC2, Cbp3 and Cbp6. We conclude that UQCC3 functions in complex III assembly and that the c.59T>A mutation has a causal role in complex III deficiency.
...
PMID:A mutation in the human CBP4 ortholog UQCC3 impairs complex III assembly, activity and cytochrome b stability. 2500 9