Glycerol metabolism and the determination of triglycerides--clinical, biochemical and molecular findings in six subjects.
Recent recommendations in the National Cholesterol Education Program Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults (ATPIII) are expected to increase the number of triglyceride (TG) determinations and consequently the risk of misinterpretation of "non-blanked" results with co-determination of free glycerol. Glycerol-kinase deficiency (GKD) is one cause of falsely elevated TG results. The natural history of isolated GKD with symptom-free cases and cases with e.g. severe episodes of hypoglycemia and/or ketoacidosis challenges the laboratories to identify cases of GKD and family members at risk. "Blanked" methods reporting both glycerol and TG concentration are therefore desirable. Molecular studies of the glycerol kinase (GK) and DAX1 genes were performed on four cases of "persistent hypertriglyceridemia" found in an Italian population and on two pediatric cases with high serum glycerol concentration. Two new missense mutations were found (C358Y, T961). Molecular modeling on GK from E. coli, indicate that these mutations are located in parts of the enzyme important for enzyme formation or activity. One splice-site mutation, (IVS9A-1G>A), was found in two brothers. Splice-junction analysis indicates that it destroys the splice site and results in a mixture of mRNA. Deletion of the GK and DAX1 genes was found in one child with symptoms of adrenal failure. A female with glycerolemia and glyceroluria had normal GK activity but possibly slightly decreased ability to oxidize glycerol.
Hellerud
Christina
C
Department of Clinical Chemistry, Sahlgrenska University Hospital, Göteborg University, Gothenburg, Sweden. Christina.Hellerud@clinchem.gu.se
Burlina
Alberto
A
Gabelli
Carlo
C
Ellis
James R
JR
Nyholm
Per-Georg
PG
Lindstedt
Sven
S
D000307:Adrenal Gland Diseases / Q000235:genetics; D000483:Alleles; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D002648:Child; D002675:Child, Preschool; D057137:DAX-1 Orphan Nuclear Receptor; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D018740:Genetic Heterogeneity; D005990:Glycerol / Q000378:metabolism*; D005991:Glycerol Kinase / Q000172:deficiency / Q000235:genetics*; D006801:Humans; D015228:Hypertriglyceridemia / Q000201:enzymology / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000235:genetics*; D012097:Repressor Proteins; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics*; D014280:Triglycerides / Q000378:metabolism*
D057137:DAX-1 Orphan Nuclear Receptor; D017931:DNA Primers; D004268:DNA-Binding Proteins; C539965:NR0B1 protein, human; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins; D014157:Transcription Factors; D014280:Triglycerides; D005991:Glycerol Kinase; D005990:Glycerol