Peroxisomal proliferator activated receptor-gamma deficiency in a Canadian kindred with familial partial lipodystrophy type 3 (FPLD3).
BACKGROUND
Familial partial lipodystrophy (Dunnigan) type 3 (FPLD3, Mendelian Inheritance in Man [MIM] 604367) results from heterozygous mutations in PPARG encoding peroxisomal proliferator-activated receptor-gamma. Both dominant-negative and haploinsufficiency mechanisms have been suggested for this condition.


METHODS
We present a Canadian FPLD3 kindred with an affected mother who had loss of fat on arms and legs, but no increase in facial, neck, suprascapular or abdominal fat. She had profound insulin resistance, diabetes, severe hypertriglyceridemia and relapsing pancreatitis, while her pre-pubescent daughter had normal fat distribution but elevated plasma triglycerides and C-peptide and depressed high-density lipoprotein cholesterol.


RESULTS
The mother and daughter were each heterozygous for PPARG nonsense mutation Y355X, whose protein product in vitro was transcriptionally inactive with no dominant-negative activity against the wild-type receptor. In addition the mutant protein appeared to be markedly unstable.


CONCLUSIONS
Taken together with previous studies of human PPARG mutations, these findings suggest that PPAR-gamma deficiency due either to haploinsufficiency or to substantial activity loss due to dominant negative interference of the normal allele product's function can each contribute to the FPLD3 phenotype.
Francis
Gordon A
GA
Department of Medicine and Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada. gordon.francis@ualberta.ca
Li
Gang
G
Casey
Robin
R
Wang
Jian
J
Cao
Henian
H
Leff
Todd
T
Hegele
Robert A
RA
D002170:Canada; D003001:Cloning, Molecular; D018389:Codon, Nonsense; D004252:DNA Mutational Analysis; D003923:Diabetes Mellitus, Lipoatrophic / Q000209:etiology / Q000235:genetics*; D005192:Family Health; D005260:Female; D006579:Heterozygote; D006801:Humans; D008875:Middle Aged; D047495:PPAR gamma / Q000172:deficiency*; D010375:Pedigree; D014158:Transcription, Genetic
D018389:Codon, Nonsense; D047495:PPAR gamma