GRACILE syndrome, a lethal metabolic disorder with iron overload, is caused by a point mutation in BCS1L.
GRACILE (growth retardation, aminoaciduria, cholestasis, iron overload, lactacidosis, and early death) syndrome is a recessively inherited lethal disease characterized by fetal growth retardation, lactic acidosis, aminoaciduria, cholestasis, and abnormalities in iron metabolism. We previously localized the causative gene to a 1.5-cM region on chromosome 2q33-37. In the present study, we report the molecular defect causing this metabolic disorder, by identifying a homozygous missense mutation that results in an S78G amino acid change in the BCS1L gene in Finnish patients with GRACILE syndrome, as well as five different mutations in three British infants. BCS1L, a mitochondrial inner-membrane protein, is a chaperone necessary for the assembly of mitochondrial respiratory chain complex III. Pulse-chase experiments performed in COS-1 cells indicated that the S78G amino acid change results in instability of the polypeptide, and yeast complementation studies revealed a functional defect in the mutated BCS1L protein. Four different mutations in the BCS1L gene have been reported elsewhere, in Turkish patients with a distinctly different phenotype. Interestingly, the British and Turkish patients had complex III deficiency, whereas in the Finnish patients with GRACILE syndrome complex III activity was within the normal range, implying that BCS1L has another cellular function that is uncharacterized but essential and is putatively involved in iron metabolism.
Visapää
Ilona
I
Department of Human Genetics, University of California Los Angeles School of Medicine, USA.
Fellman
Vineta
V
Vesa
Jouni
J
Dasvarma
Ayan
A
Hutton
Jenna L
JL
Kumar
Vijay
V
Payne
Gregory S
GS
Makarow
Marja
M
Van Coster
Rudy
R
Taylor
Robert W
RW
Turnbull
Douglass M
DM
Suomalainen
Anu
A
Peltonen
Leena
L
D000074183:ATPases Associated with Diverse Cellular Activities; D000818:Animals; D015152:Blotting, Northern; D019556:COS Cells; D014450:Electron Transport Complex III / Q000378:metabolism; D005260:Female; D005816:Genetic Complementation Test; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D019190:Iron Overload / Q000201:enzymology / Q000235:genetics*; D008297:Male; D008659:Metabolic Diseases / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D017354:Point Mutation; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017422:Sequence Analysis, DNA; D014162:Transfection
C435491:BCS1L protein, human; D011506:Proteins; D000074183:ATPases Associated with Diverse Cellular Activities; D014450:Electron Transport Complex III