Early noninvasive prenatal detection of a fetal CRB1 mutation causing Leber congenital amaurosis.
OBJECTIVE
Leber congenital amaurosis (LCA) is one of the most severe inherited retinal dystrophies with the earliest age of onset. Mutations in the Crumbs homologue 1 (CRB1; OMIM 600105) gene explain 10%-24% of cases with LCA depending on the population. The aim of the present work was to study a fetal mutation associated to LCA in maternal plasma by a new methodology in the noninvasive prenatal diagnosis field: the denaturing High Performance Liquid Chromatography (dHPLC).


METHODS
This study presents the case of a compound heterozygous fetus for two mutations in CRB1 (1q3.1-q32.2). dHPLC and automated DNA sequencing were used to detect the paternally inherited fetal mutation in a maternal plasma sample collected at the 12th week of gestation. To test the detection limit of dHPLC, we made serial dilutions of paternal DNA in control DNA.


RESULTS
We were able to detect the presence of the paternally inherited fetal CRB1 mutation in maternal plasma by dHPLC. Moreover, by comparing chromatograms of serial dilutions to the plasma sample, we could ascertain that the percentage of fetal DNA in maternal plasma was at least 2%. However, the detection of the fetal mutation was not possible by automated DNA sequencing.


CONCLUSIONS
dHPLC seems to be sensitive enough to detect small amounts of fetal DNA in maternal plasma samples. It could be a useful tool for the noninvasive prenatal detection of paternally inherited point mutations associated with retinopathies.
Bustamante-Aragones
Ana
A
Department of Genetics, Fundacion Jimenez Diaz-Capio, CIBERER, Madrid, Spain. abustamante@fjd.es
Vallespin
Elena
E
Rodriguez de Alba
Marta
M
Trujillo-Tiebas
Maria Jose
MJ
Gonzalez-Gonzalez
Cristina
C
Diego-Alvarez
Dan
D
Riveiro-Alvarez
Rosa
R
Lorda-Sanchez
Isabel
I
Ayuso
Carmen
C
Ramos
Carmen
C
D001766:Blindness / Q000151:congenital* / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid; D004252:DNA Mutational Analysis; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D005333:Fetus / Q000378:metabolism; D005789:Genealogy and Heraldry; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009691:Nucleic Acid Denaturation; D015418:Optic Atrophies, Hereditary / Q000175:diagnosis* / Q000235:genetics*; D010375:Pedigree; D011247:Pregnancy; D011296:Prenatal Diagnosis
C448939:CRB1 protein, human; D005136:Eye Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins