Proteomic analysis is widely used for the detection of diagnostic
markers. in the present study amniotic fluid supernatants (AFS) from
pregnancies with Down syndrome (DS) fetuses and from chromosomally
normal fetuses in the 17th week of gestation were analyzed by 2-DE. Gel
comparison revealed significant differences in the two groups. Spots
with different expression levels were excised and proteins were
identified by MALDI-MS and nano-ESI-MS/MS. Splicing factor
arginine/serine-rich 4 (SFRS4; Q08170) was present only in AFS from DS
fetuses and completely absent in the control group. Quantitative
differences were detected for alpha-1-microglobulin (AMBP; P02760),
collagen alpha 1 (1) chain (CO1A1; P02452), collagen alpha 1 (III) chain
(CO3A1; P02461), collagen alpha 1 (V) chain d (CO5A1; P20908), and
basement membrane-specific heparin sulfate proteoglycan core protein
(PGBM; P98160). These proteins were increased in cases with DS, whereas
protein IBP-1 (P08833) was decreased by 40% compared with chromosomally
normal fetuses. Four proteins, CO1A1, CO3A1, CO5A1, and PGBM, appeared
as fragments. As differentially expressed proteins were present in all
pregnancies with DS tested, they may represent useful potential markers
for prenatal diagnosis. However, for protein biomarkers to be of any
clinical utility, systematic analysis of the maternal serum should be
conducted