1
Referee #2
Reviewer's report
Title:The utility of circulating LHCGR as a predictor of Down's syndrome in early
pregnancy
Version:1Date:22 March 2014
Reviewer:Liliam Cristine Rolo Paiato
Reviewer's report:
Major Compulsory Revisions
Level of interest:An article of importance in its field
Quality of written English:Acceptable
Statistical review:No, the manuscript does not need to be seen by a statistician.
Declaration of competing interests:
I declare that I have no competing interests.
Good manuscript, but some corrections are necessary.
ABSTRACT:
Good abstract.
Key words: add screening test, noninvasive prenatal test (NIPT)
Answer: Added in the revised manuscript
TEXT:
INTRODUCTION:
In the first paragraph, line 9, it is better to mention “biophysical and biochemical
parameters” than biochemical and biometric (most used terms).
Answer: Replaced ‘biochemical and biometric’ with ‘ biophysical and biochemical
Parameters’
METHODS:
Did women involved agree to participate this study?
In the methods information about the written informed consent and the approval
of the Ethics in Research are necessary.
There is no description of the control group as well as the number of patients
included in this group.
This study approach was approved by the Scientific Ethical Committee of the Hospital
Clinic Barcelona, Universitat de Barcelona. All participating women in this manuscript
have given written informed consent during the first-trimester Down syndrome
screening.
RESULTS
In the abstract, there are reports of 300 control patients, but in the blox plot graph
2
(Figure 1) the number reported is 206. This information is confused, it is necessary to
improve the results.
Answer: Please note that there are two ELISA assay systems: the total soluble LHCGR
(sLHCGR) and hCG-LHCGR complex. There were 300 control and 40 Down’s samples
in this study. In order to directly compare with the results of our published data
(reference 8), the hCG-LHCGR (hormone-receptor complex) analysis was carried out in
all samples to establish the diagnostic value of the assay as described in Table 1
(revised). However, sLHCGR analysis was carried out on 206 control (out of 300) and all
(40) Down’s samples described in Figure 1. Therefore, control N value in Figure 1 was
206 and not 300 as shown in Table 1.
DISCUSSION:
it failed to emphasize the importance of biochemical screening in association with the
clinical and biophysical characteristics.
Currently, the routine non-invasive prenatal testing (NIPT) involves the biochemical screening of
maternal serum biomarkers (PAPP-A and free hCGbeta) at 9-14 wks of gestation as well the
measurement of fetal nuchal translucency (NT) by ultrasonography. The algorithms based on
these results, and other parameters including maternal age, BMI, parity (twin or singleton) etc,
are used to assess the risk for fetal aneuploidy. The biochemical and NT testing together could
detect 79-90% of trisomy 21 at a FPR of 5%[1, 2]. The screen-positive pregnancies, following
initial risk assessment, are referred to more invasive genetic and molecular testing by
CVS/amniocentesis for definitive diagnosis of aneuploidy or other chromosomal abnormalities.
Moreover, it must be emphasized that cfDNA should not be used as a general screening
population based on specific criteria (references about must be used).
Answer:
Current guidelines on NIPT proposed by the International Society for Prenatal Diagnosis and
others [11, 12 13] support the idea of cfDNA testing on ‘high-risk’ pregnancies only. The highrisk was defined on the basis of maternal age (≥ 35 yrs), screen-positives by biochemical and
ultrasound testing, history of aneuploidy and parental balanced Robertsonian translocation
associated with trisomy 13 and 21 [11]. In the absence of sufficient validation of the cfDNA
testing for fetal aneuploidy, it should be considered as ‘advanced screening test’ and is not fully
diagnostic. Additionally, the current cfDNA testing for aneuploidy is insufficient to account for
half the chromosomal abnormalities detected by molecular analysis of samples derived from
CVS or amniocentesis [14]
Thus, the importance to use new markers in serum screening could be improved.
Therefore, the discussion should be improved.
Answer:
An important objective of this study was to examine whether serum LHCGR could
increase the screening efficiency of PAPP-A plus free-hCGbeta which are currently
used as first trimester biochemical markers together with NT for prenatal risk
assessment of fetal anuploidy. In order to compare the relative screening efficiencies in
this study, first the DR and FPR at fixed cut-off values for PAPP-A (≤0.5 MoM), βhCG (≥
1.7 MoM), hCG-sLHCGR (≤ 2.0 & ≥ 20.0 MoM) were calculated. Out of all combinations,
the DR for Down’s syndrome with PAPP-A plus hCG-sLHCGR was highest (57.5%) with
FPR of 2.3%. These results were comparable (DR, 58.1% and FPR, 4.5%) to our
published data on 43 Down’s samples from two sources [8]. The additive effect of hCGsLHCGR on PAPP-A and βhCG measurement was 35% (compared to 21% in published
3
data, [8]. The additive effect is defined as T21 pregnancies identified by the PAPP-A +
hCG-sLHCGR which could not be detected by conventional PAPP-A and βhCG
measurements. Finally, hCG-sLHCGR, in combination with PAPP-A, βhCG and NT
(≥.2.0 MoM), detected 95% (38/40) DS pregnancies.