Re: Low‐molecular‐weight heparin associated with reduced fetal fraction and subsequent false‐ negative cell‐free DNA test result for trisomy 21

Dabi, Yohann; Costa, Josep; Benachi, Alexandra

doi:10.1002/uog.18984

Cited by 2 publications

(1 citation statement)

References 7 publications

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“…На уровень фетальной фракции, помимо массы тела беременной женщины, могут влиять и другие факторы. Например, есть исследования, в которых установлено, что уровень фетальной фракции ниже при применении низкомолекулярных гепаринов (хотя можно предположить, что низкий уровень фетальной фракции связан не с самими низкомолекулярными гепаринами, а с теми показаниями, в связи с кото-рыми они были назначены) [16][17][18]. Ряд исследователей отметили, что более низкое содержание фетальной фракции имеет место у женщин монголоидной расы [19].…”

Section: акушерство и перинатологияunclassified

Low Fetal Fraction of Cell-free DNA Identified by Non-invasive Prenatal DNA Testing: Possible Causes, Clinical Significance, and Tactics

Kudryavtseva¹,

Ковалев²,

Баранов³

et al. 2020

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Study Objective: To compare the rates of fetal chromosomal abnormalities (CA) detected during initial non-invasive prenatal DNA testing (NIPT) with the rates of CA found through repeat NIPT in patients with low fetal fraction or low quality of cell-free embryonic DNA. Study Design: This was a retrospective cohort study. Materials and Methods: Twenty-one thousand forty-two women who underwent NIPT in Russia between 2013 and 2018 were included in the study. The main group comprised 1,025 of the 1,044 patients with uninformative results (low fetal fraction result, making it impossible to assess the risk of CA), who consented to repeat NIPT. The control group was made up of 19,998 women who had informative results of initial NIPT. The exclusion group comprised women with low fetal fraction who declined repeat screening. The study method was targeted NIPT. Blood samples were taken from a vein and centrifuged to obtain plasma. Fetal cell-free DNA was analyzed by next-generation sequencing (NGS), a method patented by Natera for sequencing single nucleotide polymorphisms. Study Results: Initial NIPT was uninformative in 1,044 (5%) of the patients and repeat procedure yielded informative results in 821 (80.1%) out of 1,025 patients. Among the patients with informative results from the initial study, the rate of chromosomal aneuploidies was 2.4%. In the group of women with informative results from the repeat procedure, fetal CA were detected in 27 (3.3%) cases. In the subgroup of women with informative results only after a third NIPT, the prevalence of CA was 9.3% (seven out of 75 cases). The study showed that in women carrying fetuses with trisomy 18 or 13 or monosomy X, mean fetal fraction in the first trimester was significantly lower than normal. In the second trimester, significantly lower than normal fetal fraction was observed in women carrying fetuses with trisomy 18 or monosomy X. There was a statistically significant difference in fetal fraction levels between patients with body weight <50 kg and those with body weight 80-89 kg or above (р<0.05). Conclusion: The probability of detecting CA by repeat NIPT is significantly higher than in an initial procedure. If initial testing is not informative, it should be repeated. If the second procedure also fails to yield informative results, invasive prenatal diagnosis should be considered. Fetal fraction levels are lower in heavier women. Thus, other methods of prenatal diagnosis should be recommended for overweight and obese women. Keywords: non-invasive prenatal DNA testing, fetal fraction, prenatal diagnosis, Down syndrome.

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Section: акушерство и перинатологияunclassified

Low Fetal Fraction of Cell-free DNA Identified by Non-invasive Prenatal DNA Testing: Possible Causes, Clinical Significance, and Tactics

Kudryavtseva¹,

Ковалев²,

Баранов³

et al. 2020

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Fetal fraction of free-DNA: clinical-diagnostic parallels

Kudryavtseva

Ковалев

Dektyarev

2021

jour

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Introduction. Since 2011, a technology such as a non-invasive prenatal test (NIPT) has been used in the world i order o identify pregnant women at a high risk of giving birth to a child with chromosomal aneuploidy (CA). An important indicator of the test's effectiveness is the fetal fraction (FF), since its low level does not allow to give a reliable result to a patient.Aims: to determine the factors that can affect the level of FF during NIPT.Materials and methods. A retrospective comparative covenant study was carried out. The study included 288 patients who underwent NIPT in 2015-2018 after the standard complex of prenatal diagnosis (t 12-18 weeks of pregnancy). We assessed the correlation of the FF level with various clinical and anamnestic parameters and with indicators of biochemical screening for the first trimester (PAPP-A and β-ХГЧ). A comparison was made in terms of the FF level during pregnancy with a favorable and unfavorable outcome.Results. The average FF level in patient where CA was detected in the fetus was 9.01 (5.4-11)%, in the absence of CA — 9.7 (6.5-11.95)%, the difference are not statistically significant (p = 0.37). In patients with a physiological course of pregnancy, this indicator was 10.07 (6.6-12.57)%, and in patients with a complicated course of pregnancy, it was significantly lower — 8.11 (5.35-11.29)% (p = 0.02). We also analyzed the presence of a correlation between the level of FF and fetal weight at term, but no statistically significant correlation was found (r=0.13). There is a statistically significant inverse relationship between the FF level d the age of the pregnant woman, the patient's weight and body mass index, the number of pregnancies in the anamnesis, as well as a direct relationship between the FF and the β-hCG level (in MoM).Conclusions. FF is an important parameter of NIPT. A sufficient level of FF not only indicates a high reliability of the result obtained during NIPT, but also increases the chances of a favorable pregnancy outcome. The level of FF can be influenced by a number of clinical and anamnestic characteristics of the patient (weight body mass index, age, obstetric history). Studies aimed at determining the level of FF in various physiological and pathological conditions during pregnancy seem promising and thanks to them, it is possible that new models for predicting pregnancy complications will subsequently be proposed.

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Re: Low‐molecular‐weight heparin associated with reduced fetal fraction and subsequent false‐ negative cell‐free DNA test result for trisomy 21

Cited by 2 publications

References 7 publications

Low Fetal Fraction of Cell-free DNA Identified by Non-invasive Prenatal DNA Testing: Possible Causes, Clinical Significance, and Tactics

Low Fetal Fraction of Cell-free DNA Identified by Non-invasive Prenatal DNA Testing: Possible Causes, Clinical Significance, and Tactics

Fetal fraction of free-DNA: clinical-diagnostic parallels

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