What does fetal fraction mean on Panorama test?

Fetal fraction describes the proportion of the total cfDNA that is fetal in origin. The ‘fetal’ component is actually derived from placental trophoblast (2, 3). Thus, cfDNA analysis (NIPT) for fetal trisomy can be considered a ‘liquid biopsy’ of the placenta.

What is a normal fetal fraction?

The proportion derived from the placenta is known as the fetal fraction. When measured between 10 and 20 gestational weeks, the average fetal fraction in the maternal plasma is 10% to 15% but can range from under 3% to over 30%.

What fetal fraction is needed for Panorama?

Through the use of this science, Panorama is accurate at fetal fractions as low as 4%3, and can be used earlier in the pregnancy than other NIPTs. The NATUS algorithm incorporates over 3,000 SNPs per chromosome evaluated, allowing Panorama to select SNPs that are not impacted by ethnicity.

What does fetal fraction mean on NIPT test?

The fetal fraction (FF), i.e. the amount of fetal cfDNA detected in the plasma sample analysed compared to the total cfDNA, is an important parameter to determine for the performing of NIPT tests, since with very low FF quantities the aneuploidies may not be detectable, and therefore produce false negatives results.

What is considered high fetal fraction?

High FF was defined as the 95th percentile or higher, and normal FF as being between the fifth and 95th percentiles. The 102 women with low FF, less than the fifth percentile, were excluded from further analysis because such women are known to be at increased risk of aneuploidy and adverse pregnancy outcomes.

Why is my fetal fraction high?

Elevated levels of fetal cell free DNA (cfDNA) in maternal circulation have been observed in pathologic conditions such as preeclampsia and preterm birth at the time of diagnosis. Evidence is conflicting, however, on the clinical significance of a high fetal fraction (FF) result on routine aneuploidy screening.

What is a good fetal fraction percentage?

The proportion of cfDNA in maternal blood that comes from the placenta is known as the fetal fraction. Generally, the fetal fraction must be above 4 percent, which typically occurs around the tenth week of pregnancy. Low fetal fractions can lead to an inability to perform the test or a false negative result.

Why is my fetal fraction low?

Reasons for low fetal fractions include testing too early in the pregnancy, sampling errors, maternal obesity, and fetal abnormality. There are multiple NIPT methods to analyze fetal cfDNA. To determine chromosomal aneuploidy, the most common method is to count all cfDNA fragments (both fetal and maternal).

Is low fetal fraction bad?

Conclusions. Low fetal fraction on cfDNA testing may be a marker of poor placental development and placental dysfunction, as there is a significant correlation with first-trimester markers for PE and risks for PE and FGR.

Can fetal fraction be too high?

Is a high fetal fraction good?

There was no significant association between high FF and either preterm birth or hypertensive disorders of pregnancy. Conclusion: Women with a high FF in the first trimester are at increased risk of delivering a small for gestational age infant

How quickly does fetal fraction increase?

The average increase in fetal fraction per week in the normal BMI group was 0.36 units; in women with BMIs of 35 or greater, the average increase was 0.10 units/wk.

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