Related Experiment Videos

Determining Ethnic Disparities Inherent to Tier 3 Vs. Tier 4 Carrier Screening

Vaishali Mehta1, Emily B Rosenfeld2, Julia Geltch3

  • 1Department of Obstetrics, Gynecology, and Reproductive Sciences, Rutgers Robert Wood Johnson Medical School, Rutgers Robert Wood Johnson, New Brunswick, New Jersey, USA.

Prenatal Diagnosis
|June 22, 2026
PubMed

Insights

Tier 4 carrier screening panels identify more carriers across diverse ethnic groups than traditional Tier 3 panels. Universal Tier 4 screening is recommended for better carrier ascertainment and lower number needed to screen (NNS) in all populations.

Area of Science:

  • Genetics
  • Population Health
  • Medical Diagnostics

Background:

  • Carrier screening panels traditionally use frequency thresholds based on European populations.
  • This approach may lead to ethnic disparities in carrier status ascertainment.
  • Underrepresented ethnic groups may be missed by current screening methods.

Purpose of the Study:

  • Evaluate ethnic disparities in carrier status ascertainment between Tier 3 and Tier 4 screening panels.
  • Assess the utility of Tier 4-only screening in ethnically diverse cohorts.
  • Determine the prevalence and number needed to screen (NNS) for Tier 4 variants across different regions.

Main Methods:

  • Retrospective chart review of 2000 adults undergoing carrier screening.
  • Ethnicity mapping to UN Geoscheme regions for analysis.
  • Calculation of prevalence and NNS for Tier 4-only variants by geographic region and ancestral subgroup.

Main Results:

  • 65.7% of patients carried at least one Tier 4-only variant, with high prevalence across most ancestral subgroups.
  • NNS for Tier 4-only carriers ranged from 1.0 to 2.2, most efficient in Africa, Southeast Asia, and Eastern Europe.
  • Carrier couples were identified with NNS from 7.3 to 58.1 across regions.

Conclusions:

  • Tier 3 panels inadequately identify carriers in underrepresented ethnic groups.
  • Tier 4 panels offer superior carrier ascertainment in diverse populations with lower NNS.
  • Universal Tier 4 carrier screening is supported by these findings.
Abstract

Related Concept Videos

Test for Homogeneity01:23

Test for Homogeneity

The goodness–of–fit test can be used to decide whether a population fits a given distribution, but it will not suffice to decide whether two populations follow the same unknown distribution. A different test, called the test for homogeneity, can be used to conclude whether two populations have the same distribution. To calculate the test statistic for a test for homogeneity, follow the same procedure as with the test of independence. The hypotheses for the test for homogeneity can be stated as...
Stereotypes, Prejudice, and Discrimination02:55

Stereotypes, Prejudice, and Discrimination

Humans are very diverse and although we share many similarities, we also have many differences. The social groups we belong to help form our identities (Tajfel, 1974). These differences may be difficult for some people to reconcile, which may lead to prejudice toward people who are different. Prejudice is a negative attitude and feeling toward an individual based solely on one’s membership in a particular social group (Allport, 1954; Brown, 2010). Prejudice is common against people who are...