Landmark study establishes live-birth prevalence of 22q

by 22q Administrator

Individuals with 22q often face many long-term physical and mental health problems. Getting the correct diagnosis early in life allows doctors to anticipate and deal with health issues, which helps avoid complications. Therefore, experts in 22q have long advocated for newborn screening for this syndrome. However, to convince policy makers to add 22q to newborn screening programs, we must show that 22q is in fact common enough to be worth the effort.

A new study aimed to determine the live birth prevalence of 22q, that is: how often does 22q happen in newborn babies? Our team, led by medical student Christina Blagojevic, searched for 22q deletions in 30,074 babies born in Ontario between January 2017 and September 2018. We found 14 newborns with confirmed 22q deletions in the sample, which meant that for every 2148 babies born alive, 1 had 22q (prevalence = 1 in 2148 live births). We also found that babies with 22q likely had younger mothers, were smaller compared to babies born after the same length of pregnancy, and had lower counts of a particular blood test, which could signal future problems with the immune system.

Now that we know the prevalence of 22q is 1 in 2148, let’s compare this number with the prevalence of other genetic syndromes. The prevalence of cystic fibrosis (CF) 1 in 3600, while that of severe combined immunodeficiency (SCID) is 1 in 50 000 to 1 in 100 000. Both CF and SCID are less prevalent than 22q, but both are genetic conditions that are screened for in Ontario’s current Newborn Screening program. Unfortunately, 22q is not known to be in standard newborn screening programs of any countries.

This study confirms that 22q is a relatively common “rare” condition. From a public health stand point, the results support the importance of screening for 22q either prenatally or in the first days of life through newborn screening. An early system of diagnosis would allow individuals with 22q to receive timely management of their health problems, which will decrease adverse outcomes.

Estimate of the contemporary live-birth prevalence of recurrent 22q11.2 deletions: a cross-sectional analysis from population-based newborn screening [Full text]
Blagojevic C, Heung T, Theriault M, Van L, Tomita-Mitchell A, Chakraborty P, Kernohan K, Bulman DE, Bassett AS
CMAJ Open, 2021, 9 (3) E802-E809
doi: 10.9778/cmajo.20200294