Table 4.

Prenatal guidelines for the 22q11.2 microdeletion.

Genetic diagnosis of 22q11.2 microdeletion in conceptus/embryo/fetus

Prenatal testing using chromosomal microarray or MLPA to analyze chorionic villus sample (10–13 weeks gestational age) or chromosome preparations from fetal cells obtained by amniocentesis (beginning at 15 weeks gestational age). FISH is an option when there is a known familial 22q11.2 deletion involving the typical deletion region. Preimplantation genetic testing (PGT-SR) of a fertilized embryo, by IVF, is available in many locations.

Genetic screening of 22q11.2 microdeletion in embryo/fetus

Noninvasive prenatal genetic screen (NIPS) NIPS can be offered from 9 weeks gestational age; sensitivity and specificity of the method used need to be discussed. Ultrasound examination for potential fetal anomalies First trimester for increased nuchal translucency, severe structural anomalies. Second-trimester high-resolution ultrasound examination, including screening for cardiac, renal, skeletal, and other anomalies (best from 18 weeks gestation); assess thymus when possible. Fetal echocardiogram (18–22 weeks gestational age). Third trimester for polyhydramnios, intrauterine growth restriction (IUGR), further assessment for anomalies.

When fetus has tested positive for a 22q11.2 microdeletion

Genetic counseling regarding prognosis, including that prenatal ultrasound examination does not rule out all anomalies and does not predict postnatal course or lifetime features of 22q11.2DS. Clinical genetic diagnostic testing of both parents to determine whether one has the 22q11.2 deletion, expected in 10–15% of cases. Consider delivery at a tertiary care center with knowledge and resources to care for neonates with 22q11.2DS.

When a parent has a 22q11.2 microdeletion

Provide genetic counseling, ideally preconception, including options as above.