Neonatal abstinence syndrome is a potential cause of low TREC copy number

Table 1 Clinical and immunological characteristics of 3 newborns presenting with abnormal TREC copy number

	GA (weeks)	Sex	Mode of delivery	Birth weight (g)	Antenatal exposures	Medical history	TREC (number/µL)		T cell counts^a (× 10⁹/L)
	GA (weeks)	Sex	Mode of delivery	Birth weight (g)	Antenatal exposures	Medical history	Initial	Repeat	T cell counts^a (× 10⁹/L)
1	36	M	CS	2961	Methadone Marijuana	Neonatal abstinence syndrome	66	385	CD3 + 3.22 CD3 + CD4 + 2.53 CD3 + CD8 + 0.78
2	37	F	CS	1590	Methadone Heroin	Neonatal abstinence syndrome Symmetrical IUGR	46	299	CD3 + 6.64 CD3 + CD4 + 3.85 CD3 + CD8 + 2.79
3	36 + 6	F	CS	2000	Methadone Heroin	Neonatal abstinence syndrome Symmetrical IUGR	51	253	CD3 + 7.74 CD3 + CD4 + 5.93 CD3 + CD8 + 1.69

Patients 2 and 3 were diachorionic diamnionic twins. All 3 newborns had their second TREC copy number and T cell counts measured on the 13th day of life
CS caesarean section, GA gestational age at birth, IUGR intrauterine growth restriction, SVD spontaneous vaginal delivery, TREC T cell receptor excision circle
^aNormal values for T cell counts: CD3 + 1.5–5.0 × 10⁹/L, CD3 + CD4 + 0.90–3.60 × 10⁹/L, CD3 + CD8 + 0.30–1.40 × 10⁹/L

ISSN: 1710-1492