Table 3.

Genetic & Telomere Results by Age Group

Discovery Cohort (n=40)
	Infants (<18 mos) (n=6)	Children (18 mos - <12 yrs) (n=29)	Adolescents & Young Adults (≥ 12 yrs) (n=5)	P-value
ATRX Mutation
Yes	0 (0% [0–40%])	5 (17% [7–36%])	5 (100% [50–100%])	<0.001
No	6 (100% [60–100%])	24 (83% [64–93%])	0 (0% [0–50%])
Telomere Length
Long	5 (83% [40–99%])	11 (38% [21–58%])	4 (80% [34–99%])	0.051
Short	1 (17% [1–60%])	18 (62% [42–79%])	1 (20% [1–66%])
Validation Cohort (n=64)
	Infants (<18 mos) (n=12)	Children (18 mos - <12 yrs) (n=25)	Adolescents & Young Adults (≥12 yrs) (n=27)	P-value
ATRX Mutation
Yes	0 (0% [0–24%])	4 (16% [6–35%])	9 (33% [17–54%])	0.048
No	12 (100% [76–100%])	21 (84% [65–94%])	18 (67% [46–83%])
All Patients Combined (n=104)
	Infants (<18 mos) (n=18)	Children (18 mos - <12 yrs) (n=54)	Adolescents & Young Adults (≥ 12 yrs) (n=32)	P-value
ATRX Mutation
Yes	0 (0% [0–17%])	9 (17% [9–29%])	14 (44% [28–62%])	<0.001
No	18 (100% [83–100%])	45 (83% [71–91%])	18 (56% [38–72%])

^{^}Telomere length data were available only for the discovery cohort

Proportions are presented with 95% confidence intervals in brackets