Carriage of Supernumerary Sex Chromosomes Decreases the Volume and Alters the Shape of Limbic Structures

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Figure 1.
Bulk volume analysis of amygdala and hippocampus. (A) Total brain volume (tbv), amygdala, and hippocampus volume across karyotype groups, relative to typically developing males (XY). (B) Scaling of amygdala and hippocampus volume in the allometric sample (amygdala β1 = 0.89; hippocampus β1 = 0.76). (C) Comparisons of regional volume across sex and sex chromosome complement. FDR-corrected log(p) values are shown. Presence of color indicates statistical significance, and color identity/sign indicates direction of effect: for contrast A-B, blue and negative values indicate smaller volume in A versus B, red and positive value indicate larger volume in A versus B.
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Figure 2.
Surface-based analysis of amygdala and hippocampus shape. (A) Map of vertex-wise surface area scaling coefficients from log-log linear model with total bilateral region surface area. (B) Binarized surface maps showing areas of significant surface area contraction (blue) or expansion (red) for each patient contrast. (C) Spatial correlation of uncorrected t-statistic maps demonstrating convergence of SCA effects. AMY: Amygdala, HC: Hippocampus.

Table 1.

Participant characteristics

Participant characteristics
Group	XX	XY	XXX	XXY	XYY	XXYY	XXXXY	Allometric sample
n	87	79	28	56	25	19	5	79 (34 F)
Age, y
Mean (SD)	12.7 (5.1)	12.7 (4.6)	12.3 (5.7)	12.7 (4.9)	12.2 (4.9)	14.0 (5.5)	12.9 (4.8)	13.0 (0.6)
Range	5.4–25.1	5.2–25.5	5.0–24.8	5.2–26.0	5.7–23.0	5.0–23.0	7.7–17.2	12.0–14.0
FSIQ
Mean (SD)^*	113.9 (12.3)	116.6 (13.3)	94.1 (14.2)	97.6 (17.1)	91.0 (14.6)	86.9 (12.9)	55.7 (7.23)	116.3 (12.4)
SES
Mean (SD)^*	47.3 (17.1)	48.0 (21.3)	40.9 (15.9)	56.0 (20.7)	58.1 (22.4)	45.5 (22.6)	68.8 (22.4)	34.1 (19.7)

FSIQ, Full scale IQ; SES, socioeconomic status.
↵* p < 0.01 for omnibus test of significant variation across groups in core sample.

Table 2.

Descriptive statistics for bulk volume analysis

Descriptive Statistics by Karyotype Group								Omnibus test for group differences
Karyotype (n)	XX (87)	XY (79)	XXX (28)	XXY (56)	XYY (25)	XXYY (19)	XXXXY (5)	F statistic	−log(p)
Total brain volume, cm³								20.93	19.67
Mean	1261	1392	1179	1287	1418	1291	1131
SEM	9.74	13.8	22.8	17.8	24.9	29.7	36.1
Amygdala, cm³								23.78	22.15
Mean	2.32	2.54	2.05	2.26	2.43	2.19	1.86
SEM	0.02	0.03	0.04	0.03	0.06	0.05	0.06
Hippocampus, cm³								9.64	8.95
Mean	4.30	4.57	3.98	4.32	4.68	4.33	3.82
SEM	0.04	0.05	0.07	0.07	0.12	0.12	0.13