Condition | Structural variations | Functional impact of callosal variation | |||
---|---|---|---|---|---|
Total CC | Anterior (rostrum and genu) | Midbody | Posterior (isthmus and splenium) | ||
NF1 | Enlarged area (Kayl et al. 2000; Margariti et al. 2007; Dubovsky et al. 2001); reduced FA and elevated average diffusion coefficient (Zamboni et al. 2007) | Rostral body area enlarged (Kayl et al. 2000) | Anterior and posterior midbody area enlarged (Kayl et al. 2000) | No significant findings | CC size was inversely correlated with viusual-spatial skills, motor skills, academic achievement (Moore et al. 2000); CC enlargement correlates positively with better attention (Kayl et al. 2000) |
Fragile X | No CC involvement | No CC involvement | No CC involvement | No CC involvement | Not applicable |
Turner syndrome | Case reports involving callosal dysgenesis (Kimura et al. 1990; Abd et al. 1997; Araki et al. 1987; Hori 1996) | Small genu area in children and teens (Fryer et al. 2003); enlarged genu area in adults (Cutter et al. 2006) | No sigificant findings | Small splenium area in adults (Cutter et al. 2006) | No information available |
22qDS | Enlarged area (Shashi et al. 2004; Machado et al. 2007; van Amelsvoort et al. 2001) | Longer and larger rostrum and small genu area in children (Machado et al. 2007); reduced bilateral genu volume (Sundram et al. 2010) | Reduced bilateral volume (Sundram et al. 2010) | Enlarged splenium area in adults (van Amelsvoort et al. 2001); elevated FA in splenium of both children and young adults (Barnea-Goraly et al. 2003; Machado et al. 2007); reduced splenium volume in children to early adults (Sundram et al. 2010) | On enumeration and subitizing tests, genu area correlated with faster performance and area of select regions in posterior midbody and splenium was negatively correlated with performance speed (Machado et al. 2007) |
Williams syndrome | Less concave in shape (Tomaiuolo et al. 2002; Gothelf et al. 2008; Luders et al. 2007) | No significant findings | Small area in caudal region of the callosal body (Tomaiuolo et al. 2002) | Smal area of isthmus and splenium (Luders et al. 2007; Tomaiuolo et al. 2002; Schmitt et al. 2001; Chiang et al. 2007) | Subtle loss of interhemispheric connectivity and elevated intrahemispheric connections; IHT does not improve with age (Santos et al. 2007); after age 30 years, PIQ positively correlated with genu and splenium area (Chiang et al. 2007) |
Preterm birth | Reduced area across all regions at 8 years old (Peterson et al. 2000) and in adolescence (Nosarti et al. 2004) | Low FA in genu of infants (Anjari et al. 2007) and at 8 years old (Peterson et al. 2000); enlarged genu relative to total CC area by ages 14–15 years (Nosarti et al. 2004) | Small posterior body area in infants (Counsell et al. 2008b; Peterson et al. 2000; Rademaker et al. 2004; Cooke and Abernethy 1999); low FA in CC body of infants born at <28 PCW (Anjari et al. 2007) | Small splenium area relative to total CC area in 14–15-year olds (Nosarti et al. 2004); low FA in splenium of infants with diffuse excessive high signal intensity (Counsell et al. 2006); low FA in isthmus of infants born at <28 PCW (Anjari et al. 2007) | In 2-year olds, FA of CC body and isthmus area correlated positively with developmental quotient and eye-hand coordination (Counsell et al. 2008b). In adolescents, CC area correlated positively w/VIQ, PIQ, and visuomtor integration (Peterson et al. 2000); in adolescents, bilateral-visual field matching was slowed with an atypical bilateral disadvantage—fMRI during this task revealed areas of compensatory activation in DLPFC (Santhouse et al. 2002) |
FAS | 6.8% incidence of callosal agenesis (Riley et al. 1995); reduced FA in the CC overall (Sowell et al. 2008) | Reduced FA in posterior midbody (Wozniak et al. 2009) | Reduced area (Riley et al. 1995; Sowell et al. 2001); reduced FA in the isthmus (Wozniak et al. 2009) and splenium (Sowell et al. 2008; Wozniak et al. 2009); posterior CC is displaced more anteriorly and inferiorly (Sowell et al. 2001) | White matter integrity of posterior CC is positively correlated with visual-motor integration performance in FASD groups (Sowell et al. 2008; Wozniak et al. 2009). |