can generate non-Gaussian density perturbations during the inflation (e.g., Bartolo, Matarrese, & Riotto 2002; Dvali, Gruzinov, & Zaldarriaga 2003).

Conclusions
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We have investigated the topology of CMB anisotropy from the WMAP 1-year maps by measuring the genus and its related statistics. The measured WMAP genus curves clearly deviate from the Gaussian prediction in two distinctive manners. First, the genus asymmetry parameter $\Delta g$ is positive on the Galactic southern hemisphere in the WMAP W band map ($0\fdg35$ scale), a non-Gaussian feature that is significant at $2.4\sigma$ level, while $\Delta g$ on the Galactic northern hemisphere is consistent with zero. Second, the genus amplitude difference between the north and the south hemispheres ($A_{-/+}^{\rm N} - A_{-/+}^{\rm S}$) deviates from Gaussian prediction at $2.0\sigma$ – $2.6\sigma$ levels at WMAP Q, V, and W bands. Compared to the 500 Gaussian mock observations, the observed genus amplitude differences indicate that the Gaussianity of CMB anisotropy field is ruled out at about 99% (95%) confidence level when the Kp0 mask (Kp0 mask and $b=30\degr$ Galactic cut) is applied. These non-Gaussian features have weak dependence on the Galactic cut. Similar results based on the power spectrum analysis have also been reported by Eriksen et al. 