HTRA1 and snowflake vitreoretinal degeneration: Conversely, in a Japanese study in patients with adult-onset SVD [118], more than 90% of monogenic cerebral SVD (mgCSVDs) were diagnosed by screening for NOTCH3, HTRA1, and ABCC6, concluding that the target sequences for these three genes could be used to efficiently diagnose mgCSVD in Japanese patients.