Objective To evaluate the association between methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism and depression risk.Methods Available studies containing genotype frequencies of MTHFR C677T were chosen,and pooled odds ratio (OR) with 95％ confidence interval (CI) was used to assess the strength of the association.Results Twenty-five eligible studies including 4 048 cases and 12 827 controls were identified.Meta-analysis showed a significant effect in the co-dominant model (T vs.C:OR 0 =1.25; Z=3.82,P=0.000;TTvs.CC:OR1=1.55,Z=3.79,P=0.000 ; except CT vs.CC:OR2=1.13; Z=1.78,P=0.076).Stratified analysis denoted that there was significantly higher risk in depression onset before 60 years old than depression onset after 60 years old.In subgroup analysis stratified by regressive meta-analysis,MTHFR C677T variant was statistically significantly relevant to depression risk in Chinese populations (OR 0 =1.58,Z=3.95,P=0.000; OR 1 =2.55,Z=3.92,P=0.000; OR 2 =1.43,Z=2.72,P=0.007),but not in no-Chinese populations (OR 0 =1.12,Z=2.10,P=0.035 ; OR 1 =1.23,Z=2.23,P=0.025 ; OR 2 =1.06,Z=0.74,P=0.456).Evidentiary strength rated by GRADE showed that 1 study moderate,3 studies low and 7 stdudies very low.Conclusion Our study provides evidence for a hereditary association between the MTHFR C677T variant and depression susceptibility,whereas there is an obvious variety in different regions,ethnicities and onset age.

Bilateral medial medullary infarction(MMI)was a rare subtype of stroke.The clinical manifestations of bilateral MMI were complicated,which leaded to misdiagnosis.Patients with bilateral MMI could progress rapidly,and were easy to progress to respiratory failure and even death.Patients with this type of cerebral infarction did not respond well to medication.One case data of a patient with bilateral MMI was reviewed and analyzed.The weakness on the right side of the body was presented,accompanied by slurred speech,and was finally diagnosed with atherosclerosis of the large arteries through cranial MR examination.The patient had occlusion of the left posterior inferior cerebellar artery distal to the left vertebral artery V4 segment on the left side.The patient was treated with stent thrombectomy and balloon angioplasty,and the follow-up phone call at 3 months after discharge was showed good prognosis.Through a review of the literature,combined with the clinical and imaging features of this case,a preliminary analysis suggested that atherosclerosis of the large arteries may be the most common cause of bilateral MMI.Cranial MR imaging is an important method for diagnosing this condition.For patients with bilateral MMI accompanied by occlusion of the vertebral artery V4 segment,endovascular intervention may be attempted.