Objective To explore the changes of white matter microstructure by using DTI in children with developmental delay (DD)with normal routine MRI results.Methods We performed routine MRI and DTI in 23 children with DD and 23 age-matched normal children,FA values of five deep white matters (limb of internal capsule,anterior limb,genu and knee of corpus callosum and optic radiation)and four shallow white matters (frontal lobe,temporal lobe,occipital cortex,centrum ovale)were measured.FA values of the white matter for two groups were assessed by paired t tests for each region of interest.Results FA values on the deep white matter for DD,and on the deep white matter and the shallow white matter for normal development group increased with age significantly (P <0.05).FA values on the shallow white matter for DD were lower than that for normal development group,which had no significant correlation with age (P >0.05).The FA values on the shallow white matter and deep white matter (corpus callo-sum knee,optic radiation)for children with DD were lower than that for the control group (P <0.05),and the FA values of the limb of deep white matter (genu of corpus callosum,internal capsule and anterior limb)were no difference with the contorl group (P >0.05).Conclusion DTI may detect the changes of white matter microstructure in children with developmental delay,and provides an objective basis for quantitative diagnosis.

Purpose To investigate the correlation between the brain white matter changes of MR diffusion tensor imaging (DTI) and cognitive function in the patients with mild cognitive impairment. Materials and Methods The patients (40 cases) were classified into two groups:group A (20 patients with ischemic foci in the deep white matter ) and group B (20 patients without ischemic foci in the deep white matter), and 20 normal controls was enrolled. Conventional MRI, DTI, mini-mental state examination (MMSE) and montreal cognitive assessment (MoCA) were applied, then fractional anisotropy (FA) value and apparent diffusion coefficient (ADC) value were compared among three groups. The scores of MoCA was analyzed between the patient groups. Results The decreased FA value, increased ADC value and decreased MoCA scores was demonstrate in group A, and showed significant difference compared with group B (t=-4.229,-3.251,-7.533,-2.702,-2.660;P<0.05). The increased ADC value and decreased FA value in the frontal and hippocampus region were detected in group B compared with normal controls (t=-7.790,-2.785,-4.415,-5.164;P<0.05). Conclusion The early and special structural changes can be detected using DTI compared with conventional MRI. The severe white matter lesions can be demonstrated in the patients with ischemic foci in the deep white matter, who is prone to dementia.

To unravel the genetic mechanisms of disease and physiological traits, it requires comprehensive sequencing analysis of large sample size in Chinese populations. Here, we report the primary results of the Chinese Academy of Sciences Precision Medicine Initiative (CASPMI) project launched by the Chinese Academy of Sciences, including the de novo assembly of a northern Han reference genome (NH1.0) and whole genome analyses of 597 healthy people coming from most areas in China. Given the two existing reference genomes for Han Chinese (YH and HX1) were both from the south, we constructed NH1.0, a new reference genome from a northern individual, by combining the sequencing strategies of PacBio, 10× Genomics, and Bionano mapping. Using this integrated approach, we obtained an N50 scaffold size of 46.63 Mb for the NH1.0 genome and performed a comparative genome analysis of NH1.0 with YH and HX1. In order to generate a genomic variation map of Chinese populations, we performed the whole-genome sequencing of 597 participants and identified 24.85 million (M) single nucleotide variants (SNVs), 3.85 M small indels, and 106,382 structural variations. In the association analysis with collected phenotypes, we found that the T allele of rs1549293 in KAT8 significantly correlated with the waist circumference in northern Han males. Moreover, significant genetic diversity in MTHFR, TCN2, FADS1, and FADS2, which associate with circulating folate, vitamin B12, or lipid metabolism, was observed between northerners and southerners. Especially, for the homocysteine-increasing allele of rs1801133 (MTHFR 677T), we hypothesize that there exists a "comfort" zone for a high frequency of 677T between latitudes of 35-45 degree North. Taken together, our results provide a high-quality northern Han reference genome and novel population-specific data sets of genetic variants for use in the personalized and precision medicine.