[Early childhood development and risk factors in rural China: a cohort study].

Objective: To investigate the development status and risk factors of infants and toddlers in rural China. Methods: In this cohort study, 603 infants (6-12 months of age, Phase Ⅰ) in the rural areas of QinLing-Bashan (Qin-Ba) in Shaanxi were recruited in the control group that received no intervention from April 2013 to October 2015. Three follow-up visits were performed every six months (Phase Ⅱ(12-18 months of age), Phase Ⅲ (18-24 months of age) and Phase Ⅳ(24-30 months of age)). In all the 4 phases (Ⅰ-Ⅳ), general data of the children and the families were collected by questionnaires, early childhood growth and development were assessed by door to door visits, children's hemoglobin levels were determined by laboratory tests, and the cognitive and motor development screening was conducted by the Bayley Scales of Infant and Toddler Development. Logistic regression was used to analyze the risk factors affecting the development of infants and toddlers in rural areas and the data were analyzed in terms of risk factors from infants, guardians and family. Results: Phase Ⅱ, Phase Ⅲ and Phase Ⅳ survey recruited 497, 483 and 486 participants respectively. The incidences of cognitive impairment (mental development scores<80) in rural areas of southern Shaanxi were 13.4% (81/603) in Phase Ⅰ(6-12 months), 20.1%(100/497) in PhaseⅡ(12-18 months), 42.9% (207/483) in Phase Ⅲ(18-24 months) and 50.4%(245/486) in Phase Ⅳ(24-30 months) respectively, which showed a significant increase with age (χ(2)=233.40, P<0.01); the incidences of psychomotor impairment (psychomotor development scores<80) of Phase Ⅰ, Phase Ⅱ, Phase Ⅲ and Phase Ⅳ were 25.0% (151/603), 26.8% (133/497), 8.3% (40/483) and 11.9% (58/486), which showed a significant decrease with age (χ(2)=87.08, P<0.01). Multivariate logistic regression analysis showed that the leading risk factor of the cognitive development of 24-30-month-old children was the mothers' poor education background (≤9 years of school education) (OR=2.56, P<0.01), and the main risk factors affecting psychomotor development were the mothers' poor education background (≤9 years of school education) (OR=2.64, P<0.05) and growth retardation (OR=2.95, P=0.07). Conclusions: The early childhood development (especially cognitive development) in the rural areas of Qin-Ba in Shaanxi of China is not optimistic. More attention should be paid to the early childhood development in rural China, especially to the development of children from the mothers with poor education background.

Genetic and neuroradiological heterogeneity of double cortex syndrome.

Mutations in the X-linked doublecortin gene appear in many sporadic cases of double cortex (DC; also known as subcortical band heterotopia), a neuronal migration disorder causing epilepsy and mental retardation. The purpose of this study was to examine why a significant percentage of sporadic DC patients had been found not to harbor doublecortin mutations and to determine whether clinical features or magnetic resonance imaging scan appearance could distinguish between patients with and without doublecortin mutations. Magnetic resonance imaging scan analysis differentiated patients into the following four groups: anterior biased/global DC with doublecortin mutation (16 of 30; 53%), anterior biased/global DC without mutation (8 of 30; 27%), posterior biased DC without mutation (3 of 30; 10%), and limited/unilateral DC without mutation (3 of 30; 10%). The presence of these atypical phenotypes suggests that other genetic loci or mosaicism at the doublecortin locus may be responsible for this diversity of DC cases.

Characterization of mutations in the gene doublecortin in patients with double cortex syndrome.

Mutations in the X-linked gene doublecortin, which encodes a protein with no dear structural homologues, are found in pedigrees in which affected females show "double cortex" syndrome (DC; also known as subcortical band heterotopia or laminar heterotopia) and affected males show X-linked lissencephaly. Mutations in doublecortin also cause sporadic DC in females. To determine the incidence of doublecortin mutations in DC, we investigated a cohort of eight pedigrees and 47 sporadic patients with DC for mutations in the doublecortin open reading frame as assessed by single-stranded conformational polymorphism analysis. Mutations were identified in each of the eight DC pedigrees (100%), and in 18 of the 47 sporadic DC patients (38%). Identified mutations were of two types, protein truncation mutations and single amino acid substitution mutations. However, pedigrees with DC displayed almost exclusively single amino acid substitution mutations, suggesting that patients with these mutations may have less of a reproductive disadvantage versus those patients with protein truncation mutations. Single amino acid substitution mutations were tightly clustered in two regions of the open reading frame, suggesting that these two regions are critical for the function of the Doublecortin protein.