臍帶血鉛、VDR-FokI多型性與兒童兩歲的神經發展

Abstract

Lead may produce adverse effects on the nervous system and influence cognition, memory and intelligence. Even with low dose exposure, lead may still have adverse effects on humans, especially infants and pregnant women. Genetic polymorphism may play an important role in modulating the health effects, but there have been few studies about the relation between genetic polymorphism and infant neurobehavioral development. The objective of this study was to explore the modifier effect of VDR FokI polymorphism on lead exposure and early childhood neurodevelopment. Our study subjects were pregnant women and their neonates in the pilot study of Taiwan Birth Panel Study (TBPS) conducted between April 2004 and January 2005. We collected neonatal umbilical cord blood at delivery for lead analysis. The cord blood lead concentration was detected by ICP-MS. We obtained information on relevant confounding factors by personal interview based on a structured questionnaire. The Comprehensive Developmental Inventory for Infants and Toddlers (CDIIT) and Infant/Toddler HOME of Home Observation for Measurement of the Environment Inventory (IT-HOME) were used to evaluate infant neurobehavioral development at six months of age. The second evaluation was performed when children were twenty-four months of age. VDR genetic polymorphisms were analyzed by real-time PCR method. The mean cord blood lead levels was 1.3 ug/dl and the VDR FokI genetic type rates were 21% for TT, 54% for CT and 24% for CC. Subjects with high lead exposure (> 1.64 ug/dl) had lower 5.85 scores in cognitive domain than subjects with low lead exposure (<= 1.64 ug/dl). Further, our analyses suggest that as cord blood lead increased, the scores of children with CT and CC genotype declined significantly (6.83 scores) in social domain compared with children who carried TT genotype. However, language scores were significantly lower in children with VDR FokI polymorphism regardless of lead levels. Overall, VDR FokI polymorphism may have a modifier effect on the neurobehavioral development of children who have lead toxicity.