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Dopamine D4 receptor (DRD4) polymorphism and adaptability trait during infancy: a longitudinal study in 1- to
A De Luca1, M Rizzardi, I Torrente
1Dipartimento di Biopatologia e Diagnostica per Immagini, Sezione di Genetica, Università di Roma Tor Vergata, Via di Tor Vergata 135, 00133 Rome, Italy.
Insights
The dopamine D4 receptor (DRD4) gene influences infant temperament, specifically adaptability. Long DRD4 alleles correlated with lower adaptability scores in newborns, highlighting early genetic effects on behavior.
Area of Science:
- Behavioral Genetics
- Neuroscience
- Developmental Psychology
Background:
- The dopamine D4 receptor (DRD4) gene is implicated in various behavioral traits.
- Infant temperament is a foundational aspect of personality development.
- Understanding early genetic influences on behavior is crucial for developmental research.
Purpose of the Study:
- To investigate the association between the DRD4 exon III repeat polymorphism and infant temperament.
- To assess behavioral differences in neonates at 1 and 5 months of life.
- To determine the genetic contribution to infant adaptability.
Main Methods:
- Study included 122 Italian neonates assessed at 1 and 5 months.
- Temperament was measured using the Italian versions of the Early and Revised Infancy Temperament Questionnaires (EITQ/RITQ).
- Two-way analysis of variance (genotype x age) was employed to analyze the data.
Main Results:
- A significant correlation was found between DRD4 genotype and the temperamental subscale of adaptability.
- Infants with long (L) DRD4 alleles showed significantly lower adaptability scores at 1 month compared to those with short (S) alleles.
- These genotype-related differences in adaptability diminished by 5 months, suggesting environmental influences.
Conclusions:
- The DRD4 gene significantly influences human temperament at birth, particularly adaptability.
- Early infant behavior shows a stronger genetic component related to DRD4.
- Environmental factors play a substantial role in shaping temperament as infants mature.
Abstract:
We have examined the relationship between the common dopamine D4 receptor (DRD4) exon III repeat polymorphism and infants' behavior measured with the Italian version of the Early and Revised Infancy Temperament Questionnaires (EITQ/RITQ) in 122 Italian neonates at 1 and 5 months of life, when the genetic contribution to the behavior can be more clearly assessed. Two-way (genotype x age) analysis of variance revealed a significant correlation with the temperamental subscale of adaptability [F(1, 120) = 5.26, P < 0.02]. At 1 month of life (early assessment), infants with long (L) DRD4 alleles presented significantly low scores (L 2.61 +/- 0.073; S 2.84 + 0.79; Newman-Keuls P = 0.03) in comparison with the high scores of infants with short (S) alleles (L 2.4 +/- 0.059; S 2.25 +/- 0.57). These differences were not detected at 5 months of life (late assessment), denoting a strong environmental effect at this age on the genetic background. These results confirm and extend the genetic influence of the DRD4 gene in human temperament at birth.