Increased symptoms of attention deficit hyperactivity disorder and major depressive disorder symptoms in Nail-patella syndrome: potential association with LMX1B loss-of-function.

Nail-Patella syndrome (NPS) is an autosomal dominant disorder that is the result of heterozygous loss-of-function mutations in LMX1B, coding for a LIM homeobox (LIM-HD) transcription factor. Analyses of lmx1b mutant mice have revealed the role of Lmx1b in the development of mesencephalic dopaminergic neurons and the serotonergic system; these areas have been linked with symptoms of attention deficit hyperactivity disorder (ADHD) and major depressive disorder (MDD). Fifty adults (38 females, 12 males) with NPS completed the Conners' Adult ADHD Rating Scales-Self-report: Long Version (CAARS) and Beck Depression Inventory-II (BDI-II). The objective was to describe the neurobehavioral phenotype of these subjects and examine possible relationships between neurobehavioral symptoms and NPS. Elevated levels of DSM-IV-TR ADHD Inattentive symptoms were reported on the CAARS by 22% of the NPS sample. The BDI-II Total score was elevated for 40% of the NPS sample. There was a significant increase in the odds of an elevated BDI-II Total score when any of the three CAARS scales were elevated (odds ratios ranging from 11.455 to 15.615). The CAARS and BDI-II did not significantly differ with gender, age, or education level. There was no significant association between genetic mutation-predicted protein status and elevations on CAARS or BDI-II. Individuals with NPS reported co-occurring symptoms of ADHD and MDD, with higher levels of co-occurrence than reported in the literature for the general population. The co-occurrence of these symptoms may be related to mesencephalic dopaminergic neurologic pathway abnormalities that are a consequence of LMX1B loss of function.

Contributions of parental alcoholism, prenatal substance exposure, and genetic transmission to child ADHD risk: a female twin study.

BACKGROUND: Genetic influences have been shown to play a major role in determining the risk of attention-deficit hyperactivity disorder (ADHD). In addition, prenatal exposure to nicotine and/or alcohol has also been suggested to increase risk of the disorder. Little attention, however, has been directed to investigating the roles of genetic transmission and prenatal exposure simultaneously. METHOD: Diagnostic telephone interview data from parents of Missouri adolescent female twin pairs born during 1975-1985 were analyzed. Logistic regression models were fitted to interview data from a total of 1936 twin pairs (1091 MZ and 845 DZ pairs) to determine the relative contributions of parental smoking and drinking behavior (both during and outside of pregnancy) as risk factors for DSM-IV ADHD. Structural equation models were fitted to determine the extent of residual genetic and environmental influences on ADHD risk while controlling for effects of prenatal and parental predictors on risk. RESULTS: ADHD was more likely to be diagnosed in girls whose mothers or fathers were alcohol dependent, whose mothers reported heavy alcohol use during pregnancy, and in those with low birth weight. Controlling for other risk factors, risk was not significantly increased in those whose mothers smoked during pregnancy. After allowing for effects of prenatal and childhood predictors, 86% of the residual variance in ADHD risk was attributable to genetic effects and 14% to non-shared environmental influences. CONCLUSIONS: Prenatal and parental risk factors may not be important mediators of influences on risk with much of the association between these variables and ADHD appearing to be indirect.