55 - Alcoholism

Alcoholism

© SPMM Course  There appears to be as much variability in the phenotypic symptom expression within monozygotic twins as between MZ pairs. This suggests non-genetic influences play an important role in determining the pattern of phenotype in autism (LeCouteur, 1996).  Risk for broader phenotype (delayed speech, reading/spelling difficulties, social reticence/awkwardness, poor social language abilities) in first-degree relatives and dizygotic twins: 30%. In monozygotic twins, the spectrum phenotype has 82% concordance. (All data excerpted from http://pediatrics.aappublications.org/content/113/5/e472)  ADHD  Risk to first-degree relatives: 15-60%, 2-6 relative risk  Risk to second-degree relatives: 3-9%, 0.5-0.8 relative risk  Heritability: ~70-80%  Risks are higher for male relatives and lower for female. It is unclear if recurrence risks are higher when the proband is female. Continuation of illness into adulthood may indicate increased risk to relatives. Personality disorders  The largest factor accounting for nearly 50% or more of the variation in most personality traits is nonshared, person-specific environmental variation.  Among personality disorders, antisocial PD has the highest heritability (60-70%).  Emotional dysregulation has high heritability among various features of borderline PD.  A variant of the tryptophan hydroxylase gene (which codes for the synthetic enzyme for serotonin) is associated with low 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid and suicide attempts in violent criminal offenders. Panic disorder  Lifetime prevalence of panic disorder (+/-agoraphobia) is around 4.7%.  In a metaanalysis of family studies, Hettema et al. (2001) found OR of 5 for panic disorder in firstdegree relatives (absolute risk 8-31%). Early onset panic disorder confers increased risk than lateronset disease. Nearly 17 fold increase in risk is seen if the onset is before 20 years compared to the only 6-fold increase in relatives of probands with onset after 20 years. The heritability is estimated to be around 0.43. Social phobia  The 10-fold increase in risk is seen in first-degree relatives of probands with generalized social phobia. Non-generalised discrete social phobia does not show familial transmission.  Specific phobias are 3-4 times more common in 1st degree relatives of probands (OR 4). Nevertheless, twin data suggest that individual-specific environmental influences are more important in the development of simple phobias. Alcoholism  Genetic influences play an important role in alcoholism: the risk in families may be 4 to 6 times higher than in the general population.