Suicidal ideation in Huntington disease: the role of comorbidity.

Huntington disease (HD) is a neurodegenerative condition characterized by cognitive impairments, motor abnormalities, and psychiatric disturbance. An increased risk for suicide has been documented. The majority of HD research has focused on cognitive and motor features of HD; the implications of psychiatric manifestations have received less consideration. Recent studies have sought to identify the stages of HD in which patients are at increased risk to experience suicidal ideation, though no study has examined possible risk factors for suicidality. The current study examines the presence of psychiatric comorbidity and its involvement in suicidal ideation. Suicidal ideation was examined in 1941 HD patients enrolled in the Huntington Study Group. Of those, 19% (N=369) endorsed current suicidal ideation. Logistic regression analyses indicated that depression/anxiety and aggression/irritability are significant predictors of suicidal ideation. In a subsample with the greatest suicidal ideation, alcohol and drug abuse were also predictive. It is recommended that all individuals with HD (specifically those with features of depression, aggression, substance abuse) have routine suicide assessment; further research is needed to understand the high rate of suicide in HD.

aCGH detects partial tetrasomy of 12p in blood from Pallister-Killian syndrome cases without invasive skin biopsy.

Pallister-Killian syndrome (PKS) is a genetic disorder characterized by mental retardation, seizures, streaks of hypo- or hyperpigmentation and dysmorphic features. PKS is associated with tissue-limited mosaic partial tetrasomy of 12p, usually caused by an isochromosome 12p. The mosaicism is usually detected in cultured skin fibroblasts or amniotic cells and rarely in phytohemagluttinin-stimulated lymphocytes, which suggests stimulation of T-lymphocytes may distort the percentage of abnormal cells. We recently reported on the identification by microarray-based comparative genomic hybridization (aCGH) of a previously unsuspected case of partial tetrasomy of 12p caused by an isochromosome 12p. Here we report on seven additional individuals with partial tetrasomy of 12p characterized by our laboratory. All individuals were referred for mental retardation/developmental delay and/or dysmorphic features. In each case, aCGH using genomic DNA extracted from whole peripheral blood detected copy-number gain for all clones for the short arm of chromosome 12. In all but one case, FISH on metaphases from cultured lymphocytes did not detect the copy-number gain; in the remaining case, metaphase FISH on cultured lymphocytes showed an isochromosome in 10% of cells. However, interphase FISH using probes to 12p on peripheral blood smears showed additional hybridization signals in 18-70% of cells. Microarray and FISH analysis on cultured skin biopsies from four individuals confirmed the presence of an isochromosome 12p. Our results demonstrate the usefulness of aCGH with genomic DNA from whole peripheral blood to detect chromosome abnormalities that are not present in stimulated blood cultures and would otherwise require invasive skin biopsies for identification.