Chromosomal deletion more common in prison population.SCOTTSDALE, ARIZ ARIZ Arizona (old style) . -- A genetic abnormality known as 22q11 deletion syndrome deletion syndrome Clinical genetics Any of number of hereditary conditions caused by a major loss of chromosome segments; all are rare, often have microcephaly, and an IQ < 50 appears to occur more commonly among incarcerated inmates than might be expected, Victoria Harris, M.D., said at the annual meeting of the American Academy of Psychiatry and the Law.
The syndrome results from a "short arm" on chromosome 22 in region 11, and is associated both with velocardiofacial abnormalities and with DiGeorge syndrome DiGeorge Syndrome Definition
DiGeorge syndrome (also called 22q11 deletion syndrome, congenital thymic hypoplasia, or third and fourth pharyngeal pouch syndrome) is a birth defect that is caused by an abnormality in chromosome 22 and affects the baby's , explained Dr. Harris, who is with the University of Washington, Seattle.
This deletion syndrome is characterized by midline mid·line
A medial line, especially the medial line or plane of the body.
n the line equidistant from bilateral features of the head. structural abnormalities: The nose and ears are disproportionately long, and some patients also have cleft lip and palate Cleft Lip and Palate Definition
A cleft is a birth defect that occurs when the tissues of the lip and/or palate of the fetus do not fuse very early in pregnancy. abnormalities, leading to speech abnormalities, Dr. Harris said. There may also be a lack of "impulse control, and [they] are often not able to read the usual social cues. This impulse dyscontrol might explain why I've seen some of these people in jail."
In general, one-fourth of the patients with this syndrome have schizophrenia, she noted.
Dr. Harris looked at patients in the King County (Wash.) Correctional Facility and found that a large subset appeared to have midline abnormalities. In addition, generally "they were big people, but they seemed to lack muscle tone." They also had difficulties with overreaching for particular targets. For instance, if they were reaching for a pencil, they would reach too far, she noted.
Dr. Harris wondered whether 22q11 deletion syndrome and its associated schizophrenia were overrepresented o·ver·rep·re·sent·ed
Represented in excessive or disproportionately large numbers: "Some groups, and most notably some races, may be overrepresented and others may be underrepresented" among the inmates. "If you see five people with this in a year, is [it] too many people ... than you would expect to occur by chance?"
After assuming 15% of those incarcerated have schizophrenia and 25% of people with this syndrome have schizophrenia, she looked at the number of people incarcerated in this particular facility and compared it with the 1% occurrence of schizophrenia in the general population. "What you get is about one person per decade should be incarcerated at this particular county jail with 22q11 deletion syndrome and schizophrenia," so the amount in this jail is probably more than would be observed by chance, she said.
But even if physicians could test inmates for this syndrome, how could that information be used? Dr. Harris noted that in one court case involving a defendant with XYY syndrome, the court ruled that chromosomal abnormalities have not yet been established as a cause for behavior, echoing the findings of other courts.
"Conventional wisdom does support the hypothesis that there's a higher prevalence" of genetic abnormalities among inmates, she said. "I don't know how much higher, but because there's impulse dyscontrol and these people, as a group, don't respond to neuroleptics in" the same way as those with schizophrenia alone, "there's a reason these people might be incarcerated."
Nonetheless, "the risk-benefit ratio of looking at the prevalence in correction facilities doesn't fly because it's not clear how the general society would in fact benefit from this study," she added. "That issue has to be looked at."
BY JOYCE FRIEDEN
Associate Editor, Practice Trends