NEWS-Gene Linked to Early-Onset

[Judith Richards <judithr@xxxxxxxx>]

Gene Linked to Early-Onset Parkinson's Disease

 NEW YORK, May 26, 2000 (Reuters Health) - Mutations in the parkin gene
can cause Parkinson's disease to develop early in life, but the symptoms
of this early-onset form of the disease do not differ from the later
developing illness.

Parkin gene mutations have only recently been linked to Parkinson's
disease in younger individuals, so the frequency of the mutations and
the manifestations of this form of the disease have not been studied
previously, according to Dr. Christoph Lucking from Hopital de la
Salpetriere in Paris, France and an international team of researchers.

The authors studied 73 families with early-onset, inherited Parkinson's
disease (including 152 affected family members), as well as 100 other
patients whose early-onset Parkinson's disease did not appear to be
inherited.

Nearly half of the families with early-onset Parkinson's disease (PD)
showed mutations in their parkin genes, the authors report, whereas 18%
of the patients with isolated early-onset PD had parkin gene mutations.
In both groups of patients, two abnormal parkin genes appeared to be
required for PD to develop. Geneticists called such diseases autosomal
recessive, meaning that an affected gene is inherited from each parent.

Patients who carried abnormal parkin genes were younger
when their disease developed, and they were more likely to
show abnormalities in muscle tone and reflexes than their
normal-parkin-gene counterparts, the report in the May 25th
issue of The New England Journal of Medicine indicates.

Once PD developed, patients with parkin gene mutations were more likely
than those without mutations to improve with medical therapy, the
researchers note, although they were also more likely to experience side
effects from the drug levodopa.

Despite these differences, the investigators suggest, physical
examinations and symptoms were not specific enough to be able to
distinguish patients with mutations from patients without mutations.

A wide variety of parkin genes was detected by specific testing, the
researchers say, but a relatively simple screening test should detect
70% of the parkin mutations that cause Parkinson's disease.

"Mutations in the parkin gene are a major cause of early-onset autosomal
recessive familial Parkinson's disease and isolated juvenile-onset
Parkinson's disease (at or before the age of 20 years),'' the authors
conclude.

The results also suggest ``...that among patients who are older than 30
years at the onset of isolated (that is, not familial) Parkinson's
disease, the disease is mainly due to causes other than parkin
mutations,'' the authors add.

SOURCE: The New England Journal of Medicine 2000;342:1560-1567.
 Copyright © 2000 Reuters Limited.

--
Judith Richards, London, Ontario, Canada
judithr@xxxxxxxx
                        Today?s Research...
                                Tomorrow?s Cure