Phelan-McDermid Syndrome Week draws attention to rare genetic disorder

It is possible that every week in a 52 week year is named in honor of one or more disease or illness.

The week of July 21-27, however, has extra meaning for Katy Phelan, PhD, FACMG, and director of the cytogentics laboratory at Molecular Pathology Laboratory Network, Inc., in Maryville.

Next week is Phelan-McDermid Syndrome Week in recognition of a rare genetic disorder. Phelan identified the 22q13 deletion and created a support group for families and their children with the disease.

“There are hundreds of families in the U.S. and around the world with children diagnosed and undiagnosed with the Phelan-McDermid syndrome,” said Phelan,

“It is the hope of these families to raise awareness about the disorder and its symptoms so appropriate treatment and care can be provided much earlier.”

The recognition of Phelan-McDermid week came through the efforts of mothers and fathers in the Phelan-McDermid Syndrome Support Group in Tennessee, Georgia, Alabama, South Carolina and beyond who wrote and called their state representatives, senators and governors requesting that proclamations be written and presented to recognize July 21-27 2008, as Phelan-McDermid Syndrome Week and May 19, 2008, as Phelan McDermid Syndrome Day.

“So far, the families have received tremendous support from their elected officials,” Phelan said. “These proclamations and presentations have generated valuable attention for the Phelan-McDermid Syndrome and help our efforts to spread the word about this rare disorder.”

May 19 marked the 20th anniversary of Phelan discovering the 22q13 deletion while working at a lab in Greenville, S.C. State Rep. Doug Overbey presented the proclamation proclaiming Phelan-McDermid Syndrome Day.

“We recognize Dr. Phelan for her tireless work in identifying this disorder,” Overbey said.

Kathleen and Stephen Wermuth, a Blount County couple whose 10-year-old daughter Stephanie was diagnosed with the Phelan-McDermid syndrome when she was 18 months old, was with Phelan at the proclamation presentation.

The Wermuths moved to this area from Boston. “We’re so glad we chose Tennessee to be our new home,” Kathleen Wermuth said.

When they left Boston, they didn’t know what they would encounter when they moved. “We knew no one other than Dr. Phelan,” she said. “It’s been a great blessing. We have a great support system here.”

“This much needed recognition is hopefully just the beginning of bringing the Phelan-McDermid Syndrome more to the forefront of healthcare discussions and considerations. The more people know about it, the better the medical community can care for children and families,” Phelan said.

The Phelan-McDermid Syndrome, a rare genetic anomaly caused by the absence of genes at the tip of the long arm of chromosome 22, plays a pivotal role in the development of the human nervous system, including the brain.

In 1988, Phelan identified the 22q13 deletion while performing chromosome analysis at the Greenwood Genetic Center in Greenville, S.C., on a newborn whose distinguishing characteristic was hypotonia or poor muscle tone.

In 1992, Phelan published an article in the American Journal of Medical Genetics called “Cytogenetic, Biochemical and Molecular Analysis of a 22q13 Deletion” outlining her findings.

According to website of the Phelan-McDermid Syndrome and 22q13 Deletion Foundation, by the 2002 conference, membership had moved well past the 100 mark and about 40 families attended including ones from Brazil, England, Ireland, Canada and many of the lower 48 states.

At that conference, Dr. Heather McDermid of the University of Alberta in Canada, announced a breakthrough in determining the cause of children’s’ chromosomal deletion. Dr. McDermid said she had narrowed the cause affecting children’s neurological functions to a gene now known as SHANK3.

“Since the Phelan-McDermid Syndrome diagnosis is so rare and somewhat new, our support group is a critical resource for helping families worldwide to cope with a life-changing experience. Through an exchange of ideas, tips and information we try to calm parents’ fears and steer them on a path that will enrich their child’s life. The close-knit feelings our members have for each other make our international support group conferences feel more like a family reunion,” said Nick Assendelft, vice president of the 22q13 Deletion Syndrome Foundation, which began in 2002.

Roger Hubbard, PhD, founder, president and CEO of MPLN, said not only was Phelan instrumental in discovering the syndrome, “She’s been integral in creating the support system.”

Kathleen Wermuth said she and her husband knew something was wrong when Stephanie was 8 to 9 months old. She wasn’t sitting or grabbing at things like other babies her age. “We went to the pediatrician and said we thought something was wrong. She’s not hitting milestones,” she said.

It took nine months before they learned what was wrong. “It was nerve-wracking not knowing what it was. For us, we think it’s better to know,” she said.

There is a wide range of symptoms associated with the deletion, but most individuals exhibit moderate to severe developmental delays, absent or severely delayed speech, normal to accelerated growth and atypical physical features. Very low muscle tone is a common trait, and many individuals rollover, sit, crawl and walk at a later age than usual.

“Facial features such as a long head shape, puffiness around the eyes, long eyelashes, droopy eyelids, puffy cheeks and large ears are fairly subtle and may not be recognized by a physician,” Phelan said. “That is why it is so important to educate the medical community about this rare disorder so that families can obtain the care and help they need as early as possible.”

Other physical features include large, fleshy hands, webbing of the second and third toes, underdeveloped toenails that may peel off effortlessly, sacrel dimple and the inability to perspire, readily causing overheating. Behavioral characteristics include mouthing or chewing non-food items, increased tolerance for pain and autistic-like effects.

Approximately 500 cases of this deletion have been diagnosed worldwide. More than 30 percent of cases have required chromosome analysis two or more times before the deletion was detected. Still, many children go undiagnosed, often thought to have Angelman Syndrome, a condition with many features similar to Phelan-McDermid Syndrome, said Phelan. The development of a molecular crytogenetic procedure called fluorescence in situ hybridization (FISH), performed at MPLN, facilitates the identification of the deletion on chromosome 22.

Outreach to find and help these families and others not yet diagnosed was one of Phelan’s objectives after her discovery. In the years following her initial publication, families whose children were diagnosed with the disorder contacted Phelan. Thereafter, Phelan established a network of families with the goal of forming a parent support group. This year, more than 100 families worldwide are expected to attend the support group conference set for July 25-27 in Greenville, S.C.

For more information about the Phelan-McDermid Syndrome or support group, visit

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