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Study: Missing DNA can promote childhood obesity


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I wonder if Chromosone 16 has anything to do with Cushing's????? As Childhood or Adult Onset? Like CAH or adult-onset CAH? Worth a read.

 

Study: Missing DNA can promote childhood obesity

 

By MALCOLM RITTER, AP Science Writer Malcolm Ritter, Ap Science Writer ? Sun Dec 6, 2:24 pm ET

NEW YORK ? Some children get severely obese because they lack particular chunks of DNA, which kicks their hunger into overdrive, researchers report.

 

The British researchers checked the DNA of 300 children who'd become very fat, on the order of 220 pounds by age 10. They looked for deletions or extra copies of DNA segments.

 

They found evidence that several rare deletions may promote obesity, including one kind they studied further and found in less than 1 percent of about 1,200 severely obese children.

 

That deletion, on chromosome 16, apparently causes trouble because it removes a gene that the brain needs to respond to the appetite-controlling hormone leptin, said Dr. Sadaf Farooqi of Cambridge University.

 

In her study, children with a chromosome 16 DNA deletion "have a very strong drive to eat," said Farooqi, who co-led the research. "They're very, very hungry, they always want to eat."

 

The work, reported online Sunday by the journal Nature, has already produced a real-world payoff. Farooqi said four children with the chromosome 16 deletion had drawn the attention of British child welfare authorities, who blamed the parents for overfeeding them.

 

"We were able to intervene" and get the parents of two children off the hook, and the other two cases are under discussion, she said.

 

That's happened before when the scientists uncovered genetic causes for severe childhood obesity, she said.

 

"It's a slightly unusual outcome of our research, but one we think is very important," she said.

 

While scientists had previously discovered particular genes that promote obesity when damaged, the new work looked at larger chunks of DNA that can span several genes. The chromosome 16 deletion includes nine genes.

 

Eric Ravussin, an obesity expert at the Pennington Biomedical Research Center in Baton Rouge, La., who wasn't involved in the study, said the work provides "a gold mine of information." That's because it identifies specific chromosome areas that scientists can explore to discover obesity-related genes, he said.

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An interesting follow up to previous article:

 

Science News Share Blog Cite Print Email BookmarkType 2 Diabetes Gene Predisposes Children to Obesity, Study Finds

ScienceDaily (Dec. 14, 2009) ? Pediatric researchers have found that a gene already implicated in the development of type 2 diabetes in adults also raises the risk of being overweight during childhood. The finding sheds light on the genetic origins of diabetes and may present an avenue for developing drugs to counteract the disease, which has been on the upswing in childhood and adolescence.

 

"It has been a bit of a mystery to scientists how or even if these adult diabetes genes function during childhood," said study leader Struan F.A. Grant, Ph.D., a researcher and associate director of the Center for Applied Genomics of The Children's Hospital of Philadelphia. "This finding suggests that there may be genetic activity during childhood that lays the foundation for the later development of type 2 diabetes."

 

Type 2 diabetes occurs either when the pancreas produces too little insulin, or when the body cannot efficiently use the insulin that is produced because the cells have become resistant. Formerly called adult-onset diabetes and still most common in adults, type 2 diabetes has been increasing sharply among children and teenagers.

 

Grant and study co-leader Hakon Hakonarson, M.D., Ph.D., director of the Center for Applied Genomics at Children's Hospital, investigated 20 gene variants, known as single nucleotide polymorphisms (SNPs), previously reported to be associated with type 2 diabetes. The researchers drew on a cohort of nearly 7,200 Caucasian children, aged 2 to 18 years, in an ongoing genome-wide association study of childhood obesity at Children's Hospital. Dividing the cohort randomly in half allowed the team to follow their discovery study with a replication study.

 

Researchers continue to unravel the complicated role of different diabetes-related genes in influencing body weight toward both lower and higher ends of the scale. The risk of developing type 2 diabetes in adulthood is often influenced by factors in the first year of life, including lower birth weight, as well as by higher body mass index (BMI) during childhood. Obesity is a well-known risk factor for type 2 diabetes.

 

A previous study earlier this year by the same study team found that another type 2 diabetes gene, CDKAL1, affects fetal growth and increases the likelihood that a baby will be underweight at birth.

 

The current study found that the gene HHEX-IDE does not affect birth weight, but makes it more likely that a child will become obese during childhood. The gene does not appear to predispose to obesity in adults, although by contributing to childhood obesity, it may set the stage for type 2 diabetes in adulthood.

 

Grant cautioned that HHEX-IDE accounts for only a small proportion of the genetic contribution to the risk of type 2 diabetes, so many other gene variants remain to be discovered. However, he adds, HHEX-IDE may represent an important underpinning of the disease. "Previously we thought that this gene affects insulin production during adulthood, but we now see that it may play an early role in influencing insulin resistance through its impact on body size during childhood," said Grant. "One implication is that if we can develop medicines to target specific biological pathways in childhood, we may be able to prevent diabetes from developing later in life."

 

The National Institutes of Health, the Cotswold Foundation and The Children's Hospital of Philadelphia supported this study.

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