The Bardet-Biedl syndrome is a a syndrome characterized mainly by obesity, pigmentary retinopathy, polydactyly, mental retardation, hypogonadism, and renal failure in fatal cases.

The syndrome is named after Georges Bardet and Arthur Biedl.

Two forms have been identified:

Bardet-Biedl syndrome 1 (BBS1) has no linkage to chromosome 16
Bardet-Biedl syndrome 2 (BBS2) is mapped to markers on chromosome 16.

Laurence-Moon-Biedl syndrome and Laurence-Moon-Biedl-Bardet syndrome are no longer considered as valid terms in that patients of Laurence and Moon had paraplegia but no polydactyly and obesity which are the key elements of the Bardet-Biedl the syndrome. Laurence-Moon syndrome is a separate entity.

Major features

Eyes: Pigmentary retinopathy.
Hand and foot: Polydactyly.
Cardiovascular system: Hypertrophy of interventricular septum and left ventricle and dilated cardiomyopathy.
Gastrointestinal system: Fibrosis.
Urogenital system: Hypogonadism, renal failure, urogenital sinuses, ectopic urethra, uterus duplex, septate vagina, and hypoplasia of the uterus, ovaries, and fallopian tubes.
Growth and development: Mental and growth retardation.
Behavior and performance: Poor visual acuity and blindness.
Heredity: The syndrome is familial and is transmitted as an autosomal recessive trait. chromosome 3 locus appears to be linked to polydactyly of all four limbs, whereas chromosome 15 is associated with early-onset morbid obesity and is mostly confined to the hands, and chromosome 16 represents the "leanest" form.
Additional features: Obesity.

Cause

The detail biochemical mechanism that leads to BBS is still unclear. Recently, eight genes (BBS1 to BBS8) that are responsible for the disease when mutated have been cloned, and most of the gene products encoded by these BBS genes are located in the basal body and cilia of the cell. It has been postulated that these BBS gene products might involve in the cell signaling pathway in the cilia, and these signaling systems play an essential role in the normal development so that a malfunction in these systems causes the diverse pathological effects of the Syndrome.

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Obesity in Children and Adolescents: Guidelines for Prevention and Management
From Nurse Practitioner, 8/1/04 by Holcomb, Susan Simmons

The National Health and Nutrition Examination Survey, sponsored by the National Center for Health Statistics, found that the percentage of overweight and obese children and adolescents in the year 2000 was 15%. This figure has quadrupled from 1963 to 1970 when the percentage was 4% in children 6 to 11 years old and 5% in adolescents 12 to 19 years old. Even more alarming is the fact that the chance of overweight and obesity in children persisting into adulthood is 20% at 4 years old and 70% to 80% if the child is still obese or overweight into adolescence.1,2

The highest risk of overweight and obesity is found in African American females 12 to 19 years old. The second highest incidence of overweight and obesity is found in Hispanic males 12 to 19 years old.3

In children, overweight is defined as being between the 85th and 94th percentile for age/sexspecific body mass index (BMI), while obesity in children and adolescents is defined as being at or above the 95th percentile for age/sex-specific BMI ( see Figures: 2 to 20 Years: Girls Body Mass Index-for-Age Percentiles and "2 to 20 Years: Boys Body Mass Indexfor-Age Percentiles.)" The 85th percentile for BMI in children and adolescents is approximately equivalent to a BMI of 25 in adults, and a BMI in the 95th percentile is approximately equivalent to a BMI of 30 in an adult.3,4

* Obesity Complications

The importance of recognizing the problem of overweight and obesity in children and adolescents goes back to the risk of becoming an overweight or obese adult with all of the medical complications associated with these conditions. However, even before reaching adulthood, there is a current trend of children developing type 2 diabetes mellitus. There is also a three-fold increase for the development of hypertension as an adult, although there is now an increasing number of children and adolescents diagnosed with hypertension.5 Overweight and obesity are also linked to an increase in asthma and obstructive sleep apnea. Besides hypertension, other cardiovascular concerns . include dyslipidemia, left ventricular hypertrophy, and metabolic syndrome.5 In fact, if an adolescent's BMI is greater than or equal to the 75th percentile-well below the current definition of overweight6-there is a risk of dying from cardiovascular disease as an adult.

Other complications of childhood and adolescent overweight and obesity include orthopedic problems, especially in weight bearing joints, and psychosocial problems. Poor self-esteem may result from teasing at school, leading to isolation and more eating if the child is bored and/or depressed.5

* Risk Factors

Risk factors associated with childhood and adolescent overweight and obesity include high birth weight, maternal diabetes, and family history of obesity. If one parent is obese, there is a three-fold increase for the child to become obese in adulthood. If both parents are obese, the risk is 10 times or greater. Before age 3, parental weight is more of a risk factor for developing obesity than the child's actual weight.5

During adolescence, some insulin resistance occurs, typically during the growth spurt, potentially increasing the chances of a child already susceptible to obesity to acquire the disease.

Early menarche is also associated with obesity (two-fold) if the child's BMI is greater than the 85th percentile.5

Low income, low education, absence of family meals, and sedentary behavior are also linked with the development of overweight and obesity in children. Currently, an estimated 20% of children in the United States have two or less sessions of physical activity each week. It is also estimated that about onequarter of U.S. children watch 4 or more hours of television daily and 43% of adolescents watch television for at least 2 hours per day. Even more hours are spent watching television if the set is in the child's room.2

* Disorders

There are some inherent disorders associated with overweight and obesity in children, although their incidence is less than the incidence of risk factors. Endocrine problems associated with the development of overweight and obesity include hypothyroidism, Cushing's disease, and primary hyperinsulinemia. Genetic syndromes include PraderWilli syndrome, Bardet-Biedl syndrome, Cohen's syndrome, and Turner's syndrome.5

Recently, a study at Harvard followed 8,203 9 to 14 year old children and found that calorie-restrictive diets in children may actually be counterproductive; children who diet regularly gain weight rather than lose weight.5 This may be a result of changes in metabolism resulting from binge eating. Binge eating in response to caloric restriction appears to be more common in girls than boys. The recommendation from this study was to have children adopt good eating habits without severe calorie restrictions and to encourage physical activity. Another suggestion was to aim for a moderate weight loss of around 1 pound a month, which equates to approximately 100 calories less intake daily.

* Dietary Guidelines

Dietary guidelines should lean toward "wholesome" diets.7 Only 2% of school-age children currently meet the number of servings suggested in the Food Guide Pyramid. "Wholesome" indicates more fresh fruits and vegetables, whole grains, legumes, and nonprocessed foods. "Five a day" should be the rule with fruits and vegetables. Increasing water and low-fat or nonfat milk intake instead of sugary drinks and sodas should be encouraged. Also, limiting snacks to 150 calories or less may help curb food intake.3

Meals should not be skipped and food should not be used as a reward or withheld as a punishment. Family meals at a table and not in front of the television should be encouraged. At school, children should be allowed adequate time to eat and be able to eat in a pleasant environment.1 Children can be taught that it is okay to leave food on their plate if they are full. Parents should guide the eating habits of their children and primary care providers can intervene with nutritional education when warranted.

The standard United States Department of Agriculture (USDA) school lunch must now contain less than 30% of calories from fat. Even though 88% of schools participate in the USDA lunch program, one-quarter of schools sell high-fat, brand-name foods as well as the USDA lunch. Schools also do not have to follow USDA guidelines for foods sold a la cart, in snack bars, or in vending machines.

* Other Recommendations

In January 2004, the American Academy of Pediatrics urged the restriction of soft drink sales in schools.8 At least 85% of school-aged children drink one soft drink daily, which contains 150 calories and 10 teaspoons of sugar in each 12-ounce can. However, 3% to 7% of children 6 to 8 years of age, 21% of children 9 to 13 years of age, and 32% to 52% of children 14 to 18 years of age have three or more soft drinks daily. In addition, 58% of elementary schools and 94% of high schools have soft drink vending machines.

A major recommendation to reduce weight in children is to turn off the television. Coupled with inschool sitting, there are not enough hours before bedtime to exercise, but plenty of hours to eat. It is recommended that schools promote physical education programs that emphasize daily activities for personal fitness, leading to overall lifestyle changes, rather than emphasize team sports.5

The Centers for Disease Control and Prevention (CDC) sponsors a program called VERB, which encourages young people ages 9 to 13 to be physically active every day. The campaign combines paid advertising, marketing strategies, and partnership efforts to reach the distinct audiences of adolescents and adults/influencers. VERB promotes physical activity in and out of schools and in the fall, urges kids to use the extra hour gained when the clocks are turned back for exercise.

* School Involvement

Prohibiting junk food advertisements in schools has been recommended as well as banning junk food sales. Removing soft drink vending machines has also been proposed. A group called Childhood Obesity Prevention Campaign suggests that schools should be awarded extra funding when they exceed federal nutritional standards.

Unfortunately, school districts may be reluctant to ban vending machines because revenue for the school is made on their use. Perhaps changing the vending machine contents to alternatives that are more wholesome could be initiated.

Currently, weight loss medications and surgery, although used for obese adults, are not Food and Drug Administration (FDA)-approved for children.6 Behavior modification may be a good approach in addition to changing diet habits and encouraging exercise.9

As nurse practitioners, we are in a wonderful position to help educate parents and children regarding diet and exercise, as well as help with the maintenance of appropriate weight and identification of children at risk for overweight and obesity.

REFERENCES

1. The Center for Health and Health Care in Schools. Childhood Obesity: What the Research Tells Us. 2003. Retrieved May 26, 2004, from http://www.healthinschools.org.

2. The Surgeon General (ND). The Surgeon General's Call to Action to Prevent and Decrease Overweight and Obesity: Overweight in Children and Adolescents. Retrieved May 26, 2004, from http://www.surgeongeneral.gov/topics/ obesity/calltoaction/fact_adolescents.htm.

3. Best Practice Group. Best Practices in the Diagnosis and Treatment of Childhood Obesity. Metropolitan Health Council: Kansas City, MO: 2003.

4. Centers for Disease Control and Prevention. BMI for Children and Teens. April 8, 2003. Retrieved May 26, 2004, from http://www.cdc.gov/ nccdphp/dnpa/bmi/bmi-for-age.htm

5. American Academy of Pediatrics. Prevention of pediatric overweight and obesity. Pediatrics 2003;112(2),424-30.

6. Kiess W, Bottner A, Bluher S, et al: Pharmacoeconomics of obesity management in childhood and adolescence. Expert Opinions in Pharmacotherapy 2003, 4(9), 1471-1477.

7. USDA. Nutrition and Your Health: Dietary Guidelines for Americans. May 24, 2004. Retrieved June 23, 2004 at http://www.health.gov/dietaryguidelines.

8. Markel H: Soft drinks, schools, and obesity. Medscape Pediatrics 2004, 6(1). Retrieved March 17, 2004, from http://www.medscape. com/viewarticle/470344_print.

9. Moran R: Evaluation and treatment of childhood obesity. Am Fam Phys 1999 Feb 15;59(4):758, 761-2. Retrieved May 26, 2004, from http://www.aafp.org/afp/990215ap/861. html.

Susan Simmons Holcomb, PhD, ARNP, BC

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