Managing Early-Onset Weight Problems in Children with a Rare Disease: Why Timing Matters

Addressing stigma and fostering family engagement

Removing the stigma surrounding a child’s severe and early-onset weight issues (often before age five) is key to engaging families in holistic lifestyle changes. Improving the family’s understanding of the underlying causes of their child’s weight problems fosters better collaboration with healthcare professionals.

Consistent, supportive messaging from the entire care team — GPs, paediatricians, geneticists, and sub-specialists (including endocrinologists, neurologists, and nephrologists) — is essential for effective management.

Even when the specific cause of a child’s rare genetic disease is unknown, acknowledgement from healthcare professionals that there is no blame or shame associated with the child’s weight can be a significant relief for families.

Understanding the connection between rare diseases and obesity

According to Rare Voices, a disease is rare if it affects less than five in 10,000 people. While there are more than 7,000 known rare diseases, many do not cause obesity in children.

Examples of rare diseases associated with obesity

In this section, we highlight some rare diseases that contribute to weight gain due to hormonal imbalances, metabolic disorders, and genetic syndromes. The aim is to raise awareness of such rare diseases, so you have a better understanding of the potential implications.

Prader-Willi Syndrome (PWS)

Prader-Willi Syndrome is a rare genetic disease, affecting one in 10,000 to 20,000 born with the condition. It’s a disease that leads to an increased appetite and slower metabolism, creating the perfect scenario for weight gain and obesity to develop. Children with PWS often  also have neurodevelopmental delay with low muscle tone and various hormonal deficiencies, including thyroid and growth hormone deficiency that require treatment for optimal growth.

Along with Rare Voices, the Prader-Willi Syndrome Association of Victoria and the Prader-Willi Research Foundation of Australia RVA Partner are fantastic resources for further information on this rare condition.

PWS impacts weight gain in children as the disease causes an insatiable appetite. Children with PWS feel the urge to eat constantly, which naturally leads to weight gain and the potential to become obese.

An odd symptom of PWS is an inability to feel full, even after consuming large quantities of food. This symptom develops early on in childhood, usually following an initial period of poor feeding in infancy with poor muscle tone.

Bardet-Biedl Syndrome (BBS)

Bardet-Biedl Syndrome (BBS) is a rare genetic condition that affects how the body regulates appetite, weight, and other bodily functions. It also causes physical changes like vision problems, extra fingers or toes (polydactyly), and kidney issues. BBS affects boys and girls equally.

BBS can sometimes be identified before birth, especially if there's a family history of the condition. During pregnancy, doctors may notice signs like extra fingers or toes or enlarged kidneys on an ultrasound. These clues can help families prepare early for their baby's care needs.

The condition affects about 1 in 100,000 people in parts of Europe and North America, but it's more common in certain populations. For example, it affects around 1 in 13,500 people in the Bedouin population of Kuwait and 1 in 17,500 in Newfoundland. A specific genetic change linked to BBS is also common in South Africa.

Children with BBS often feel hungry all the time because their brain doesn't send proper "full" signals after eating. This can lead to overeating and weight gain. Managing BBS usually involves working with a healthcare team to address these challenges through nutrition, physical activity, and regular medical care.

Hypothalamic Obesity

Hypothalamic Obesity (HO) is another rare disorder affecting Australian children. The condition is caused by damage to the hypothalamus, a small part of the brain that controls hunger, metabolism, and other body functions. When hunger in children is out of control, children eat excessively, and obesity can be the result. HO also affects energy regulation. Tumours and head injuries are the typical causes of Hypothalamic Obesity.

MC4R Pathway Deficiencies

Deficiencies along the MC4R (melanocortin 4 receptor) pathway can lead to rare genetic forms of obesity, which are often underdiagnosed. Many healthcare professionals may not be aware of these conditions, contributing to delays in diagnosis and treatment.

Children with MC4R pathway deficiencies often show two key symptoms: early-onset, severe obesity and an unusually strong, constant feeling of hunger (hyperphagia). They may also have other health issues like neurological differences, growth problems, hormonal imbalances, and a family history of significant weight differences among relatives.

The true prevalence of MC4R-related genetic obesity is unknown because it's rarely suspected, and without suspicion, genetic testing isn't commonly pursued. However, estimates suggest that these conditions could affect more people than currently recognised.

How these conditions can exacerbate typical obesity-related challenges

Obesity in children results in several physical and psychological challenges, and the above rare diseases only serve to exacerbate these challenges, which include:

1. The potential to develop Type 2 diabetes (though interestingly this is uncommon in PWS).
2. High cholesterol and high blood pressure, increasing the risk of heart disease.
3. Extra weight causes joint pain in the back, knees, and hips and sometimes scoliosis.
4. Breathing problems such as asthma and obstructive sleep apnea (OSA) are more common in these children with severe obesity.
5. Gastroesophageal reflux disease (GORD).
6. Obesity can affect a child's psychological health, and the child and family can be subject to weight stigmatisation.

Why Early Intervention is Critical

If your child has one of these rare diseases, then early intervention is critical to prevent weight gain and obesity. The risks of a delayed reaction include lifelong obesity issues, cardiovascular diseases, and psychological issues.

Seeking early specialist help and support and understanding from your primary care team is essential while documenting the often severe and rapid weight gain in the first two years of life is essential, though in children with PWS the increased appetite switch often does not occur until after 5 years of age.

However, with timely identification of a rare disease and tailored interventions to manage it, you will vastly improve the outlook for your child’s future. It’s important to enlist the help of multidisciplinary teams, including general paediatricians, specialists, dietitians and exercise physiologists, and if appropriate, early support from the National Disability Insurance Scheme (NDIS).

Some children can be helped from taking specific metabolic medications and there are ongoing trials of different new medicines that are promising and potentially helpful, if supervised by the child’s paediatrician and paediatric endocrinologist.