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Prader-Willi syndrome

An evidence-led atlas of chromosome 15 imprinting, infant hypotonia and feeding difficulty, later hyperphagia, and lifelong multidisciplinary care.

Prader-Willi syndrome · PWS

MONDO:0008300Public QA completeSource-bound · 4

Disease at a glance

Start with the essentials, then explore the patient and research views.

Public revision · 48d4c1bc49e7

Disease class
Prader-Willi syndrome is a genetic disorder affecting neurodevelopment, growth, appetite, and endocrine function.
Core mechanism
Loss of paternal gene expression at 15q11.2-q13 is central and can result from deletion, maternal uniparental disomy, or an imprinting defect.
Genes or cause
Most cases occur without family history, but recurrence risk varies by molecular cause, supporting genetic counseling.
Typical features
Severe hypotonia, weak cry, feeding difficulty, and poor growth are common in infancy.
Variability
Hyperphagia and food seeking emerge in childhood and create major obesity risk without management.
Diagnosis
Diagnosis identifies maternal-only imprinting by DNA methylation analysis and uses additional testing to define the molecular cause.
Management
A routine karyotype or standard exome test alone cannot detect every molecular mechanism.
Treatment and research
Safe nutrition in infancy and later structured food access and energy management are age-specific priorities.
Reading evidence
Growth hormone can be used after evaluation and with monitoring to improve growth, body composition, and function.
Key caution
Drug treatment for hyperphagia requires specialist review of approved indication, age, benefits, and adverse effects.

For patients and families

A structured guide for understanding the disease and preparing for clinical conversations.

At a glance

Prader-Willi syndrome is a genetic disorder affecting neurodevelopment, growth, appetite, and endocrine function.

Severe hypotonia, weak cry, feeding difficulty, and poor growth are common in infancy.

How the disease works

Loss of paternal gene expression at 15q11.2-q13 is central and can result from deletion, maternal uniparental disomy, or an imprinting defect.

Most cases occur without family history, but recurrence risk varies by molecular cause, supporting genetic counseling.

Why experiences vary

Hyperphagia and food seeking emerge in childhood and create major obesity risk without management.

Diagnosis and management

Diagnosis identifies maternal-only imprinting by DNA methylation analysis and uses additional testing to define the molecular cause.

Treatment status

A routine karyotype or standard exome test alone cannot detect every molecular mechanism.

Safe nutrition in infancy and later structured food access and energy management are age-specific priorities.

Reading clinical trials

Multidisciplinary care addresses development, behavior, mental health, skin picking, and family support.

Topics for a clinical visit

Clinical discussion should cover molecular subtype, nutritional phase, respiratory and endocrine risks, food-safety planning, and family support.

Medical notice

This material is for disease education and is not a personal diagnosis or treatment instruction.

Evidence and sources

A trial registry status does not establish efficacy or regulatory approval.