Diagnosing ROHHAD: Ruling Out Other Conditions

Because ROHHAD is a “clinical diagnosis,” meaning there is no single blood or genetic test to confirm it, doctors must work backward to ensure your child’s symptoms aren’t caused by more common or better-understood conditions ^[1][2]. This process is called differential diagnosis.

The “ROHHAD-like” appearance—rapid weight gain combined with breathing or hormonal issues—overlaps with several other rare disorders. To give your child the correct label, your medical team must systematically “rule out” these mimics, which may also include evaluating for structural hypothalamic disease or medication effects.

Prader-Willi Syndrome (PWS)

Prader-Willi Syndrome is perhaps the most well-known genetic condition that causes childhood obesity and hormonal changes. However, the “story” of how the weight gain starts is usually very different from ROHHAD ^[3].

• The Clinical Difference: Children with PWS typically have significant challenges from birth, including hypotonia (low muscle tone or “floppiness”) and a weak “suck,” which often leads to poor feeding and slow weight gain in infancy ^[3][4]. In contrast, children with ROHHAD are usually healthy, energetic, and meet all their milestones during their first year of life ^[5].
• The Test: Doctors use a specialized genetic test called 15q11-q13 DNA methylation analysis ^[4]. This test is highly sensitive for PWS. If this test is negative, PWS is effectively ruled out ^[4].

Congenital Central Hypoventilation Syndrome (CCHS)

CCHS shares the breathing difficulties seen in ROHHAD—specifically hypoventilation, where the brain “forgets” to tell the lungs to breathe deeply enough, especially during sleep ^[5][6].

• The Clinical Difference: The timing is often a clue. CCHS most commonly appears in the neonatal period (the first few days or weeks of life), though it can present later in childhood or be unmasked by an infection or anesthesia ^[5]. These babies struggle to breathe from birth but do not typically experience the sudden, massive weight gain that defines ROHHAD ^[7].
• The Test: CCHS is caused by mutations in the PHOX2B gene ^[8]. A blood test for this specific gene is required, which should use an appropriate assay for polyalanine expansions and other variants. A negative PHOX2B test makes CCHS much less likely, but it does not by itself confirm ROHHAD or absolutely exclude CCHS, as rare variants or mosaicism must be considered ^[9].

Cushing’s Syndrome

Cushing’s syndrome occurs when the body has too much of the hormone cortisol. Like ROHHAD, it causes rapid weight gain, particularly in the face and torso ^[10].

• The Clinical Difference: While both cause weight gain, Cushing’s usually causes a child’s height growth to slow down or stop entirely (growth suppression), whereas children with ROHHAD may continue to grow in height at a normal rate initially ^[11]. Cushing’s may also delay puberty and cause distinct purple stretch marks (striae) and high blood pressure ^[11][12].
• The Test: Since cortisol levels fluctuate, doctors usually need more than one test to evaluate this ^[13]. These may include:
  • 24-hour urinary free cortisol: A collection of urine over a full day.
  • Late-night salivary cortisol: A simple swab of the mouth before bed.
  • Dexamethasone suppression test: A medication-and-follow-up test where a dose of dexamethasone is taken and cortisol levels are checked later to see how the body responds ^[11][14].

Summary of Diagnostic Testing

To reach a ROHHAD diagnosis, your child’s records will likely need to show results for the following:

By process of elimination, when these conditions are ruled out and the child shows the “ROHHAD sequence”—starting with rapid weight gain and followed by breathing or autonomic issues—the clinical diagnosis of ROHHAD is made ^[15][5].