Editing Prader–Willi syndrome (section)

== Diagnosis ==
It is traditionally characterized by hypotonia, short stature, hyperphagia, obesity, behavioral issues (specifically [[obsessive–compulsive disorder]]-like behaviors), small hands and feet, hypogonadism, and mild intellectual disability.<ref name="killeen-41" /> However, with early diagnosis and early treatment (such as with growth hormone therapy), the prognosis for persons with PWS is beginning to change. Like autism, PWS is a spectrum disorder and symptoms can range from mild to severe and may change throughout the person's lifetime. Various organ systems are affected.<ref>{{Cite web |date=2021-12-29 |title=What are the symptoms of Prader-Willi syndrome (PWS)? {{!}} NICHD - Eunice Kennedy Shriver National Institute of Child Health and Human Development |url=https://www.nichd.nih.gov/health/topics/prader-willi/conditioninfo/symptoms |access-date=2024-06-22 |website=www.nichd.nih.gov |language=en}}</ref>

Traditionally, PWS was diagnosed by clinical presentation. Currently, the syndrome is diagnosed through genetic testing; testing is recommended for newborns with pronounced hypotonia. Early diagnosis of PWS allows for early intervention and the early prescription of [[growth hormone]]. Daily recombinant growth hormone (GH) injections are indicated for children with PWS. GH supports linear growth and increased muscle mass, and may lessen food preoccupation and weight gain.<ref>{{cite web |last1=Driscoll |first1=Daniel |last2=Miller |first2=Jennifer |last3=Cassidy |first3=Suzanne |title=Prader-Willi Syndrome |url=https://www.ncbi.nlm.nih.gov/books/NBK1330/ |website=National Library of Medicine |publisher=University of Washington, Seattle |access-date=11 April 2025 |date=6 October 1998}}</ref>

The mainstay of diagnosis is [[genetic testing]], specifically DNA-based methylation testing to detect the absence of the paternally contributed PWS/AS region on chromosome 15q11.2-q13. Such testing detects over 99% of cases. Methylation-specific testing is important to confirm the diagnosis of PWS in all individuals, but especially those who are too young to manifest sufficient features to make the diagnosis on clinical grounds or in those individuals who have atypical findings.<ref>{{cite web |last1=Fermin Gutierrez |first1=Maria |last2=Daley |first2=Sharon |last3=Mendez |first3=Magda |title=Prader-Willi Syndrome |url=https://www.ncbi.nlm.nih.gov/books/NBK553161/ |website=National Library of Medicine |publisher=StatPearls Publishing |access-date=11 April 2025}}</ref>

PWS is often misdiagnosed due to its unfamiliarity in the medical community. Sometimes it is misdiagnosed as [[Down syndrome]],<ref name="Nordqvist">{{cite web|last=Nordqvist|first=Christian|title=What Is Prader-Willi Syndrome? What Causes Prader-Willi Syndrome?|url=http://www.medicalnewstoday.com/articles/182287.php|work=Medical News Today|publisher=MediLexicon International|access-date=December 4, 2012|date=March 15, 2010|url-status=live|archive-url=https://web.archive.org/web/20130116005513/http://www.medicalnewstoday.com/articles/182287.php|archive-date=January 16, 2013}}</ref>  simply because of the relative frequency of Down syndrome compared to PWS.<ref name="Nordqvist" />