Noonan syndrome differential diagnosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Serge Korjian
Overview
Noonan syndrome can be considered in any patient with congenital cardiac anomalies although 2 important syndromes can resemble the Noonan phenotype particularly LEOPARD syndrome and Turner syndrome in girls.
Differential Diagnosis
LEOPARD Syndrome
LEOPARD syndrome, also known as multiple lentigines syndrome, is a rare congenital condition characterized by skin, facial and cardiac anomalies. LEOPARD is an acronym that summarizes the most important features of this disease which includes Lentigines, ECG findings (conduction abnormalities), Ocular problems (hypertelorism), Pulmonic stenosis, Abnormal genitalia, growth Retardation, and Deafness.[1] Phenotypically and genotypically, LEOPARD syndrome closely resembles Noonan syndrome although around 200 cases have only been reported worldwide. The disorder also involves mutations in the PTPN11 gene responsible for the NSH-2 domain on SHP-2. Several common loci of missense mutations are shared between these 2 syndromes, and genetic analysis alone can sometimes be hard to differentiate the two. Clinically, LS is a combination of neurofibromatosis type 1 and Noonan syndrome. The lentigines are important to make the diagnosis, although some do not appear before 4 to 5 years of age. Other signs more prominent in LS compared to Noonan are the very high prevalence of hypertrophic cardiomyopathy and deafness.[2]
Turner Syndrome
Turner syndrome is a congenital disorder that occurs in 1 of every 2000 to 5000 live female births. It does not affect male patients as it is characterized by an XO karyotype. Clinically, Turner syndrome can have variable phenotypes with features usually including congenital lymphedema, short stature, congentical cardiac abnormalities, and gonadal dysgenesis.[3] Although Turner syndrome has been genetically and clinically delineated and can be relatively easily differentiated from Noonan's syndrome, initially, Noonan's was considered a form of Turner syndrome that can affect males. In 1968, Dr. Jacqueline Noonan published a paper entitled "Hypertelorism With Turner Phenotype: A New Syndrome With Associated Congenital Heart Disease" describing the syndrome as "the male Turner syndrome".[4] In females with any difficulty in differentiating the syndromes clinically due to the variable expression, karyotype and genetic analysis are helpful.
References
- ↑ Gorlin RJ, Anderson RC, Moller JH (1971). "The leopard (multiple lentigines) syndrome revisited". Laryngoscope. 81 (10): 1674–81. doi:10.1288/00005537-197110000-00015. PMID 4398858.
- ↑ Sarkozy A, Digilio MC, Dallapiccola B (2008). "Leopard syndrome". Orphanet J Rare Dis. 3: 13. doi:10.1186/1750-1172-3-13. PMC 2467408. PMID 18505544.
- ↑ Sybert VP, McCauley E (2004). "Turner's syndrome". N Engl J Med. 351 (12): 1227–38. doi:10.1056/NEJMra030360. PMID 15371580.
- ↑ Noonan JA (1968). "Hypertelorism with Turner phenotype. A new syndrome with associated congenital heart disease". Am J Dis Child. 116 (4): 373–80. PMID 4386970.
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