Young–Simpson syndrome

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Young–Simpson syndrome
Classification and external resources
OMIM 603736

Young–Simpson syndrome (YSS) is a rare congenital disorder with symptoms including hypothyroidism, heart defects, facial dysmorphism, cryptorchidism in males, hypotonia, mental retardation and postnatal growth retardation.[1][2]

Other symptoms include transient hypothyroidism, macular degeneration and torticollis.[3] The condition was discovered in 1987 and the name arose from the individuals who first reported the syndrome.[4][5] An individual with YSS has been identified with having symptoms to a similar syndrome known as Ohdo Blepharophimosis syndrome, showing that it is quite difficult to diagnose the correct condition based on the symptoms present.[6] Some doctors therefore consider these syndromes to be the same.[7]

The mode of inheritance has had mixed findings based on studies undertaken.[5][8] One study showed that the parents of an individual with YSS are unrelated and phenotypically normal, indicating a sporadic mutation, thus making it difficult to base the cause of the condition on genetic makeup alone.[5] However, another study was done of an individual with YSS who had first cousins as parents, giving the possibility of autosomal recessive inheritance.[8]


In 2011, it was demonstrated that de novo mutations in the gene KAT6B caused YSS.[9]


  1. ^ Masuno M, Imaizumi K, Okada T, et al. (May 1999). "Young-Simpson syndrome: further delineation of a distinct syndrome with congenital hypothyroidism, congenital heart defects, facial dysmorphism, and mental retardation". Am J Med Genet. 84 (1): 8–11. doi:10.1002/(SICI)1096-8628(19990507)84:1<8::AID-AJMG2>3.0.CO;2-2. PMID 10213038. 
  2. ^ Young Simpson syndrome at NIH's Office of Rare Diseases
  3. ^ Kondoh T, Kinoshita E, Moriuchi H, Niikawa N, Matsumoto T, Masuno M (January 2000). "Young-Simpson syndrome comprising transient hypothyroidism, normal growth, macular degeneration and torticolis". Am J Med Genet. 90 (1): 85–6. doi:10.1002/(SICI)1096-8628(20000103)90:1<85::AID-AJMG17>3.0.CO;2-R. PMID 10602125. 
  4. ^ Young ID, Simpson K (November 1987). "Unknown syndrome: abnormal facies, congenital heart defects, hypothyroidism, and severe retardation". J Med Genet. 24 (11): 715–6. doi:10.1136/jmg.24.11.715. PMC 1050356Freely accessible. PMID 3430551. 
  5. ^ a b c Nakamura T, Noma S (August 1997). "A Japanese boy with Young-Simpson syndrome". Acta Paediatr Jpn. 39 (4): 472–4. doi:10.1111/j.1442-200x.1997.tb03621.x. PMID 9316295. 
  6. ^ Marques-de-faria AP, Maciel-Guerra AT, Júnior GG, Baptista MT (July 2000). "A boy with mental retardation, blepharophimosis and hypothyroidism: a diagnostic dilemma between Young-Simpson and Ohdo syndrome". Clin Dysmorphol. 9 (3): 199–204. doi:10.1097/00019605-200009030-00009. PMID 10955481. 
  7. ^ OHDO SYNDROME: Contact a Family - for families with disabled children: information on rare syndromes and disorders
  8. ^ a b Bonthron DT, Barlow KM, Burt AM, Barr DG (March 1993). "Parental consanguinity in the blepharophimosis, heart defect, hypothyroidism, mental retardation syndrome (Young-Simpson syndrome)". J Med Genet. 30 (3): 255–6. doi:10.1136/jmg.30.3.255. PMC 1016313Freely accessible. PMID 8474111. 
  9. ^ Clayton-Smith, Jill; O'Sullivan James; Daly Sarah; Bhaskar Sanjeev; Day Ruth; Anderson Beverley; Voss Anne K; Thomas Tim; Biesecker Leslie G; Smith Philip; Fryer Alan; Chandler Kate E; Kerr Bronwyn; Tassabehji May; Lynch Sally-Ann; Krajewska-Walasek Malgorzata; McKee Shane; Smith Janine; Sweeney Elizabeth; Mansour Sahar; Mohammed Shehla; Donnai Dian; Black Graeme (November 2011). "Whole-Exome-Sequencing Identifies Mutations in Histone Acetyltransferase Gene KAT6B in Individuals with the Say-Barber-Biesecker Variant of Ohdo Syndrome". Am. J. Hum. Genet. United States. 89 (5): 675–81. doi:10.1016/j.ajhg.2011.10.008. PMC 3213399Freely accessible. PMID 22077973.