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] A 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 the syndrome 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 make up alone.[5] Another study however with an individual of YSS 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 1050356. 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 1016313. 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 3213399. PMID 22077973.