![]() Abstract: Barber Say syndrome (BSS) is a rare ectodermal dysplasia with neonatal onset characterized by congenital generalized hypertrichosis, atrophic skin, ectropion and macrostomia.Two further cases of Ohdo syndrome delineate the phenotypicvariability of the condition. White SM, Adès LC, Amor D, Liebelt J, Bankier A, Baker E, Wilson M,Savarirayan R.Verloes A, Bremond-Gignac D, Isidor B, David A, Baumann C, Leroy MA, StevensR, Gillerot Y, Héron D, Héron B, Benzacken B, Lacombe D, Brunner H, Bitoun P.Blepharophimosis-mental retardation (BMR) syndromes: A proposed clinicalclassification of the so-called Ohdo syndrome, and delineation of two new BMRsyndromes, one X-linked and one autosomal recessive.Young-Simpson syndrome: further delineation of a distinct syndrome withcongenital hypothyroidism, congenital heart defects, facial dysmorphism, andmental retardation. Masuno M, Imaizumi K, Okada T, Adachi M, Nishimura G, Ishii T, Tachibana K,Kuroki Y.Seattle (WA): University of Washington,Seattle 1993-2020. In: Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, AmemiyaA, editors. A clinical and genetic study of theSay/Barber/Biesecker/Young-Simpson type of Ohdo syndrome. Day R, Beckett B, Donnai D, Fryer A, Heidenblad M, Howard P, Kerr B, MansourS, Maye U, McKee S, Mohammed S, Sweeney E, Tassabehji M, de Vries BB,Clayton-Smith J.Whole-exome-sequencing identifies mutations in histoneacetyltransferase gene KAT6B in individuals with the Say-Barber-Biesecker variantof Ohdo syndrome. Clayton-Smith J, O'Sullivan J, Daly S, Bhaskar S, Day R, Anderson B, Voss AK, Thomas T, Biesecker LG, Smith P, Fryer A, Chandler KE, Kerr B, Tassabehji M,Lynch SA, Krajewska-Walasek M, McKee S, Smith J, Sweeney E, Mansour S, MohammedS, Donnai D, Black G.The KAT6B-related disorders genitopatellar syndrome and Ohdo/SBBYS syndrome havedistinct clinical features reflecting distinct molecular mechanisms. Campeau PM, Lu JT, Dawson BC, Fokkema IF, Robertson SP, Gibbs RA, Lee BH.However, it is unclear how these changes lead to the specific features of the condition. Studies suggest that the resulting shortage of this enzyme impairs the regulation of various genes during early development. The mutations that cause the SBBYS variant of Ohdo syndrome likely prevent the production of functional histone acetyltransferase from one copy of the KAT6B gene in each cell. It appears to regulate genes that are important for early development, including development of the skeleton and nervous system. Little is known about the function of the histone acetyltransferase produced from the KAT6B gene. By adding a small molecule called an acetyl group to histones, histone acetyltransferases control the activity of certain genes. These enzymes modify histones, which are structural proteins that attach (bind) to DNA and give chromosomes their shape. ![]() This gene provides instructions for making a type of enzyme called a histone acetyltransferase. The SBBYS variant of Ohdo syndrome is caused by mutations in the KAT6B gene. The SBBYS variant of Ohdo syndrome can also be associated with heart defects and dental problems. About one-third of affected individuals are born with an opening in the roof of the mouth called a cleft palate. Additionally, affected individuals may have distinctive facial features such as prominent cheeks, a broad nasal bridge or a nose with a rounded tip, a narrowing of the eye opening (blepharophimosis), droopy eyelids (ptosis), and abnormalities of the tear (lacrimal) glands. The SBBYS variant of Ohdo syndrome is characterized by a mask-like, non-expressive face. Many affected infants have weak muscle tone (hypotonia) that leads to breathing and feeding difficulties. The SBBYS variant of Ohdo syndrome is also associated with delayed development and intellectual disability, which are often severe. Many people with this condition have long thumbs and first (big) toes. Although joints in the lower body are stiff, joints in the arms and upper body may be unusually loose (lax). Affected individuals also have joint stiffness involving the hips, knees, and ankles that can impair movement. Missing or underdeveloped patellae is the most common skeletal abnormality associated with the SBBYS variant of Ohdo syndrome. Females with this condition have normal genitalia. Males with the SBBYS variant of Ohdo syndrome typically have undescended testes (cryptorchidism).
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