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Trisomy 9


Trisomy 9

Trisomy 9
Classification and external resources
ICD-10 Q92
ICD-9-CM 758
DiseasesDB 32657
MeSH D014314

Full Trisomy 9 is a lethal chromosomal disorder caused by having three copies (trisomy) of chromosome number 9. It can be a viable condition if trisomy affects only part of the cells of the body mosaicism or in cases of partial trisomy (Trisomy 9p) in which cells have a normal set of 2 entire chromosomes 9 plus part of a third copy, usually of the short arm of the chromosome (arm p).


  • Characteristics 1
  • Detection 2
  • References 3
  • External links 4


Symptoms vary, but usually result in dysmorphisms in the skull, nervous system, and developmental delay. Dysmorphisms in the heart, kidneys, and musculoskeletal system may also occur. An infant with complete trisomy 9 surviving 20 days after birth showed clinical features including a small face, wide fontanelle, prominent occiput, micrognathia, low set ears, upslanting palpebral fissures, high-arched palate, short sternum, overlapping fingers, limited hip abduction, rocker bottom feet, heart murmurs and also a webbed neck.[1]

Trisomy 9p is one of the most frequent autosomal anomalies compatible with long survival rate. A study of 5 cases showed an association with Coffin–Siris syndrome, as well as a wide gap between the 1st and 2nd toes in all five, while three had brain malformations including dilated ventricles with hypogenesis of the corpus callosum and Dandy-Walker malformation.[2]


Trisomy 9 can be detected prenatally with chorionic villus sampling and cordocentesis, and can be suggested by obstetric ultrasonography.

Because trisomy 9 may appear with mosaicism, it is suggested that doctors take samples from multiple tissues when karyotyping for diagnosis.[3]


  1. ^ Kannan, T. P.; Hemlatha, S.; Ankathil, R.; Zilfalil, B. A. (2009). "Clinical manifestations in trisomy 9". The Indian Journal of Pediatrics 76 (7): 745–6.  
  2. ^ Temtamy, SA; Kamel, AK; Ismail, S; Helmy, NA; Aglan, MS; El Gammal, M; El Ruby, M; Mohamed, AM (2007). "Phenotypic and cytogenetic spectrum of 9p trisomy". Genetic counseling 18 (1): 29–48.  
  3. ^ Stipoljev, F.; Kos, M.; Kos, M.; Miskovi, B.; Matijevic, R.; Hafner, T.; Kurjak, A. (2003). "Antenatal detection of mosaic trisomy 9 by ultrasound: A case report and literature review". The Journal of Maternal-Fetal & Neonatal Medicine 14 (1): 65–9.  

External links

  • NORD - National Organization for Rare Disorders, Inc. Chromosome 9, Trisomy 9p (Multiple Variants)
  • NORD - National Organization for Rare Disorders, Inc. Chromosome 9, Trisomy Mosaic
  • Maggi Blair - Trisomy 9 Mosaic Syndrome
  • TRISOMY 9p / Mosaic Trisomy 9 / Trisomy 9 duplication / chromosome 9 / Survey on Trisomy 9*[]
  • Trisomy 9 Mosaicism Information Guide by Unique Support Group
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