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Chromosome 18, tetrasomy 18p

MedGen UID:
167079
Concept ID:
C0795868
Disease or Syndrome
Synonyms: Isochromosome 18p; ISOCHROMOSOME 18p SYNDROME; Tetrasomy 18p; Tetrasomy, Short Arm of Chromosome 18
SNOMED CT: Tetrasomy 18p (698849002); 18p tetrasomy (698849002); 18p isochromosome (698849002)
 
Cytogenetic location: 18p
OMIM®: 614290
Orphanet: ORPHA3307

Definition

Tetrasomy 18p is a chromosomal condition that affects many parts of the body. This condition usually causes feeding difficulties in infancy, delayed development, intellectual disability that is often mild to moderate but can be severe, changes in muscle tone, distinctive facial features, and other birth defects. However, the signs and symptoms vary among affected individuals.Babies with tetrasomy 18p often have trouble feeding and may vomit frequently, which makes it difficult for them to gain weight. Some affected infants also have breathing problems and jaundice, which is a yellowing of the skin and the whites of the eyes.Changes in muscle tone are commonly seen with tetrasomy 18p. Some affected children have weak muscle tone (hypotonia), while others have increased muscle tone (hypertonia) and stiffness (spasticity). These changes contribute to delayed development of motor skills, including sitting, crawling, and walking.Tetrasomy 18p is associated with a distinctive facial appearance that can include unusually shaped and low-set ears, a small mouth, a flat area between the upper lip and the nose (philtrum), and a thin upper lip. Many affected individuals also have a high, arched roof of the mouth (palate), and a few have had a split in the roof of the mouth (cleft palate).Additional features of tetrasomy 18p can include seizures, vision problems, recurrent ear infections, mild to moderate hearing loss, constipation and other gastrointestinal problems, abnormal curvature of the spine (scoliosis or kyphosis), a shortage of growth hormone, and birth defects affecting the heart and other organs. Males with tetrasomy 18p may be born with undescended testes (cryptorchidism) or the opening of the urethra on the underside of the penis (hypospadias). Psychiatric conditions, such as attention deficit hyperactivity disorder (ADHD) and anxiety, as well as social and behavioral challenges have also been reported in some people with tetrasomy 18p.
[from GHR]

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVChromosome 18, tetrasomy 18p
Follow this link to review classifications for Chromosome 18, tetrasomy 18p in Orphanet.

Recent clinical studies

Etiology

Lildballe DL, Vogel I, Lund IC, Stornes I, Jørgensen MW, Vestergaard EM
Prenat Diagn 2016 Dec;36(12):1112-1114. Epub 2016 Nov 10 doi: 10.1002/pd.4943. PMID: 27743407
O'Donnell L, Soileau BT, Sebold C, Gelfond J, Hale DE, Cody JD
Am J Med Genet A 2015 Jul;167(7):1474-82. Epub 2015 Apr 21 doi: 10.1002/ajmg.a.37036. PMID: 25900901

Diagnosis

Lildballe DL, Vogel I, Lund IC, Stornes I, Jørgensen MW, Vestergaard EM
Prenat Diagn 2016 Dec;36(12):1112-1114. Epub 2016 Nov 10 doi: 10.1002/pd.4943. PMID: 27743407
White WA, Schatz MP, Sebold C, Hale DE, Cody J
J AAPOS 2011 Jun;15(3):268-71. Epub 2011 Jun 12 doi: 10.1016/j.jaapos.2011.02.011. PMID: 21665505

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