Trisomy Disorders

Trisomy 2

Posted on: October 30, 2008

chromosome 2 trisomy syndrome Synonyms 2 trisomy trisomy 2 Summary Presence of an additional (third) chromosome in an otherwise diploid chromosome complex with variable multiple congenital abnormalities consisting of craniofacial dysmorphism, genital malformation, hand and foot deformities, growth retardation, growth delay, congenital heart defects, and other anomalies.

Major Features

Head and neck: Microcephaly, midfacial hypoplasia, flat malar area, prominent occiput, pointed chin, and frontal bossing.

Ears: Posteriorly rotated ears, flat outer helices, and prominent anthelices.

Eyes: Hypertelorism, proptosis with contralateral ptosis, prominent inner canthal folds, epicanthus, and telecanthus.

Nose: Prominent beaked nose.

Mouth and oral structures: Highly arched palate, cleft lip and palate, and thin lips.

Thorax: Widely spaced nipples, pectus excavatum, and funnel chest.

Abdomen: Inguinal hernia and ascites.

Hand and foot: Overlapping 4th and 5th fingers, overlapping toes, broad halluces, rocker bottom feet, and radial deviation of the wrist. Dermatoglyphic findings consist mainly of simian creases.

Extremities: Hemimelia and radioulnar hypoplasia.

Spine: Scoliosis.

Muscles: Hypotonia.

Skin appendages: Central hair whorl.

Nervous system: Paucity of white matter, thincorpus callosum, hippocampal dysplasia, and abnormal sulcus in the frontal lobe.

 Cardiovascular system: Ventricular septal defect, overriding aorta, aortic valve prolapse, patent ductus arteriosus, and tricuspid regurgitation.

Respiratory system: Bronchopulmonary dysplasia.

Gastrointestinal system: Necrotizing enterocolitis and abnormal motility. Cholestasis and fibrosis.

Urogenital system: Ambiguous external genitalia, urethral meatus on the dorsum of the penis, hydronephrosis, and vesico-ureteral reflux.

Endocrine system: Hypothyroidism.

Growth and development: Growth, motor, and mental retardation.

 Heredity: All reported cases of trisomy 2 are mosaic.

Trisomy Two

Selected Bibliography

Casey J et al Prenatal diagnosis of trisomy 2 mosaicism confirmed in foreskin fibroblasts. Am J Hum Genet, 1990, 47:270

Cramer AE et al Tissue-specific trisomy 2 mosaicism in an infant with Pfeiffer syndrome-like features. Am J Hum Genet, 1993, 53:538

Harrison K et al Maternal uniparental disomy of chromosome 2 in a baby with 2 mosaicism in amniotic fluid culture. Am J Med Genet, 1995, 58:147-51 [MEDLINE]

Pappas JG et al Trisomy 2 mosaicism. Am J Hum Genet, 1995, 57:A286 Sago H et al True trisomy 2 mosaicism in amniocytes and newborn liver associated with multiple system abnormalities. Am J Med Genet, 1997, 72:343-6 [MEDLINE]

Shaffer LG et al Analysis of nine pregnancies with confirmed placental mosaicism for trisomy 2. Prenat Diag, 1996, 16:899-905

Webb AL et al Maternal uniparental disomy for chromosome 2 in association with confined placental mosaicism for trisomy 2 and severe intrauterine growth retardation. Prenat Diag, 1996, 16:959-62

Pub Med Links Page

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