Complete Trisomy 8 occurs in 0.8% of spontaneous pregnancy losses. Mosaic Trisomy 8 is characterized by severe mental retardation, craniofacial dysmorphism, skeletal anomalies, reduced joint mobility, complex congenital heart defect, and kidney malformations.
Trisomy 8: This girl with facial dysmorphism (high forehead, hypoplastic mandible) and low-set ears was diagnosed with a Trisomy 8 mosaicism.
Trisomy C; Trisomy 8s; Warkany Syndrome.
Very rare, 1:25,000 to 1:50,000.
Mosaicism is less common than what is often referred to as “full” trisomy. A mosaic exists when a person presents with trisomic cells in their body, but in the presence of normal chromosomic cells. The genetic error occurs during the division of cells after fertilization. Trisomy 8 is rarely observed at birth.
Clinically evocated; patients with trisomy 8 mosaicism present with moderate mental retardation, multiple skeletal anomalies, urogenital malformations, congenital heart defects, deep palmar and plantar furrows, distinct facial dysmorphism, and occasional agenesis of the corpus callosum.
Clinical features involve head and face (simian crease seizures; expressionless facies; micrognathia; prominent forehead; large dysplastic ears; microphthalmia; strabismus; hypertelorism; corneal opacity; cataract, heterochromia; everted lips; highly arched or cleft palate and stretched) and skeleton (camptodactyly 2nd to 5th fingers and toes, short neck; thin, elongated trunk; pectus carinatum; camptodactyly; clinodactyly; short metacarpal and metatarsal bones; absent or dysplastic patellae; multiple joint contractures; coxa valga; abnormal diaphyses and epiphyses of radial, femoral, and humeral bone; kyphoscoliosis, hemivertebrae; fusion of vertebrae; spina bifida; broad dorsal ribs). Abdominal and pelvic organs (hydronephrosis, ureteral reflux, cryptorchidism, malrotation or absence of gallbladder, jejunal duplication, gastric sarcoma) and thoracic organs (cardiac septal defects and great vessel anomalies) can present malformations. Systemic manifestation can present as Behçet Syndrome (recurrent oral and genital ulcers, eye lesions and skin lesions. Deep palmar and plantar furrows are frequent.
Precautions before anesthesia
Evaluate cardiac function (clinical, echocardiography, ECG) and renal function (echography, urea, creatinine, electrolytes).
Careful intraoperative positioning should be done (vertebral anomalies, joint contractures). Direct laryngoscopy and tracheal intubation can be difficult because of short neck and microretrognathia. Maintain spontaneous respiration until tracheal intubation is secured. The availability of a laryngeal mask airway and fiberoptic equipment is recommended. Venous access can be difficult because of limb anomalies. Perimedullar anesthesia is often contraindicated or difficult because of vertebral and spine anomalies.
Consider anesthetic drug interaction with antiepileptic medications. Endocarditis prophylactic as indicated in case of cardiac defect.
Other conditions to be considered