Trisomy 4p

At a glance

A rare chromosomal disorder in which all or a portion of the short arm (p) appears three times rather than twice in cells of the body. It is clinically characterized by breathing difficulties, craniofacial anomalies, hands and feet abnormalities, and congenital heart defects. Other clinical features include genital anomalies in affected males, skeletal defects, and severe mental retardation.

Synonyms

Chromosome 4, Partial Trisomy; Duplication 4p Syndrome.

Genetic inheritance

Duplication of the short arm of the fourth chromosome (dup(4)) leading to the appearance of three p arm (trisomy).

Clinical aspects

Head and neck: microcephaly, square face and flat forehead, prominent supraorbital ridges, short neck. Ears: enlarged ears, thickened helix and antihelix. Eyes: uveal coloboma, microphthalmia, down-slanting palpebral fissures. Mouth and nose: cleft lip and palate, macroglossia, pointed mandible. Cardiac defects: congenital heart defects are often associated. Respiratory system: absent or additional ribs, recurrent pulmonary aspiration leading to severe respiratory problems, broad chest with aging. Central nervous system: mental retardation, agenesis of the corpus callosum, severe seizures. Neuromuscular: present with hypertonic responses in the infancy period, but becoming severely hypotonic later. Other clinical features: clinodactyly of the fifth finger, camptodactyly, hypoplastic nails, preaxial polydactyly, congenital dislocated hips, syndactyly of the second and third toe, joint contractures, vertebral anomalies such as spinal hemivertebrae, hypospadias, micropenis, cryptorchidism, and obesity accompanied with redundant skin.

Precautions before anesthesia

Evaluate cardiac function (clinical, echocardiography, ECG) and assess respiratory function (because of recurrent pulmonary aspiration).

Anesthetic considerations

In presence of severe mental retardation, behavioral problems might affect considerably the preoperative period and anesthesia induction: premedication might be indicated, but the potential for a breathing problem may be a limitation. Careful intraoperative positioning should be done (vertebral anomalies, joint contractures and stiffness). Face-mask ventilation may be difficult and achieved using a two person-technique. Direct laryngoscopy and tracheal intubation can be difficult because of short neck and the presence of micrognathia and macroglossia. Predicted tracheal tube size may be too large. It is recommended to maintain spontaneous respiration until tracheal intubation is achieved and lung ventilation is confirmed. A laryngeal mask airway must be available. Venous access can be difficult because of the presence of puffy hands (redundant skin). Perimedullar anesthesia is often contraindicated or difficult because of vertebral and spine anomalies.

Pharmacological implications

Consider anesthetic drugs interactions with antiepileptic medications. The use of an intravenous antiepileptic relay must be considered intraoperatively. The chronic use of antiepileptic medications might affect the metabolism of the anesthetic agents. Prophylactic antibiotics should be as indicated in cases of cardiac defects. Avoid anesthetic drugs with marked cardiovascular effects.

Other condition to be considered

• Trisomy 10p: Less than ...