Jacobsen Syndrome

Chromosome 11, partial monosomy 11q is characterized by abnormally prenatal and postnatal growth retardation, mental retardation, psychomotor retardation, craniofacial anomalies, ocular abnormalities, malformations of the hands and/or feet, and congenital heart defects (e.g., ventricular septal defect).

11q-Deletion Syndrome; Partial 11q Monosomy Syndrome.

Approximately 1:100,000 live births.

Autosomal dominant. Parent may carry a complete but fragile 11q chromosome. Folate deficient chromosome breakage may occur in early development, leading to full Jacobsen phenotypes. The parent may not carry the syndrome despite autosomal dominant transmission. Chromosomal deletion leading to CCG repeat triplets and multiorgan involvement.

The exact cause of this chromosomal deletion and triplet expansion is unknown.

Based on clinical criteria and laboratory demonstration of the deletion on the short arm of chromosome 11 (locus 11q23-24).

Present at birth with dysmorphic signs including low-set dysmorphic ears; broad, short nose with anteverted nostrils; retrognathia; U-shaped upper lip; divergent strabismus; and hammertoes and bent fingers. These children have growth and developmental retardation. Jacobsen syndrome is associated with an isoimmune thrombocytopenia.

Because of the dysmorphism affecting the nose and mouth, carefully check the airway and whether difficult airway management should be anticipated. The presence of congenital heart defect must be eliminated. Check blood count for thrombocytopenia. Check for associated abnormalities, especially of the heart and lungs. An anesthesia consultation for elective surgical procedure should be obtained.

Use safe airway control strategy. Be prepared for difficult direct laryngoscopy and tracheal intubation. Maintain spontaneous ventilation until the trachea is intubated and lungs ventilated. A laryngeal mask should be available. Be prepared to use other means of airway management (e.g., fiberoptic, Bullard laryngoscope, retrograde intubation technique) to facilitate tracheal intubation. In most difficult cases, equipment for cricothyroidotomy should be available. Only then, if necessary, can a muscle relaxant be used. The anesthetic management also is dictated by the presence of congenital anomalies of the heart. Strict asepsis must be provided because of immune system defect.

No specific implications with this disorder.

Paris-Trousseau Syndrome: Hematologic disorder associating low platelet count and abnormal platelet function. The intriguing fact is that all known patients with Jacobsen Syndrome have Paris-Trousseau Syndrome (which seems to be a variant of Jacobsen Syndrome, with the same gene map locus).

Chromosome 11 Ring: Caused by a break of the long and short arms of chromosome 11. It is characterized by failure to thrive, psychomotor retardation, craniofacial anomalies (e.g., microbrachycephaly, short nose with a low, depressed nasal bridge, microretrognathism, low-set ears), ocular abnormalities, a short neck, pancytopenia, and congenital heart defects. The exact cause of chromosome 11 ring is not fully understood.

C Syndrome: Characterized by a “triangular-shaped” head with trigonocephaly resulting from severe craniosynostosis. Other clinical features include craniofacial anomalies, a short nose with a broad nasal bridge, epicanthus, cleft palate, and low-set, malformed ears. Joint subluxations or contractures have been observed with this condition. In some cases, congenital heart defects and mental retardation are present. It is thought to be inherited as an autosomal recessive trait.