NeurometPlus

Incidence

Transmitted as autosomal dominant trait. Isolated cases. 75% of affected individuals are female. The estimated incidence of Jacobsen syndrome is 1 in 100,000 newborns. More than 200 affected individuals have been reported, with a female/male ratio of 2:1. Update 2017/ MGJM

Clinical Characteristics

The Jacobsen syndrome is a clinically characteristic disorder due to deletion of the terminal band 11q23. This band is known to harbor a heritable folate-sensitive fragile site. The features of the syndrome are growth retardation, psychomotor retardation, trigonocephaly, divergent intermittent strabismus, epicanthus, telecanthus, broad nasal bridge, short nose with anteverted nostrils, carp-shaped upper lip, retrognathia, low-set dysmorphic ears, bilateral camptodactyly, hammer toes, and isoimmune thrombocytopenia. In summary, deletion of the long arm of chromosome 11 presents with retarded growth and psychomotor development, trigonocephaly, strabismus, short and broad nose with anteverted nostrils, epicanthus, telecanthus, malformed ears, \"carp mouth\", camptodactyly, and thrombocytopenia. More than 90 percent of people with Jacobsen syndrome have a bleeding disorder called Paris-Trousseau syndrome. This condition causes a lifelong risk of abnormal bleeding and easy bruising. Paris-Trousseau syndrome is a disorder of platelets, which are blood cell fragments that are necessary for blood clotting. Other features of Jacobsen syndrome can include heart defects, feeding difficulties in infancy, short stature, frequent ear and sinus infections, and skeletal abnormalities. The disorder can also affect the digestive system, kidneys, and genitalia. The life expectancy of people with Jacobsen syndrome is unknown, although affected individuals have lived into adulthood.
(Update September 2017. MGJM)

Precipitants

None

Provocation Tests

None

Diagnostic Procedures

Diagnosis is based on clinical findings and confirmed by cytogenetic analysis.
Karyotype. Deletion of the long arm of chromosome 11.