Jacobsen syndrome (also known as the chromosome 11q deletion syndrome) is a rare chromosomal anomaly that results from deletion of the terminal region of chromosome 11. It results in intellectual disabilities, a distinctive facial appearance and a variety of physical problems including heart defects and bleeding diathesis.
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Epidemiology
The estimated incidence is at approximately 1 out of every 100,000 births. There may be greater female predilection.
Clinical spectrum
It can cause intellectual disabilities, a distinctive facial appearance, and a variety of physical problems, including:
- pre- and postnatal physical growth restriction: IUGR
- psychomotor retardation
- congenital cardiac anomalies
- characteristic facial dysmorphism
- skull deformities: trigonocephaly 5
- hypertelorism
- ptosis
- coloboma
- downslanting palpebral fissures
- epicanthal folds
- broad nasal bridge
- short nose
- v-shaped mouth
- small ears: microtia
- low set posteriorly rotated ears: low set ears
- abnormal platelet function: thrombocytopenia or pancytopenia are usually present at birth
Pathology
It results from a deletion of a terminal region of chromosome 11 that includes band 11q24.1.
The majority of cases are not familial and result from a spontaneous mutation occurring in a single parental gamete. However, some instances of familial disease resulting from local chromosome fragility or an unbalanced translocation have been described.
History and etymology
It is named after Petra Jacobsen, the Danish physician who first described the syndrome in 1973 1.