Jacobsen syndrome

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.

Epidemiology

The estimtated 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 retardation - IUGR
• psychomotor retardation
• congenital cardiac defects
• 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.

Etymology

It is named after Petra Jacobsen : Danish physician who first described the syndrome in 1973 ¹