AN OVERVIEW OF LESS KNOWN JACOBSEN SYNDROMEAN OVERVIEW OF LESS KNOWN JACOBSEN SYNDROME

Jacobsen syndrome is catastrophic in 1 out of every 5 cases, with children usually dying within the first 2 years of life due to heart complications. Jacobsen syndrome is a contiguous gene syndrome caused by partial deletion of the long arm of chromosome 11. The prevalence has been estimated at 1/100,000 births, with a female/male ratio 2:1. The most common clinical features include pre- and postnatal physical growth retardation, psychomotor retardation, and characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears). Abnormal platelet function, thrombocytopenia or pancytopenia are usually present at birth. Patients commonly have malformations of the heart, kidney, gastrointestinal tract, genitalia, central nervous system and skeleton. Ocular, hearing, immunological and hormonal problems may be also present. The deletion size ranges from 07 to 20 Mb, with the proximal breakpoint within or telomeric to subband 11q 23.3 and the deletion extending usually to the telomere. The deletion is de novo in 85% of reported cases, and in 15% of cases it results from an unbalanced segregation of a familial balanced translocation or from other chromosome rearrangements. Diagnosis is based on clinical findings (intellectual deficit, facial dysmorphic features and thrombocytopenia) and confirmed by cytogenetics analysis.