Jacobsen syndrome

What is Jacobsen syndrome?

Jacobsen syndrome is a rare genetic disorder caused by deletions in the long arm of chromosome 11 (11q). This is why it is sometimes called partial monosomy 11q. The number of genes deleted from the chromosome will determine how severe the disorder is. Most cases of Jacobsen syndrome are not inherited. Only between 5 and 10 percent of cases occur when a child inherits the disorder from an unaffected parent. These parents have genetic material that is rearranged but still present in chromosome 11. This is called balanced translocation. If Jacobsen syndrome is inherited, parents have a slightly higher risk of having another child with the condition.

Signs and symptoms

Jacobsen syndrome is characterized by craniofacial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, a broad nasal bridge, short nose, V-shaped mouth, and small, low-set and posteriorly rotated ears), craniosynostosis, eye abnormalities, congenital heart disease, intellectual disability, behavioral problems including ADHD and autism, seizures, Paris-Trousseau bleeding disorder, structural kidney defects and other urogenital anomalies including undescended testes in males, chronic constipation, pyloric stenosis, and immunodeficiency.

Children with Jacobsen syndrome

Girls are twice as likely to develop this syndrome than boys. There is no cure for Jacobsen syndrome, so treatment will focus on improving the child’s overall health. Treatment will focus on addressing health complications that arise and helping the child reach developmental milestones. The life expectancy of children with this condition is unknown, but individuals can and have lived into adulthood. Many adults with Jacobsen syndrome can live happy, fulfilling, and semi-independent lives.

Diagnosis of Jacobsen syndrome

Genetic testing is necessary to confirm a Jacobsen syndrome diagnosis, which can be done prenatally. So far, diagnosis has been based on clinical findings and confirmed by array comparative genomic hybridization, and/or FISH.

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