People with Jacobsen syndrome have serious intellectual disabilities, dysmorphic features, delayed development and a variety of physical problems including heart defects.

[3] 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.

[4] Almost all children with Jacobsen syndrome have intellectual disabilities, which range from mild to moderate depending upon the number of the deletions of genes from the chromosome.

Most children eventually start speaking, but in cases with severe intellectual disability language use is highly restricted.

[6] They have distinctive facial features like: Some children also experience behavioural problems like distractibility, hyperactivity, impaired communication and social skills, which qualifies them for a diagnosis of ASD and ADHD.

56% of children with Jacobsen syndrome have congenital heart problems; to keep them in check, a baseline evaluation can be made by a paediatric cardiologist by carrying out an electrocardiogram or echocardiogram.

Medication that interferes with platelet count should be avoided, and oral contraceptive therapy may be considered for women with heavy bleeding during menses.

[citation needed] An evaluation by a neuropsychologist or a behaviour specialist like a psychiatrist or psychologist can be performed, including brain imaging like MRI or ERP.

A habilitation team includes professionals with special expertise in how disability affects everyday life, health and development.