Most children eventually start speaking, but in cases with severe intellectual disability language use is highly restricted.They have distinctive facial features like:

Small head (microcephaly)
Pointed forehead (trigonocephaly)
Small ears which are low-set
Widely-spaced eyes (hypertelorism)
Droopy eyelids (ptosis)
Broad nasal bridge
Abnormally thin upper lips
Downturned corners of the mouth
Excess skin covering in the inner corner of eyes (epicanthal folds)Some children also experience behavioural problems like distractibility, hyperactivity, impaired communication and social skills, which qualifies them for a diagnosis of ASD and ADHD. Heart defects are very common in children with Jacobsen syndrome. 88.5% of people with the disorder have Paris-Trousseau syndrome, which is a bleeding disorder and causes a lifelong risk of abnormal bleeding and bruising due to dysfunction in the platelets. Other symptoms may include eye problems, ear and sinus infections, hearing problems, bone deformities, growth hormone deficiency, gastrointestinal problems, kidney malfunctions, etc. Cause
Jacobsen syndrome is caused by deletion of genetic material from the long arm of chromosome 11. The size of deletion may vary across patients, but the deletion always occurs at the end terminal of the q arm of chromosome 11. There are three ways in which the deletion could occur:
de novo deletion- this is a random event that occurred during the formation of the sperm or the egg or during the cell division in the embryonic stage, where genes from chromosome 11 get deleted.Imbalanced translocation- in this case, a parent with balanced translocation or other types of chromosomal rearrangement can pass on these genes to their children which further results in an imbalanced translocation.
A simple assessment of the symptoms can be done to diagnose the syndrome. A thorough physical examination could be carried out to assess the symptoms. Treatment
There has been no treatment discovered for Jacobsen syndrome to date, but the symptoms can be treated. 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. Any problems that are found can be treated then.Monthly CBT may help ease bleeding disorders. Consecutively, platelet transfusion and ddAVP can be carried out. Medication that interferes with platelet count should be avoided, and oral contraceptive therapy may be considered for women with heavy bleeding during menses.An evaluation by a neuropsychologist or a behaviour specialist like a psychiatrist or psychologist can be performed, including brain imaging like MRI or ERP. Later, as deemed appropriate, intervention programs can be carried through. Music therapy is very beneficial for language development. According to the age, vision and hearing tests can aid in fixing problems related cognition. For problems related to behaviour like ADHD, medication or therapy would be required but a combination of both is more effective. An ophthalmologist should be consulted to treat the eye defects. Play and interactive games encourage the child to speak. Habilitiation in children should begin at an early age. A habilitation team includes professionals with special expertise in how disability affects everyday life, health and development.