Jacobsen Syndrome

Original Editor - Rania Nasr Top Contributors - Rania Nasr, Rucha Gadgil, Audrey Brown and Kim Jackson

Introduction

Jacobsen syndrome (JS) is a rare congenital gene syndrome caused by partial deletion of the long arm of chromosome 11. It was first described by Jacobsen in 1973. It is also known as 11q terminal deletion disorder because the deletion occurs at the end of the long (q) arm of chromosome 11.

Incidence and Prevalence

Jacobsen syndrome is an uncommon genetic syndrome, with around 200 cases reported worldwide. The prevalence of JS has been estimated to be at 1 in 100,000 newborns with a female/male ratio of 2:1. Around 8-15% of cases are caused by a deletion from a balanced parental chromosome translocation or rearrangement. Considering that 85092% of cases are of a de novo origin.

The severity of symptoms depends on the location and size of the deletion. The prevalence of Intellectual disability in individuals with JS is 97%. developmental delay 68-75%, platelet anomalies 88.5-94%, congenital cardiac malformation 56%, Around 20% of children die during the first two years of life, the main causes are complications of CHD and bleeding disorder caused by thrombocytopenia.

Etiology

It is caused mainly by loss of genetic material in chromosome 11 as an entirely random error in cell division in most cases. It can occur during the formation of reproductive cells or early on during fetal development. The number of genes deleted from the chromosome will determine how severe the disorder is.<article> 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.

Girls are twice as likely to develop this syndrome than boys.

Diagnosing Jacobsen syndrome can be difficult in some cases. This is because it is both a genetic condition and a rare one. Genetic testing is necessary to confirm a Jacobsen syndrome diagnosis.

During genetic testing, magnified chromosomes are evaluated under a microscope. They’re stained to give them a “barcode” appearance. The broken chromosome and the genes that have been deleted will be visible.

Jacobsen syndrome can be diagnosed during pregnancy. If an ultrasound flags anything abnormal, further testing may be done. A blood sample can be taken from the mother and analyzed.

Jacobsen syndrome can result in a large number of serious complications.

Learning disabilities affect about 97 percent of individuals with Jacobsen syndrome. These learning difficulties are typically mild to moderate. They can be severe.

Bleeding disorders are a serious but common complication of Jacobsen syndrome. About 88 percent of children with Jacobsen syndrome are born with Paris-Trousseau syndrome. This is a bleeding disorder that makes you bruise easily or bleed a lot. This can put you at a risk for internal bleeding. Even nosebleeds or blood work can result in heavy blood loss.

Heart conditions are also a common complication. About 56 percent of children with Jacobsen syndrome are born with heart conditions. Some of these will need surgery to be treated. About 20 percent of children with Jacobsen will die of heart complications before they’re 2 years old. Common heart defects include:

• holes between the left and right lower chambers
• abnormalities on the left side of the heart
• hypoplastic left heart syndrome, a defect that affects blood flow through the heart

Kidney problems can occur in infants and children with Jacobsen. Kidney problems include:

• having a single kidney
• double ureters (the tubes leading from the kidneys to the bladder)
• hydroneprosis, or swelling
• cysts

Gastrointestinal problems commonly affect infants with this condition. Pyloric stenosis causes forceful vomiting because of a narrowed or blocked outlet from the stomachs to the intestines. Other common problems include:

• blocked or narrow anus
• constipation
• intestinal obstruction
• missing parts of the GI tract
• abnormal positioning of the gut

Many children with Jacobsen have eye disorders that affect their sight, but a lot of these complications can be treated. Some children will develop cataracts.

Because some children with Jacobsen syndrome are immunodeficient, they may be much more susceptible to infections. Ear and sinus infections are especially common. Some children will have such severe ear infections they may get hearing loss.

Having a child with Jacobsen syndrome can be difficult for parents, especially since the disorder is so rare. Finding support can help you cope and give you the tools you need to help your child. Your child’s pediatrician may have suggestions for where you can find support.

Other great resources for parents of children with Jacobsen syndrome include:

• 11q Research & Resource Group
• Chromosome Disorder Outreach
• Unique- Rare Chromosome Disorder Support Group

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.<section> ADVERTISEMENT

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FIND A THERAPIST </section></article>Last medically reviewed on November 28, 2016<header> 3 sourcescollapsed </header>

[null FEEDBACK:]<section><section> Medically reviewed by University of Illinois — Written by Ana Gotter — Updated on July 8, 2017 </section>

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Clinical Presentation

Jacobsen Syndrome

1. Growth retardation: weight and height below the 5^th percentile.
2. Craniofacial dysmorphism: trigonocephaly, high prominent forehead, flat occiput, thin and brittle hair, down slanting palpebral fissure, palpebral ptosis, epicanthal folds, iris coloboma, arched eyebrows, hyper-telorism, small and low set ears, short nose with large and depressed nasal bridge, anteverted nostrils, down turning corners of the mouth, large mouth, high palate, dental anomalies, micrognathia.
3. Limbs anomalies: brachydactyly, clinodactyly, comptodactyly, bilateral simian crease, clubfoot, muscular atrophy, stiff joints, pectus excavatum, dorsal scoliosis, lumbar lordosis.
4. Cognitive Impairments
5. Neuromotor and psychiatric disabilities: delayed standing and walking, compulsive, hetero-aggressive and auto-aggressive behavior. Increased possibility of autism spectrum disorder characterized by impaired socialization and communication skills.
6. syndromic primary immune deficiency (SPID).
7. Most of the people with Jacobsen syndrome are diagnosed with  Paris-Trousseau syndrome which is a bleeding disorder.
8. Additional signs and symptoms appears in puberty: primary amenorrhea, genital infantilism, repeated episodes of sinusitis.
9. May also be diagnosed with ADHD

Diagnostic Procedures

Diagnosis is based on clinical findings (thrombocytopenia, intellectual deficit, and facial dysmorphic features) and must be confirmed by cytogenetics analysis. 

Differential Diagnosis

Some of the clinical features of children with Jacobsen syndrome are shared with Tuner and Noonan syndrome; such as short and wide neck, short stature, ptosis, pulmonary or aortic stenosis, and down-slanting palpebral fissure. Some children with JS have had clinical diagnosis of Kabuki syndrome due to mental retardation, unusual palpebral fissures, short stature, and finger-pads.

Management

Jacobsen syndrome is a chromosomal disorder in which children with JS will have a global developmental delays, presented by delayed motor and speech milestones. Hence, they should be referred to physical and/or occupational therapists in order to overcome the motor developmental delay.

Intensive neurodevelopmental treatment (Bobath approach) three times weekly, 60 minutes a day, for 3 months is recommended as it shows improved gross motor function and higher compliance than conventional NDT.

Bobath approach is developed through observation of the child and the desire to find the best solution to overcome the motor delay. Each child should be assessed in terms of individual movement expression and the potential to maximize their movement efficiency. Treatment cannot be repetitive or stereotype as it has to continuously adapt to the individual's progression. The Bobath approach is a goal-oriented and task-specific concept that aims to change the construct both the internal and external environment in which the individual and the nervous system can function efficiently and effectively.

Integrating play within NDT is proven to have many benefits in improving developmental delay. It improves cognitive and perceptual skills and acts as a stimuli for normal movement patterns by providing appropriate activities.

The adaptation of children with activity is essential for an effective play activity. That involves:

1. Adapting the shape, size and consistency of the used material.
2. Modifying the procedure and rules of the play activity.
3. Adjusting the position of materials and the child.
4. Controlling the degree of interpersonal interaction. If the motor demand is high, the cognitive demand has to be lowered to meet the changing needs f the child.