What are the other Names for this Condition? (Also known as/Synonyms)

• Short Stature, Characteristic Facies, Macrodontia, Mental Retardation, and Skeletal Anomalies

What is KBG Syndrome? (Definition/Background Information)

• KBG Syndrome is a rare condition characterized mainly by skeletal abnormalities, distinctive facial features, and intellectual disability
• Specific signs and symptoms may include delayed bone age; abnormalities of the bones of the spine, ribs, and/or hands; large teeth (macrodontia); short stature; developmental delay; and behavioral or emotional issues. Less common features may include hearing loss, seizures, and congenital heart defects
• In some cases, KBG Syndrome is caused by a mutation in the ANKRD11 gene and is inherited in an autosomal dominant manner
• In other cases, the genetic cause is unclear. Some affected people inherit the condition from a parent, while in other people it occurs sporadically

(Source: KBG Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets KBG Syndrome? (Age and Sex Distribution)

• KBG Syndrome is a rare congenital disorder. The presentation of symptoms may occur at birth
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for KBG Syndrome? (Predisposing Factors)

• A positive family history may be an important risk factor, since KBG Syndrome is an inherited condition

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of KBG Syndrome? (Etiology)

• In some cases, KBG Syndrome is caused by a mutation in the ANKRD11 gene and is inherited in an autosomal dominant manner
• In other cases, the genetic cause is unclear. Some affected people inherit the condition from a parent, while in other people it occurs sporadically

(Source: KBG Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

What are the Signs and Symptoms of KBG Syndrome?

• KBG Syndrome is often characterized by distinctive facial features, skeletal abnormalities, short stature, large upper teeth (macrodontia), and developmental delay or intellectual disability. However, the number and severity of symptoms can vary
• Characteristic features of the head and face may include a wide, short skull (brachycephaly); triangular face shape; widely spaced eyes (hypertelorism); wide eyebrows that may connect (synophrys); prominent nasal bridge; a long space between the nose and upper lip; and a thin upper lip
• In addition to macrodontia, affected people may have jagged or misaligned teeth and/or other abnormalities of the bones or sockets of the jaw
• Skeletal abnormalities most often affect the limbs, spine, and/or ribs. Affected people often have delayed bone age
• Other signs and symptoms that have been less commonly reported include seizures; syndactyly; a webbed, short neck; undescended testes(cryptorchidism); hearing loss; defects of the palate (roof of the mouth); strabismus; and congenital heart defects

The number and severity of symptoms can vary, but are not limited to:

• Anteverted nares; abnormal nostrils
• Cervical ribs; extra ribs in the cervical region
• Clinodactyly; abnormal bending of the fingers
• Cryptorchidism; absence of testis/testes in the scrotal sac
• Delayed skeletal maturation
• Hypertelorism; increased space between two organs
• Intellectual disability
• Long palpebral fissure; a form of eye abnormality
• Long philtrum; increased space between the nose and the mouth
• Low anterior and low posterior hairline
• Macrodontia; presence of large teeth
• Macrotia; abnormally-increased ear size
• Microcephaly; small head size
• Oligodontia; absence of teeth
• Radial deviation of finger
• Rib fusion
• Round face
• Single transverse palmar crease
• Syndactyly or fused fingers/toes
• Telecanthus; increased spacing between the eyes
• Thick eyebrow
• Thoracic kyphosis; abnormally bent spine at the thoracic region
• Triangular face
• Underdeveloped nasal alae; abnormally-shaped nose
• Vertebral fusion
• Widely-spaced maxillary central incisors

(Source: KBG Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is KBG Syndrome Diagnosed?

KBG Syndrome is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the Possible Complications of KBG Syndrome?

The complications of KBG Syndrome may include:

• Severe physical deformity
• Intellectual disability
• Congenital heart defects

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is KBG Syndrome Treated?

There is no cure for KBG Syndrome, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complications that develops.

How can KBG Syndrome be Prevented?

Currently, KBG Syndrome is not preventable, since it may be a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of KBG Syndrome? (Outcomes/Resolutions)

• The prognosis of KBG Syndrome is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for KBG Syndrome:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/diseases-conditions/rare-disorders/