Rare Rheumatology News

Disease Profile

KBG syndrome

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
<1 / 1 000 000

< 331

US Estimated

< 514

Europe Estimated

Age of onset

Childhood

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ICD-10

Q87.8

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Categories

Congenital and Genetic Diseases; Mouth Diseases; Nervous System Diseases

Summary

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.[1][2]

Symptoms

KBG syndrome is often characterized by distinctive facial features, skeletal abnormalities, short stature, large upper teeth (macrodontia), and developmental delay or intellectual disability.[3][4] However, the number and severity of symptoms can vary.[3]

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.[1] In addition to macrodontia, affected people may have jagged or misaligned teeth and/or other abnormalities of the bones or sockets of the jaw.[3]

Skeletal abnormalities most often affect the limbs, spine, and/or ribs.[3][1] Affected people often have delayed bone age.[1] 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.[4]

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
HPO ID
30%-79% of people have these symptoms
Abnormal hair pattern
Abnormal distribution of hair
0010720
Anteverted nares
Nasal tip, upturned
Upturned nasal tip
Upturned nose
Upturned nostrils

[ more ]

0000463
Bilateral conductive hearing impairment
0008513
Cervical ribs
0000891
Cleft palate
Cleft roof of mouth
0000175
Cryptorchidism
Undescended testes
Undescended testis

[ more ]

0000028
Cutaneous syndactyly
0012725
Delayed skeletal maturation
Delayed bone maturation
Delayed skeletal development

[ more ]

0002750
Feeding difficulties
Feeding problems
Poor feeding

[ more ]

0011968
Finger clinodactyly
0040019
Global developmental delay
0001263
Hypertelorism
Wide-set eyes
Widely spaced eyes

[ more ]

0000316
Long palpebral fissure
Broad opening between the eyelids
Long opening between the eyelids
Wide opening between the eyelids

[ more ]

0000637
Long philtrum
0000343
Macrodontia
Increased width of tooth
0001572
Macrotia
Large ears
0000400
Microcephaly
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference

[ more ]

0000252
Oligodontia
Failure of development of more than six teeth
0000677
Prominent nasal bridge
Elevated nasal bridge
High nasal bridge
Prominent bridge of nose
Prominent nasal root
Protruding bridge of nose
Protruding nasal bridge

[ more ]

0000426
Scoliosis
0002650
Short neck
Decreased length of neck
0000470
Short stature
Decreased body height
Small stature

[ more ]

0004322
Single transverse palmar crease
0000954
Strabismus
Cross-eyed
Squint
Squint eyes

[ more ]

0000486
Synophrys
Monobrow
Unibrow

[ more ]

0000664
Telecanthus
Corners of eye widely separated
0000506
Thick eyebrow
Bushy eyebrows
Dense eyebrow
Heavy eyebrows
Prominent eyebrows
Thick eyebrows

[ more ]

0000574
Thin upper lip vermilion
Thin upper lip
0000219
Thoracic kyphosis
0002942
Triangular face
Face with broad temples and narrow chin
Triangular facial shape

[ more ]

0000325
Underdeveloped nasal alae
Underdeveloped tissue around nostril
0000430
Vertebral fusion
Spinal fusion
0002948
Webbed neck
Neck webbing
0000465
Widely-spaced maxillary central incisors
Gap between upper front teeth
Wide gap between upper central incisors
Widely spaced upper incisors

[ more ]

0001566
5%-29% of people have these symptoms
Congenital malformation of the left heart
0045017
EEG abnormality
0002353
Persistent open anterior fontanelle
0004474
Round face
Circular face
Round facial appearance
Round facial shape

[ more ]

0000311
Seizure
0001250
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
0000006
Clinodactyly
Permanent curving of the finger
0030084
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation

[ more ]

0001249
Low anterior hairline
Low frontal hairline
Low-set frontal hairline

[ more ]

0000294
Low posterior hairline
Low hairline at back of neck
0002162
Radial deviation of finger
0009466
Rib fusion
Fused ribs
0000902
Syndactyly
Webbed fingers or toes
0001159
Vertebral arch anomaly
0008438

Diagnosis

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

    Organizations

    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Organizations Providing General Support

        Learn more

        These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

        Where to Start

        • Genetics Home Reference (GHR) contains information on KBG syndrome. This website is maintained by the National Library of Medicine.
        • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

          In-Depth Information

          • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
          • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
          • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
          • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
          • PubMed is a searchable database of medical literature and lists journal articles that discuss KBG syndrome. Click on the link to view a sample search on this topic.

            References

            1. KBG syndrome. Genetics Home Reference. January, 2015; https://ghr.nlm.nih.gov/condition/kbg-syndrome.
            2. Marla J. F. O'Neill. KBG SYNDROME; KBGS. OMIM. September 12, 2011; https://www.omim.org/entry/148050.
            3. KBG Syndrome. NORD. 2003; https://rarediseases.org/rare-diseases/kbg-syndrome/.
            4. Francesco Brancati, Bruno Dallapiccola, Anna Sarkozy. KBG syndrome. Orphanet. December, 2006; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=2332.

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