National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

FG syndrome


Other Names:
FGS; Opitz-Kaveggia syndrome; FGS1; FGS; Opitz-Kaveggia syndrome; FGS1; Mental retardation, large head, imperforate anus, congenital hypotonia, and partial agenesis of corpus callosum; Keller syndrome See More
Categories:
FG syndrome (FGS) is a genetic condition that affects many parts of the body and occurs almost exclusively in males. "FG" represents the surname initials of the first individuals diagnosed with the disorder. People with FG syndrome frequently have intellectual disability ranging from mild to severe, hypotonia, constipation and/or anal anomalies, a distinctive facial appearance, broad thumbs and great toes, a large head compared to body size (relative macrocephaly), and abnormalities of the corpus callosum. Medical problems including heart defects, seizures, undescended testicle, and an inguinal hernia have also been reported in some affected individuals. Researchers have identified five regions of the X chromosome that are linked to FG syndrome in affected families.[1] Mutations in the MED12 gene appears to be the most common cause of this disorder, leading to FG syndrome 1.[1][2][3] Other genes involved with FG syndrome include FLNA (FGS2), CASK (FGS4), UPF3B (FGS6), and  BRWD3 (FGS7).[1][2][4] FGS is inherited in an X-linked recessive pattern.[1] Individualized early intervention and educational services are important so that each child can reach their fullest potential.[3] 
Last updated: 3/16/2016

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.

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Medical Terms Other Names
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HPO ID
1%-4% of people have these symptoms
Feeding difficulties in infancy 0008872
Scoliosis 0002650
Seizure 0001250
Sensorineural hearing impairment 0000407
Percent of people who have these symptoms is not available through HPO
Abnormal heart morphology
Abnormality of the heart
Abnormally shaped heart
Heart defect
[ more ] 		0001627
Abnormality of the nasopharynx 0001739
Abnormality of the sternum
Sternal anomalies
0000766
Anal atresia
Absent anus
0002023
Anal stenosis
Narrowing of anal opening
0002025
Anteriorly placed anus 0001545
Attention deficit hyperactivity disorder
Attention deficit
Attention deficit disorder
Attention deficit-hyperactivity disorder
Attention deficits
Childhood attention deficit/hyperactivity disorder
[ more ] 		0007018
Broad hallux
Broad big toe
Wide big toe
[ more ] 		0010055
Broad thumb
Broad thumbs
Wide/broad thumb
[ more ] 		0011304
Camptodactyly
Permanent flexion of the finger or toe
0012385
Choanal atresia
Blockage of the rear opening of the nasal cavity
Obstruction of the rear opening of the nasal cavity
[ more ] 		0000453
Cleft palate
Cleft roof of mouth
0000175
Cleft upper lip
Harelip
0000204
Clinodactyly
Permanent curving of the finger
0030084
Constipation 0002019
Cryptorchidism
Undescended testes
Undescended testis
[ more ] 		0000028
Decreased body weight
Decreased weight
Low body weight
Low weight
Weight less than 3rd percentile
[ more ] 		0004325
Delayed closure of the anterior fontanelle
Later than typical closing of soft spot of skull
0001476
Delayed speech and language development
Deficiency of speech development
Delayed language development
Delayed speech
Delayed speech acquisition
Delayed speech development
Impaired speech and language development
Impaired speech development
Language delay
Language delayed
Language development deficit
Late-onset speech development
Poor language development
Speech and language delay
Speech and language difficulties
Speech delay
[ more ] 		0000750
Dental crowding
Crowded teeth
Dental overcrowding
Overcrowding of teeth
[ more ] 		0000678
Downslanted palpebral fissures
Downward slanting of the opening between the eyelids
0000494
Epicanthus
Eye folds
Prominent eye folds
[ more ] 		0000286
Facial wrinkling 0009762
Fine hair
Fine hair shaft
Fine hair texture
Thin hair shaft
Thin hair texture
[ more ] 		0002213
Frontal bossing 0002007
Frontal upsweep of hair
Cowlick
Frontal Cowlick
Upswept frontal hair
[ more ] 		0002236
Global developmental delay 0001263
Gray matter heterotopia 0002282
High pitched voice 0001620
Hydrocephalus
Too much cerebrospinal fluid in the brain
0000238
Hypertelorism
Wide-set eyes
Widely spaced eyes
[ more ] 		0000316
Hypospadias 0000047
Inguinal hernia 0000023
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation
[ more ] 		0001249
Intestinal malrotation 0002566
Joint contracture of the hand 0009473
Large forehead
Increased size of forehead
0002003
Long philtrum 0000343
Lumbar hyperlordosis
Excessive inward curvature of lower spine
0002938
Micrognathia
Little lower jaw
Small jaw
Small lower jaw
[ more ] 		0000347
Microtia, first degree 0011266
Motor delay 0001270
Multiple joint contractures 0002828
Narrow palate
Narrow roof of mouth
0000189
Neonatal hypotonia
Low muscle tone, in neonatal onset
0001319
Partial agenesis of the corpus callosum 0001338
Plagiocephaly
Flat head syndrome
Flattening of skull
Rhomboid shaped skull
[ more ] 		0001357
Postnatal macrocephaly 0005490
Prominent fingertip pads
Prominent finger pads
0001212
Prominent forehead
Pronounced forehead
Protruding forehead
[ more ] 		0011220
Prominent nose
Big nose
Disproportionately large nose
Increased nasal size
Increased size of nose
Large nose
Pronounced nose
[ more ] 		0000448
Protruding ear
Prominent ear
Prominent ears
[ more ] 		0000411
Pyloric stenosis 0002021
Radial deviation of finger 0009466
Sacral dimple
Spinal dimple
0000960
Short neck
Decreased length of neck
0000470
Short stature
Decreased body height
Small stature
[ more ] 		0004322
Single transverse palmar crease 0000954
Skin tags 0010609
Sparse hair 0008070
Split hand
Claw hand
Claw hand deformities
Claw hands
Claw-hand deformities
Split-hand
[ more ] 		0001171
Strabismus
Cross-eyed
Squint
Squint eyes
[ more ] 		0000486
Syndactyly
Webbed fingers or toes
0001159
Thick lower lip vermilion
Increased volume of lower lip
Plump lower lip
Prominent lower lip
[ more ] 		0000179
Umbilical hernia 0001537
Underdeveloped superior crus of antihelix 0011246
Wide anterior fontanel
Wider-than-typical soft spot of skull
0000260
Wide mouth
Broad mouth
Large mouth
[ more ] 		0000154
Wide nasal bridge
Broad nasal bridge
Broad nasal root
Broadened nasal bridge
Increased breadth of bridge of nose
Increased breadth of nasal bridge
Increased width of bridge of nose
Increased width of nasal bridge
Nasal bridge broad
Wide bridge of nose
Widened nasal bridge
[ more ] 		0000431
X-linked inheritance 0001417
X-linked recessive inheritance 0001419
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Last updated: 7/1/2020

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.
  • Orphanet lists international laboratories offering diagnostic testing for this condition.
Treatment is aimed at addressing the individual symptoms present in each case.[3][2][5] This often involves care by a team of providers which may include pediatricians, neurologists, cardiologists, surgeons, gastroenterologists, and psychologists.[5] Early intervention and special education services should be initiated as soon as possible so that each child can reach his fullest potential.[3][2][5]

GeneReviews provides a detailed list of management strategies.
Last updated: 3/16/2016
Serious complications of FG syndrome, such as heart defects, breathing complications, or gastrointestinal (GI) malformations, may shorten the lifespan of affected individuals. Long-term survival has been reported, and several individuals with FG syndrome 1 have survived beyond age 50.[3]
Last updated: 3/16/2016

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • The Centers for Mendelian Genomics program is working to discover the causes of rare genetic disorders. For more information about applying to the research study, please visit their website.

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

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 FG 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. 
    FG syndrome 1
    FG syndrome 2
    FG syndrome 3
    FG syndrome 4
    FG syndrome 5
  • 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 FG syndrome. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. FG syndrome. Genetics Home Reference. December 2012; https://ghr.nlm.nih.gov/condition/fg-syndrome.
  2. Opitz J. FG syndrome. Orphanet. May 2009; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=323.
  3. Lyons MJ. MED12-Related Disorders. GeneReviews. June 6, 2013; http://www.ncbi.nlm.nih.gov/books/NBK1676/.
  4. OPITZ-KAVEGGIA SYNDROME. Online Mendelian Inheritance in Man (OMIM). March 21, 2012; http://www.omim.org/entry/305450.
  5. Lyons MJ. FG Syndrome Type 1. National Organization for Rare Disorders (NORD). 2015; http://rarediseases.org/rare-diseases/fg-syndrome-type-1/.