KBG syndrome (KBGS)

What is KBG syndrome (KBGS)?

KBG syndrome is a very rare genetic disorder. It is named from the initials of the first families diagnosed with the syndrome.

As a congenital malformation syndrome, distinctive facial features, facial dysmorphism, skeletal abnormalities, and intellectual disability are common symptoms of this rare disease.

Very often individuals with the syndrome are also diagnosed with autism spectrum disorder, hyperactivity and/or anxiety.

Syndrome Synonyms:
Dento-maxillo-facial syndrome; Macrodontia, Mental Retardation, Characteristic Facies, Short Stature, and Skeletal Anomalies

What gene change causes KBG syndrome (KBGS)?

KBG syndrome occurs due to a mutation in the ANKRD11 gene. It is inherited in an autosomal dominant pattern.

In the case of autosomal dominant inheritance just one parent is the carrier of the gene mutation, and they have a 50% chance of passing it onto each of their children. Syndromes inherited in an autosomal dominant inheritance are caused by just one copy of the gene mutation.

However, due to the documentation of more severe male cases, an X-linked inheritance has also been suggested.

Syndromes inherited in an X-linked recessive pattern generally only affect males. Males only have one X chromosome, and so one copy of a gene mutation on it causes the syndrome. Females, with two X chromosomes, only one of which will be mutated, are not likely to be affected.

With syndromes inherited in an X-linked dominant pattern, a mutation in just one of the copies of the gene, causes the syndrome. This can be in one of the female X chromosomes, and in the one X chromosomes males have. Males tend to have more severe symptoms than females.

What are the main symptoms of KBG syndrome (KBGS)?

The main symptoms of KBG syndrome may vary between individuals and may also vary in the extent of their severity.

The syndrome’s typical facial characteristics include a triangular face, upturned nose, widely spaced eyes, bushy eyebrows, a thin upper lip, and a large nasal bridge. Large teeth and particularly large upper front teeth are characteristic of the syndrome, as are dental abnormalities.

Other potential symptoms include skeletal and bone abnormalities, congenital heart defects, hearing loss, and seizures.

Intellectual disability and developmental delay are also common amongst individuals diagnosed with the syndrome.

Possible clinical traits/features:
Long philtrum, Long palpebral fissure, Macrodontia, Low anterior hairline, Low posterior hairline, Low-set, posteriorly rotated ears, Narrow mouth, Anteverted nares, Macrotia, Intellectual disability, Abnormal form of the vertebral bodies, Abnormality of dental enamel, Aplasia/Hypoplasia of the eyebrow, Cervical ribs, Abnormality of the ribs, Abnormality of femur morphology, Abnormality of calvarial morphology, Widely-spaced maxillary central incisors, Radial deviation of finger, Reduced number of teeth, Vertebral arch anomaly, Clinodactyly, Telecanthus, Thick eyebrow, Microcephaly, Triangular face, Strabismus, Round face, Thoracic kyphosis, Vertebral fusion, Autosomal dominant inheritance, Oligodontia, Rib fusion, Single transverse palmar crease, Syndactyly, Short neck, Pointed chin, Postaxial hand polydactyly, Delayed skeletal maturation, Brachydactyly, Facial asymmetry, Finger syndactyly, Cryptorchidism, EEG abnormality, Cleft palate, Underdeveloped nasal alae, Global developmental delay, Cognitive impairment.

How is KBG syndrome (KBGS) diagnosed?

To find out if someone has a diagnosis of KBG syndrome (KBGS), it is important to have a consultation and evaluation with a clinical genetic specialist.  Specialists may also suggest specific genetic testing or other types of tests to help reach a diagnosis.  FDNA’s AI technology can help speed up the diagnostic process by analyzing facial features and other health information.