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 Human Phenotype Ontology provides the following list of signs and symptoms for KBG syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Abnormal form of the vertebral bodies 90% Abnormality of calvarial morphology 90% Abnormality of the femur 90% Abnormality of the ribs 90% Aplasia/Hypoplasia of the eyebrow 90% Brachydactyly syndrome 90% Cognitive impairment 90% Delayed skeletal maturation 90% Macrodontia 90% Round face 90% Short stature 90% Telecanthus 90% EEG abnormality 50% Finger syndactyly 50% Hypertelorism 50% Low posterior hairline 50% Low-set, posteriorly rotated ears 50% Narrow mouth 50% Reduced number of teeth 50% Short neck 50% Single transverse palmar crease 50% Strabismus 50% Abnormality of dental enamel 7.5% Cleft palate 7.5% Cryptorchidism 7.5% Facial asymmetry 7.5% Hearing impairment 7.5% Pointed chin 7.5% Postaxial hand polydactyly 7.5% Anteverted nares - Autosomal dominant inheritance - Cervical ribs - Clinodactyly - Intellectual disability - Long palpebral fissure - Long philtrum - Low anterior hairline - Macrotia - Microcephaly - Oligodontia - Radial deviation of finger - Rib fusion - Syndactyly - Thick eyebrow - Thoracic kyphosis - Triangular face - Underdeveloped nasal alae - Vertebral fusion - Widely-spaced maxillary central incisors - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.