Kabuki syndrome acquired its name because the facial features of the children resembled the make-up of the actors in the traditional Kabuki theatre. Kabuki syndrome is often unrecognized in the newborn and it may take several years for the features to become obvious in the child. The facial characteristics of Kabuki include:
long palpebral fissures
lower palpebral eversion
arched eyebrows with sparse outer lateral half
depressed nasal tip
prominent broad philtrum
cleft lip/palate or arched palate
Most noteable in children with Kabuki syndrome are the large eyes, long and thick eyelashes, arched eyebrows, flat nasal tip and prominent ears. Outer lower lid eversion can contribute to sleeping with eyes partially open.
Ocular conditions that occur more commonly in KS than the general population are blue sclerae, strabismus, coloboma and ptosis. Less common conditions can include nystagmus, Peters’ anomaly, and Marcus Gunn’s phenomenon.
Ears are frequently large, cupped, and incompletely formed. Hearing loss has usually been attributed to both repeated ear infections and sensorineural problems.
Cleft palate/lip or high arched palates are commonly found. A thin upper lip has also been noted. Teeth are often wide spaced, irregularly shaped and misaligned. Hypodontia is common, in particular missing upper incisors. Delay in speech and language acquisition is very common, exacerbated by craniofacial anomalies, hypotonia, and poor coordination.
There are numerous skeletal anomalies found in children with Kabuki syndrome, ranging from rib anomalies to more significant issues such as scoliosis. Hypotonia and lax ligaments can contribute to dislocations of the hip in early childhood and patellar dislocations during puberty years. The musculoskeletal characteristics of Kabuki syndrome include:
short middle phalanx of fifth finger
syndactyly - mild webbing between fingers
dislocations of hip, patella and shoulders
Vertebral anomalies can include butterfly vertebra, sagittal cleft, narrow intervertebral disc space, spina bifida occulta, and scoliosis. Joint hypermobility is very common, in particular in the younger child. The hypermobility, exacerbated by hypotonia, can lead to dislocation of joints, in particular the hip, knees and shoulders. It is yet unclear whether joint laxity is neurogenic or due to a connective tissue disorder. Short fingers, in particular the fifth finger, is common. Webbing between the fingers is less commonly seen.
Intellectual: Most individuals with Kabuki syndrome have mild to moderate intellectual disability, with a small percentage falling in the severe range. Limited research exists on specific developmental outcomes, however one study dedicated specifically to intellectual and adaptive behaviors identified a clear pattern of weakness in visuospatial construction and relative strength in verbal and non-verbal reasoning. Another published article, describing the long-term follow-up of three individuals, found that although they were able to achieve independent daily living skills and hold part-time jobs, they required sheltered living environments.
While some level of intellectual disability is common among individuals with Kabuki syndrome, parents can continue to have high expectations for their affected children. Children with Kabuki syndrome can be helped to achieve their own highest potential through early intervention and therapy. Additionally, appropriate long-term planning for transition to adulthood and independence is essential.
Neurological: Various neurological issues exist among individuals with Kabuki syndrome. Most common is hypotonia which can hamper motor development and feeding. Studies do show that hypotonia can improve with age. Other neurological abnormalities include microcephaly and seizures. There does not appear to be any one type of seizure associated with KS, although the majority have localization-related epilepsy. The age of onset can range from infancy to middle childhood.
Postnatal short stature is one of the cardinal features of Kabuki syndrome. It is still unclear as to what extent growth hormone deficiency contributes to this characteristic.
Although birth weight and length are generally normal, growth delay often starts during the first year of life. Poorly coordinated sucking and swallowing, reflux, recurrent infections, cardiac defects, and hypotonia may all be contributing factors. Although growth hormone levels are in the normal range for most children, a significant number have a partial or complete deficiency. Obesity seems to be a common problem during puberty years. The adult with Kabuki will be shorter than the norm – two or more standard deviations below the mean.
Approximately half the children diagnosed with Kabuki syndrome will have a cardiovascular malformation. Diverse conditions are reported, but the most common are juxtaductal coarctation of the aorta, ventricular septal defect, and atrial septal defect. Often there is a combination of these defects in an infant.
Since the cardiac conditions are congenital, during the formation of the heart, no further defects should occur. Diagnosis of the cardiac conditions often occurs prior to diagnosis of Kabuki syndrome.
Conductive hearing loss is a common occurrence in individuals with Kabuki syndrome, usually due to repeated ear infections during childhood. Cleft palate, abnormal development of the eustachian tube and immunity deficiencies can all be contributing factors. Hearing loss in Kabuki syndrome can be of three basic types: conductive, sensorineural or mixed. Conductive hearing loss occurs when sound is not conducted properly through the outer ear, middle ear, or both, such as in ear canal obstruction or in acute otitis media (ear infection). It is generally a mild to moderate impairment because sound can still be detected by the inner ear. Generally, with pure conductive hearing loss, the quality of hearing (speech discrimination) is good, as long as the sound is amplified loud enough to be easily heard. This type of hearing impairment can often be medically or surgically treated.
Sensorineural hearing loss is due to the damage of the inner ear, the cochlea, or to the impairment of the auditory nerve. It can be mild, moderate, severe, or profound, to the point of total deafness. It is a permanent loss and it doesn’t only affect sound intensity such as the ability to hear faint sounds but also makes it more difficult for you to recognize complex sounds, to understand speech and to hear clearly.
Mixed hearing loss - In some cases, such as in complication of recurrent/chronic otitis media, a conductive hearing loss occurs in combination with damage of the inner ear or of the auditory nerve. When this occurs the hearing loss is referred to as a mixed hearing loss.
Conductive hearing loss, mainly due to recurrent otitis media, is reported with a frequency ranging from 24% to 82%. In fact chronic otitis media is extremely frequent in individuals with Kabuki syndrome during childhood. It is probably related either to cleft palate and abnormal development of the eustachian tube or to immune deficiency. It has to be cured in order to limit permanent hearing loss sequelae (mixed hearing loss).
Sensorineural hearing loss is very rare in Kabuki syndrome. Only a few cases are reported in the literature and are mainly caused by anomalies of the inner ear, however this low prevalence could also be due to incomplete neuro-radiological investigations (CT brain) reported up to now in the medical literature.
Some children may utilize a personal or classroom sound field FM system, either in conjunction with aids or without. The FM system enhances the distance to noise ratio, in the typical classroom, so that environmental/background noise is decreased while the voice of the speaker is amplified.
A significant number of individuals with Kabuki syndrome have optical anomalies. More common ocular conditions include blue sclerae, strabismus, coloboma, ptosis and micropthalmia. Less common conditions can include nystagmus, Peter's anomaly, and Marcus Gunn phenomenon, optic nerve hypoplasia, obstructed nasolacrimal ducts and refractive anomalies.
Many individuals with Kabuki syndrome have sensory processing disorder. This inability to accurately organize sensory information can lead to behavior problems. Some of the more commonly reported sensory issues include need for oral stimulation - including chewing on non-food items, tactile defensiveness towards various sensations and stimuli, panic-like reactions to certain noises, and aversion to textures and/or smells of select foods. Anxiety, obsessive/compulsive traits and autistic-type behaviors are commonly observed. Individuals with Kabuki syndrome often have an obsessive need for routine. Mild depression has been reported in young adults. Parents frequently report an excellent memory for face recognition, song lyrics, dates of events, etc.