Kabuki Syndrome

Kabuki syndrome is a rare phenomenon in clinical practice, but several distinct features distinguish this syndrome from an array of disorders presenting with similar signs and symptoms [1] [2] [3] [4]:

• Facial changes - Virtually all patients suffering from Kabuki syndrome have large, cupped ears, very broad and arched eyebrows, elongated palpebral fissures that are often accompanied by eversion of the lower lid (particularly the lateral third), and a depressed nasal tip [1] [4].
• Intellectual disability - Present in up to 92% of patients, intellectual impairment is an important manifestation of Kabuki syndrome [2] [4]. Many patients often have a delayed development of speech along with difficulties in cognition and understanding of words [2] [4].
• Growth deficiency - Despite having a normal height at birth, postnatal growth retardation is reported in a significant percentage of cases [1] [3] [4].
• Skeletal anomalies - Malformation of the spinal column (scoliosis, vertebral deformities), a cleft hand, brachydactyly, a shortened fifth finger of the hand, and underdeveloped ribs are notable disorders of the skeletal system [1] [2] [4].
• Skin - persistent fetal finger pads and abnormal dermatoglyphic patterns are hallmarks of Kabuki syndrome [1] [2] [3] [4].

In addition to these five crucial types of changes, other manifestations may stem from the cardiovascular system (mainly in the form of congenital heart disease such as coarctation of the aorta, atrial septal defects, and ventricular septal defects), gastrointestinal system (anal atresia), the eye (ptosis, strabismus), and the oral cavity (hypodontia and widely spaced teeth) [1] [2] [3] [4]. Furthermore, hearing loss, predisposition to infections and autoimmune diseases, and feeding issues are also noted [1] [2] [3] [4].

Because the diagnosis is primarily based on clinical criteria (but also because the disorder could be life-threatening in the absence of early recognition, particularly if congenital heart disease is present), a thorough clinical assessment is vital. The physician must take a detailed patient history during which the onset of symptoms and signs and their progression should be evaluated. Some studies have established the autosomal dominant pattern of inheritance in a significant number of patients meaning that a family history might provide important clues to the diagnosis [1] [2]. The majority of signs can be detected at the physical examination, but certain imaging studies may be necessary. As congenital heart diseases are often present [2], cardiac ultrasonography is a useful study. Once solid evidence is raised through clinical findings, genetic studies should be sought. Many patients develop Kabuki syndrome without a familial component (through de novo mutations) [1] [2]. The analysis of two genes - KMT2D (involved in the autosomal dominant form) and KDM6A (responsible for sporadic forms) will confirm the diagnosis [1] [2] [3] [4] [5] [6].

1. Adam MP, Hudgins L, Hannibal M. Kabuki Syndrome. 2011 Sep 1 [Updated 2013 May 16]. In: Pagon RA, Adam MP, Ardinger HH, et al., eds. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017.
2. Cheon C-K, Ko JM. Kabuki syndrome: clinical and molecular characteristics. Korean J Pediatr. 2015;58(9):317-324.
3. Hannibal MC, Buckingham KJ, Ng SB, Ming JE, et al. Spectrum of MLL2 (ALR) mutations in 110 cases of Kabuki syndrome. Am J Med Genet A. 2011;155A:1511–1516.
4. Kasdon BD, Fox JE. Kabuki syndrome: diagnostic and treatment considerations. Ment Health Fam Med. 2012;9(3):171-179.
5. Makrythanasis P, van Bon BW, Steehouwer M, et al. MLL2 mutation detected in 86 patients with Kabuki syndrome; a genotype-phenotype study. Clin Genet. 2013;84:539–545.
6. Ng SB, Bigham AW, Buckingham KJ, et al. Exome sequencing identifies MLL2 mutations as a cause of Kabuki syndrome. Nat Genet. 2010;42:790–793.