DESCRIPTION
Pallister-Killian Syndrome can also be found with the following
Synonyms:Chromosome 12, Isochromosome 12p Mosaic
Killian Syndrome
Killian/Teschler-Nicola Syndrome
Pallister Mosaic Syndrome
Pallister Mosaic Syndrome Tetrasomy 12p
According to the NORD (National Organization for Rare Disorders) Pallister-Killian Mosaic Syndrome is a rare chromosomal disorder that occurs for no apparent reason. Major symptoms may include a coarse face with a high forehead, sparse hair on the scalp, an abnormally wide space between the eyes, a fold of the skin over the inner corner of the eyes, and a broad nasal bridge with a highly arched palate. Mental retardation, loss of muscle tone, and streaks of skin lacking color are often present.
SYMPTOMS: Patients with Pallister-Killian Mosaic Syndrome typically have low muscle tone at birth, sparse scalp hair at birth, a high forehead, a coarse face, an abnormally wide space between the eyes, a broad nasal bridge, a highly arched palate, a fold of the skin over the inner corner of the eyes, and large ears with lobes that are thick and protrude outward. Other features frequently found in patients with this disorder may include: streaks of skin in which there is no color (hypopigmentation), extra nipples, seizures at birth, droopy upper eyelids, crossed eyes (strabismus), joints that will not move (contractures), and delays in perceiving, recognizing, judging, sensing, reasoning or imagining (cognitive delays). Congenital heart defects, hernia's of the diaphragm, a narrowing of the external auditory canal (stenosis) and an abnormal opening in the anus have also been associated with Pallister-Killian Mosaic Syndrome.
CAUSES: Pallister-Killian Mosaic Syndrome is caused by tetrasomy for chromosome 12p. Patients with Pallister-Killian Mosaic Syndrome have four copies of the short arm of chromosome 12 instead of the normal two. All recorded cases of this disorder have been sporadic (not believed to be hereditary).
PATHOGENESIS: Also called Killian/Teschler-Nicola Syndrome, Pallister Mosaic Syndrome, Tetrasomy 12p, Killian Syndrome, Teschler-Nicola/ Killian Syndrome the phenotypic features are due to the presence of four copies of chromosome 12p in affected cells the presence of the isochromosome 12p gives 4 copies of chromosome 12p in the affected cells
CLINICAL FEATURES:1. Neurological Manifestations
profound hypotonia at birth which persists
seizures usually beginning in infancy
developmental delay
hypotonia with joint contractures developing between 5-10 years of age
minimal speech development
mental retardation (usually profound)
sensorineuronal hearing loss
2. Craniofacial Features
bitemporal sparsity of scalp hair which grows in by 2-5 years
sparse eyebrows and eyelashes
prominent high forehead
progressive coarsening of the facies
prominent cheeks
large ears with thick protruding lobules
eyes:hypertelorism
epicanthal folds
upslanting palpebral fissures
strabismus
ptosis
nose:
flattened nasal bridge
short nose
anteverted nares
mouth:high-arched palate
long philtrum with thin upper lip with a cupid-bow shape
protruding lower lip
delayed dental eruption
3. Others
failure to thrive
postnatal deceleration of length and head circumference
generalized pigmentary dysplasia
sparse hypopigmented macules
streaks of hyper- and hypopigmentation
accessory nipples
laryngomalacia
gastroesophageal reflux (up to 6 months)
cataracts
congenital heart defects
diaphragmatic hernia
