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This
information was gleaned from PEDBASE. Their link is below.
Pediatric Database (PEDBASE)
Discipline: GEN
Last Updated: 4/17/97
PALLISTER-KILLIAN MOSAIC SYNDROME
DEFINITION-
A congenital disorder caused by chromosome 12p tetrasomy in affected cells
resulting in distinct craniofacial features and neurological manifestations.
EPIDEMIOLOGY-
incidence: rare, over 30 cases reported
age of onset: birth
risk factors: sporadic, M = F
PATHOGENESIS-
1. Background: 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, cataracts, congenital heart defects, diaphragmatic
hernia
INVESTIGATIONS-
1. Chromosomal Analyses: diagnostic, skin fibroblast chromosomes show either
a mosaic or total tetrasomy for chromosome 12p, FISH (fluorescent in situ
hybridization) may be used with specific chromosome 12 DNA probes to detect
isochromosome 12p, prenatal diagnosis is possible using amniocentesis or
chorionic villus sampling, chromosomes obtained from peripheral blood are
usually normal but there may be a lymphocyte mosaicism for an isochromosome of
12p in some patients
2. Imaging Studies: CT (Head), cerebral atrophy
MANAGEMENT-
1. Supportive: no treatment for underlying disorder, control seizures
2. Prognosis: oldest patients in their 40's but severely disabled
ADDITIONAL REFERENCES-
1. Jones, K.L.; Smith's Recognizable Patterns of Human Malformation (5th
Edition); p. 208-209 (1997)
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