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

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

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

1. Supportive

• no treatment for underlying disorder
• control seizures

2. Prognosis

• oldest patients in their 40's but severely disabled

1. Jones, K.L.; Smith's Recognizable Patterns of Human Malformation (5th Edition); p. 208-209 (1997).