tetrasomy 12p true ICD10:Q99.8 Pallister-Killian syndrome (PKS) is a rare multiple congenital anomaly/intellectual deficit syndrome caused by mosaic tissue-limited tetrasomy for chromosome 12p. Pallister-Killian syndrome Pallister-Killian mosaic syndrome Hexasomy 12P, Mosaic Orphanet:884 GARD:0008421 Isochromosome 12P syndrome tetrasomy type 12p Pallister Killian syndrome SCTID:9527009 OMIM:601803 Killian syndrome MONDO:0011146 UMLS:C0265449 This chromosomal abnormality results in dysmorphic features that include a coarsened flat facies, high forehead, reduced scalp hair over the frontal and temporal regions, hypertelorism, a broad nasal bridge, a small anteverted nose, a high arched palate, microretrognathia, a cupid-bow shaped upper lip and low-set ears. There may be cardiac, diaphragmatic and ocular abnormalities. There is developmental delay, severe intellectual impairment and epilepsy. Seizures of varied types have been reported, including epileptic spasms. The disorder is sporadic. Most patients are mosaic for tetrasomy 12p and it may be undetectable in blood lymphocytes. To diagnose this disorder, examination of fibroblasts may be required. Teschler-Nicola Killian syndrome Pallister mosaic syndrome PKS MESH:C538105 Isochromosome 12p mosaicism Killian Teschler-Nicola syndrome ICD9:758.81 Isochromosome 12p syndrome chromosome 12, Isochromosome 12p syndrome Pallister-Killian syndrome; PKS tetrasomy 12P, Mosaic NCIT:C75458 chromosomal anomaly