Pallister-Killian syndrome (PKS) is an extremly rare chromosomal anomaly.
It may be more prevalent in woman of advanced age 4.
It is a polymalformative complex with tetrasomy of isochromosome 12p although many cases are mosaic.
The majority of cases are through to be sporadic but in some cases, the degree of mosaicism in the chorion villus sample is much more lower than that in the fetal tissues subsequently examined. Confined placental mosaicism is a well-recognized phenomenon in a number of chromosomal abnormalities and is said to contribute to their intra-uterine survival.
Tetrasomy 12p is not always diagnosed, because the tissues are differently affected. Although it is present in a high percentage of fibroblasts, it is practically absent from the blood.
Phenotypic expression can siginifcantly vary from multiple anomalies resulting in perinatal death to the more characteristic situation of
- profound mental retardation
- coarse facial appearance
- pigmentary anomalies
- localised alopecia in the temporofrontal area
- long philtrum
- acral hypoplasia
Other anomalies include
- anteverted nostrils
- small and apparently low-set ears
- simian crease
- congenital heart disease : may be seen in up to 25% of cases 4
- congenital diaphragmatic hernia : may be seen in up to 50% of cases 4
- rhizomelic limb shortening
The mosiac forms make diagnosis difficult
May show a comibation of some of the above clinical features. There may be polyhydramnios as an ancillary sonographic feature 2.
Some of the clinical features can overlap with the Fryns syndrome 1
- 2. Wilson RD, Harrison K, Clarke LA et-al. Tetrasomy 12p (Pallister-Killian syndrome): ultrasound indicators and confirmation by interphase fish. Prenat. Diagn. 1994;14 (9): 787-92. - Pubmed citation
- 1. Paladini D, Borghese A, Arienzo M et-al. Prospective ultrasound diagnosis of Pallister-Killian syndrome in the second trimester of pregnancy: the importance of the fetal facial profile. Prenat. Diagn. 2000;20 (12): 996-8. Prenat. Diagn. (link) - Pubmed citation
- 3. Doray B, Girard-lemaire F, Gasser B et-al. Pallister-Killian syndrome: difficulties of prenatal diagnosis. Prenat. Diagn. 2002;22 (6): 470-7. doi:10.1002/pd.342 - Pubmed citation
- 4. Entezami M, Knoll U. Ultrasound diagnosis of fetal anomalies. Thieme Publishing Group. (2004) ISBN:3131318619. Read it at Google Books - Find it at Amazon