Pallister-Killian Syndrome

Introduction

Pallister-Killian syndrome (PKS) has a prevalence of approximately 1 in 25,000. It is a dysmorphic condition caused by mosaic tissue-limited tetrasomy of chromosome 12p. This is seen as an additional small metacentric isochromosome i(12)(p10). A proportion of fibroblasts (30-100%) will have tetrasomy 12p; however the karyotype of lymphocytes is normal. The main features include profound intellectual deficiency, seizures and streaks of skin hypo- or hyper-pigmentation. Facial features include a prominent forehead with sparse anterior scalp hair, sparse eyebrows and lashes, flattening of the head, wide-set eyes, short nose with anteverted nostrils, flat nasal bridge, a large mouth with downturned corners and a prominent upper lip, a protruding tongue and a short neck. Prenatal diagnosis may be possible through ultrasound scan findings such as diaphragmatic hernia, polyhydramnios, fetal hydrops, cardiac malformations, and short limbs. All reported cases of Pallister-Killian syndrome have arisen sporadically.

Referral information

Prenatal referrals where a diaphragmatic hernia has been detected on ultrasound scan are tested for Pallister-Killian syndrome by microarray studies on an uncultured amniotic fluid sample. Pallister-Killian syndrome cannot be detected in blood samples and so this service is not offered. However, we do accept skin biopsy samples from patients with appropriate clinical features for a diagnosis of Pallister-Killian syndrome. It is recommended that a skin sample from more than one site is tested. Buccal swab samples may also be accepted for FISH studies to exclude i(12p), following prior arrangement with the laboratory.

Price & reporting times

NHS referrals to this service are paid for where there is an existing specialist commissioning contract for genetic testing. In other cases please contact the laboratory for prices.

Test Price (£ ex VAT) TRT *
Postnatal solid tissue or buccal swab sample POA 28 cd
Prenatal amniotic fluid sample POA 14 cd

Test validation & quality assurance - information for users

For FISH studies, the Cytocell 12 centromere (D12Z1) probe is used in conjunction with the Abbott Molecular 12p subtelomeric probe (8M16/SP6). For microarray analysis, the OGT CytoSure Constitutional v3 8x60k array is used, sold for research use only. Due to probe distribution and density, all sizing information provided on reports is approximate. Anomalies may occur which cannot always be recognised or properly interpreted. Microarray analysis will not detect balanced rearrangements or polyploidy and may not detect unbalanced rearrangements present in low level mosaic form. aCGH does not provide any positional information. Analysis parameters are subject to change. The level of mosaicism detected during chromosome analysis may not necessarily reflect the level and distribution of cells with tetrasomy 12p in other tissues.

Referral guidelines

Please see our referral guidelines for more information.

OMIM Number(s) - 601803

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