Cytogenomic delineation and clinical follow-up of 10 Brazilian patients with Pallister-Killian syndrome

Abstract

Background: Pallister-Killian syndrome (PKS) is a sporadic genetic disorder caused by the presence of a tissue-specific mosaicism for isochromosome 12p - i(12) (p10) and is characterized by facial dysmorphism including coarse facies, upslanting palpebral fissures, bitemporal alopecia, pigmentary skin anomalies, developmental delay, hypotonia and seizures. Although typical clinical features of PKS commonly exist, clinicians often do not raise the possibility of this diagnosis.

Results: We reviewed the medical records of 10 patients with confirmed PKS followed in our service (since 1990 to 2015). Age at diagnosis varied from prenatal to 3 years and clinical features were consistent with those described in the literature. In all patients, peripheral blood karyotypes were normal and cytogenomic study was performed in order to confirm the diagnosis. Three of these patients had PKS diagnosis confirmed by buccal smear MLPA.

Conclusion: An early conclusion from our results demonstrated that MLPA on buccal smears is a good and non-invasive method to detect extra copies of 12p and should be considered as the first exam, before a skin biopsy for a fibroblast karyotype is performed.

Keywords: Buccal smear; MLPA; Pallister-Killian syndrome; isochromosome 12p.

Fig. 1

a and b: Histogram showing MLPA analysis of DNA from buccal smear; c: FISH in interphase cells showing 12p specific subtelomeric probe (Aquarius®, Cytocell Cambridge, UK ) hybridization; d: Fibroblast skin karyotype showing isochromosome 12p in G band

Fig. 2

Patient # 5: dysmorphic features described in PKS: frontotemporal alopecia, hypertelorism, anteverted nostrils, long philtrum with “Pallister lip”, hypopigmented streaks. a: frontal view; b: lateral view