Pallister-Killian syndrome: a report of 2 cases and review of its surgical aspects

Structural brain abnormalities in Pallister-Killian syndrome: a neuroimaging study of 31 children

BACKGROUND

Pallister-Killian syndrome (PKS) is a rare genetic disorder caused by mosaic tetrasomy of 12p with wide neurological involvement. Intellectual disability, developmental delay, behavioral problems, epilepsy, sleep disturbances, and brain malformations have been described in most individuals, with a broad phenotypic spectrum. This observational study, conducted through brain MRI scan analysis on a cohort of patients with genetically confirmed PKS, aims to systematically investigate the neuroradiological features of this syndrome and identify the possible existence of a typical pattern. Moreover, a literature review differentiating the different types of neuroimaging data was conducted for comparison with our population.

RESULTS

Thirty-one individuals were enrolled (17 females/14 males; age range 0.1-17.5 years old at first MRI). An experienced pediatric neuroradiologist reviewed brain MRIs, blindly to clinical data. Brain abnormalities were observed in all but one individual (compared to the 34% frequency found in the literature review). Corpus callosum abnormalities were found in 20/30 (67%) patients: 6 had callosal hypoplasia; 8 had global hypoplasia with hypoplastic splenium; 4 had only hypoplastic splenium; and 2 had a thin corpus callosum. Cerebral hypoplasia/atrophy was found in 23/31 (74%) and ventriculomegaly in 20/31 (65%). Other frequent features were the enlargement of the cisterna magna in 15/30 (50%) and polymicrogyria in 14/29 (48%). Conversely, the frequency of the latter was found to be 4% from the literature review. Notably, in our population, polymicrogyria was in the perisylvian area in all 14 cases, and it was bilateral in 10/14.

CONCLUSIONS

Brain abnormalities are very common in PKS and occur much more frequently than previously reported. Bilateral perisylvian polymicrogyria was a main aspect of our population. Our findings provide an additional tool for early diagnosis.Further studies to investigate the possible correlations with both genotype and phenotype may help to define the etiopathogenesis of the neurologic phenotype of this syndrome.

Polymicrogyria with calcification in Pallister-Killian syndrome detected by microarray analysis

BACKGROUND

Pallister-Killian syndrome (PKS) is a rare disorder caused by the mosaic tetrasomy of chromosome 12p, and is characterized by facial dysmorphism, developmental delay, hypotonia and seizures.

RESULTS

We report a patient with PKS showing unique polymicrogyria with calcification. He had delayed development and dysmorphic facial features including frontal bossing, hypertelorism, and high arched palate at 6 months of age. Neuroimaging revealed unilateral polymicrogyria with spot calcifications, which predominantly affected the right perisylvian region. Chromosome G-banding showed the karyotype 46,XY, however, array-based comparative genomic hybridization analysis showed mosaic duplication of chromosome 12p, in which CCND2, which encodes cyclin D2 and is a downstream mediator of PI3K-AKT pathway, is located. Supernumerary chromosome of 12p was detected in 58% of buccal mucosa cells by the interphase fluorescence in situ hybridization analysis using chromosome 12 centromere-specific D12Z3 probe. The diagnosis of PKS was made based on distinctive clinical features of our patient and the results of cytogenetic analyses.

CONCLUSION

This report is, to our knowledge, the first case of a patient with PKS who clearly demonstrates polymicrogyria colocalized with calcifications, as shown by CT scans and MRI, and suggests that a patient with PKS could show structural brain anomalies with calcification. We assume that somatic mosaicism of tetrasomy could cause asymmetrical polymicrogyria in our patient, and speculate that increased dosages of CCND2 at chromosome 12p might be involved in the abnormal neuronal migration in PKS.

Clinical Variability of Pallister-Killian Syndrome in Two Egyptian Patients

Pallister-Killian syndrome (PKS) is a rare sporadic genetic disorder caused by a mosaic tetrasomy of chromosome 12p, which mainly manifests with craniofacial dysmorphism, intellectual disability (ID), auditory disturbance, epilepsy, and a variety of congenital malformations. The diagnosis of PKS can be complicated due to the phenotypic variation, and an overlap with other syndromes makes the molecular cytogenetic test necessary for a correct diagnosis. We identified two unrelated patients with typical facial features of PKS, including bitemporal alopecia, hypertelorism, and abnormal ears. Furthermore, the two patients had pigmentary skin anomalies, broad and short hands and fingers, and hypotonia. However, they differed in the degree of ID and ophthalmological findings. Patient 1 showed profound ID and poor macular function, whereas patient 2 had moderate ID and normal fundus. Mosaic tetrasomy of chromosome 12p was found in 40 and 25% of the cells of patients 1 and 2, respectively, by fluorescent in situ hybridization of cultured skin fibroblasts. The higher percentage of mosaic cells with tetrasomy 12p found in patient 1 may explain the severe phenotype. This report expands the clinical manifestations of PKS and highlights the variable expressivity of clinical features in relation to the cytogenetics findings.

Four children with postnatally diagnosed mosaic trisomy 12: Clinical features, literature review, and current diagnostic capabilities of genetic testing

Children or adults with mosaic trisomy 12 diagnosed postnatally are extremely rare. Only a small number of patients with this mosaicism have been reported in the literature. The clinical manifestation of mosaic trisomy 12 is variable, ranging from mild developmental delay to severe congenital anomaly and neonatal death. The trisomy 12 cells are not usually able to be detected by phytohemagglutinin stimulated peripheral blood chromosome analysis. The variability of phenotypes and the limited number of patients with this anomaly pose a challenge to predict the clinical outcomes. In this study, we present the phenotypes and laboratory findings in four patients and review the 11 previously reported patients with mosaic trisomy 12 diagnosed postnatally, as well as 11 patients with mosaic trisomy 12 diagnosed prenatally. The findings of this study provide useful information for laboratory diagnosis and clinical management of these patients.

Pallister-Killian Mosaic Syndrome in an Omani Newborn: A Case Report and Literature Review

Pallister-Killian mosaic syndrome (PKS) is a rare sporadic condition with multiple congenital anomalies and intellectual deficits caused by mosaic tissue-limited tetrasomy of the short arm of chromosome 12 (12p). The clinical features are highly variable, ranging from mild to severe. Diagnosis is usually missed because of the low level of mosaicism in peripheral lymphocytes. We present a case of an Omani newborn with PKS with severe clinical presentation and multisystem involvement that lead to postnatal death. Karyotype and fluorescent in situ hybridization studies confirmed the presence of chromosome 12p duplication. This is the first case of PKS reported in the literature from Oman and the Arab world.

Neuroimaging findings in Pallister-Killian syndrome

Pallister-Killian syndrome (PKS) is a rare chromosomal duplication disorder caused by additional copies of the short arm of chromosome 12 (12p). Clinically PKS is characterized by craniofacial dysmorphism with neonatal frontotemporal alopecia, hypertelorism, and low-set ears as well as kyphoscoliosis, severe intellectual disability, epilepsy, and abnormal muscle tone. Comprehensive high-resolution brain MR findings of PKS in childhood have not been previously illustrated in the medical literature. We present detailed neuroimaging findings from a child with PKS and thoroughly review previously reported structural brain abnormalities in this patient population. MRI abnormalities common to PKS include cerebral volume loss, malformations of cortical development, corpus callosum dysgenesis, white matter disease, and craniofacial malformations. In our patient, new findings of perisylvian with occipital polymicrogyria, vermian dysplasia, brachium pontis signal abnormality, dural anomalies, and unilateral atlas assimilation were noted. Micrencephaly and cortical dysplasia provide a likely explanation for severe intellectual disability and epilepsy in this patient population.

Dental Treatment of a Child with Pallister-Killian Syndrome

The Pallister-Killian syndrome (PKS) is an extremely rare genetic disorder with an incidence estimated around 1/25000. PKS is a multiple congenital anomaly deficit syndrome caused by mosaic tissue limited tetrasomy for chromosome 12p. The presented report is the first confirmed case with PKS in Turkey. This report focuses on the orofacial clinical manifestations of an 6-year-old boy with PKS who was referred to the Department of Paediatric Dentistry clinic, Gazi University. It has been learned that the PKS was diagnosed 1 year after birth. Due to intellectual disability, it was decided to make the dental treatments under moderate sedation. Although significant tongue thrust and anterior open bite were determined, any oral appliances could not be applied because of the 2 epilepsy seizures in the last 2 years. The aim was to treat decayed teeth and set good oral hygiene in the patient's mouth. Still, there is a probability for epilepsy seizures. If epileptic seizures stop permanently, we can apply an oral appliance to block tongue thrust. The patient is now under control. In cases of systemic and oral findings such as PKS, conducting medical and dental approaches together will increase the life quality of patients.

Ultrasonography reveals a high prevalence of lower spinal dysraphism in children with urogenital anomalies

BACKGROUND

Lower spinal dysraphism is frequently reported in anorectal anomaly combined with urogenital anomalies. The prevalence of the spinal dysraphism has not been comprehensively studied in children with simple urogenital anomalies. We evaluated the prevalence of the spinal dysraphism using ultrasound data of the lumbosacral area in children with urogenital anomalies.

METHODS

Lumbosacral ultrasound images of 259 children who underwent urological surgery with simple urogenital anomalies were reviewed by an ultrasound-specialized radiologist. The primary outcome measures were the conus medullaris (CM) level and the thickness of the filum terminale. The spinal ultrasonographic findings that were assessed in children showed abnormal spinal findings compared with the other children having normal findings. Two years later, the follow-up telephone interviews were made with the parents of the children with abnormal findings.

RESULTS

Eighteen children were differentiated as the abnormal finding group. They were suspected of spinal cord tethering. The level of CM was lower, and the filum terminale was thicker compared to the normal group [L2(lower (L)) vs. L1(L), 2.2 mm vs. 0.8 mm]. Of eighteen children, four were confirmed as tethered spinal cord with lipoma on magnetic resonance imaging by the time of surgery, and two were strongly suspected of occult spinal dysraphism (OSD) based on ultrasound findings and follow-up interviews.

CONCLUSIONS

The prevalence of OSD in children under 24 months of age with simple urogenital anomaly was higher than what was reported for the general population. Ultrasound examination of spinal structures before caudal block in children with urogenital anomaly should be considered.