Pallister-Killian syndrome: a study of 22 British patients

Pineocytoma in a child with Pallister-Killian syndrome: a case report and review of the literature

Pallister-Killian syndrome (PKS; OMIM #601803) is a rare genetic disorder typically characterized by developmental delay, seizures, sparse temporal hair, and facial dysmorphisms. PKS is most frequently caused by mosaic supernumerary isochromosome 12p. Here, we report a 27-month-old girl with a prenatal diagnosis of PKS and a histopathological diagnosis of pineocytoma.

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.

Testing With Intent in Mosaic Conditions: A Case-Based Review

Recent advancements in genetic testing have revealed cases of mosaicism, demonstrating the phenomenon may be more common than once thought. Broadly defined, mosaicism describes the presence of two genotypically different cell lineages within the same organism. This can arise from small mutations or errors in chromosome segregation, as early as in gametes, before or after fertilization. Mosaicism is directly responsible for many conditions that present in a wide range of tissues, with the presence of the mutation or genetic abnormality following a tissue-dependent pattern. This makes it possible for patients to test negative for a condition using a standard tissue sample while harboring the variant in a different tissue. Understanding the timing and mechanisms of mosaic conditions will aid in targeted testing that is more appropriate to identify a pathogenic variant. This targeted testing should reduce the length of a patient's diagnostic odyssey and provide a better understanding of the chances of passing on their variant to their offspring, thereby allowing for more accurate genetic counseling. We illustrate this phenomenon with two cases: one of Pallister-Killian syndrome and the other of tuberous sclerosis complex. Both patients had increased time to diagnosis because of difficulties in identifying genetic variants in tested tissues. Beyond just increased time to diagnosis, we illustrate that mosaic conditions can present as less severe and more variable than the germline condition and how specific germ layers may be affected by the variant. Knowing which germ layers may be affected by the variant can give clinicians a clue as to which tissues may need to be tested to yield the most accurate result.

Complexity in Genetic Epilepsies: A Comprehensive Review

Epilepsy is a highly prevalent neurological disorder, affecting between 5-8 per 1000 individuals and is associated with a lifetime risk of up to 3%. In addition to high incidence, epilepsy is a highly heterogeneous disorder, with variation including, but not limited to the following: severity, age of onset, type of seizure, developmental delay, drug responsiveness, and other comorbidities. Variable phenotypes are reflected in a range of etiologies including genetic, infectious, metabolic, immune, acquired/structural (resulting from, for example, a severe head injury or stroke), or idiopathic. This review will focus specifically on epilepsies with a genetic cause, genetic testing, and biomarkers in epilepsy.

Prenatal diagnosis of a case with complete and uniform tetrasomy 12p by the utility of noninvasive prenatal testing

PURPOSE

To report a rare type of Pallister-Killian syndrome (PKS) diagnosed prenatally by the utility of non-invasive prenatal testing (NIPT).

METHODS

NIPT was performed in the first trimester. Conventional karyotyping and chromosomal microarray analysis (CMA) were performed on the amniotic samples in the second trimester. Copy number variation sequencing (CNV-seq) was used for the validation of fetal skin and the placental tissue after pregnancy termination.

RESULTS

NIPT results showed increased signal from chromosome 12p. Subsequent prenatal diagnostic testing by karyotype revealed 47, XY, +i (12p), and CMA displayed four copies of 12p: 12p13.33-12p11.1(173786_34835641) × 4. The CNV-seq results of the fetal skin and the fetal side of placenta showed four copies of 12p13.33-p11 and an estimated chimeric duplication of 34.08 Mb (chimerism ratio: 10%) in 12 p13.33-p11, respectively. However, no abnormality was detected by CNV-seq at the maternal side of placenta.

CONCLUSIONS

Our findings suggest that a positive signal from chromosome 12p on NIPT should raise suspicion for PKS. With the wide application of NIPT, the true positive of incidental finding is expected to increase.

Extracorporeal Membrane Oxygenation (ECMO) for suspected neonatal genetic diagnoses with cardiorespiratory failure

Recent data describe an increasing use of extracorporeal membrane oxygenation (ECMO) in neonates with various clinical conditions besides primary respiratory or cardiac diagnoses. Infants with underlying genetic disorders characterized by cardiopulmonary failure pose unique management challenges. When pathognomonic dysmorphic features for common genetic diagnoses are not present, the prognosis is uncertain at best when determining ECMO candidacy. Lengthy turnaround times of genetic testing often delay definitive diagnosis during the ECMO course. Clinical management pathways to guide practice and evidence to support the use of ECMO in rare genetic conditions are lacking. The decision to initiate ECMO is daunting but may be of benefit if the subsequent genetic diagnosis is non-lethal. In lethal genetic cases warranting discontinuation of care, the time spent on ECMO may still be advantageous as a bridge to diagnosis while allowing for parental bonding with the terminally ill infant. Diagnostic confirmation may also facilitate the attainment of closure for these parents. Here, we report our experience providing ECMO to three neonates presenting with cardiorespiratory failure and later diagnosed with rare genetic syndromes. We share the challenges faced, lessons learned, and outcomes of these critically ill neonates.

Case Report: Early Neonatal EEG in Two Infants with Pallister Killian Syndrome (PKS)

Pallister Killian Syndrome (PKS) is a rare genetic disorder caused by a mosaic tetrasomy of the short arm of chromosome 12. The syndrome is characterised by typical craniofacial dysmorphism, congenital anomalies and intellectual disability. Epilepsy is a known complication, with onset usually occurring in early childhood and characterised most commonly by spasms and myoclonic seizures. To the best of our knowledge, there have been no cases describing the early neonatal EEG in PKS and  electrographic seizures, to date. Here, we report two cases of PKS presenting in the neonatal period with distinctive EEG features and seizures.

Cognitive, Behavioral, and Sensory Profile of Pallister–Killian Syndrome: A Prospective Study of 22 Individuals

Background: Developmental delay and intellectual disability are two pivotal elements of the phenotype of Pallister–Killian Syndrome (PKS). Our study aims to define the cognitive, adaptive, behavioral, and sensory profile of these patients and to evaluate possible correlations between the different aspects investigated and with the main clinical and demographic variables. Methods: Individuals of any age with genetically confirmed PKS were recruited. Those ≤ 42 months were administered the Bayley Scales of Infant and Toddler Development Third Edition (Bayley-III), and those > 42 months the Vineland Adaptive Behavior Scales—Second Edition (Vineland-II). Stereotyped behaviors (Stereotypy Severity Scale, SSS) and aggressive behaviors (Behavior Problems Inventory—Short Version, BPIs) were assessed in all subjects > 1 year; sensory profile (Child Sensory Profile 2, C-SP2) in all aged 2–18 years. Results: Twenty-two subjects were enrolled (11 F/11 M; age 9 months to 28 years). All subjects ≤ 42 months had psychomotor developmental delay. Of the subjects > 42 months, 15 had low IQ deviation, and 1 in the normal range. Stereotypies were frequent (median SSS-total score 25/68). Lower Vineland-II values corresponded to greater intensity and frequency of stereotypies (p = 0.004 and p = 0.003), and self-injurious behaviors (p = 0.002 and p = 0.002). Patients with severe low vision had greater interference of stereotypies (p = 0.027), and frequency and severity of aggressive behaviors (p = 0.026; p = 0.032). The C-SP2, while not homogeneous across subjects, showed prevalence of low registration and sensory seeking profiles and hypersensitivity to tactile and auditory stimuli. Lower Vineland-II scores correlated with higher Registration scores (p = 0.041), while stereotypies were more frequent and severe in case of high auditory sensitivity (p = 0.019; p = 0.007). Finally, greater sleep impairment correlated with stereotypies and self-injurious behaviors, and lower Vineland-II scores. Conclusions: The present study provides a further step in the investigation of the etiopathogenesis of the syndrome. Furthermore, these aspects could guide rehabilitation therapy through the identification of targeted protocols.

Case Report: A Case Study on the Neurodevelopmental Profile of a Child With Pallister-Killian Syndrome and His Unaffected Twin

Pallister-Killian syndrome is an uncommon genetic disorder that has broad developmental and multisystemic effects. While medical complications are widely reported throughout the literature, research on the neurodevelopmental profile has been limited. Case reports make up the majority of the few existing studies regarding the neurodevelopmental phenotype associated with this disorder. The current case report describes a 3-year-old male with Pallister-Killian syndrome (AF), reports the neurodevelopmental evaluation of his unaffected twin brother (MF), and outlines the results of an optical imaging study on both boys. AF presents with severe developmental delays, however, he ambulates with support and engages in conversation using his communication device. Most severely impaired was AF's speech and expressive language, with childhood apraxia of speech (CAS) as a possible explanation for these severe deficits. MF, the sibling, demonstrated neurotypical abilities and often advanced scores for his age. Both subjects completed a functional near-infrared spectroscopy (fNIRS) study, revealing decreased temporal and frontal lobe function in AF and typical functioning in MF. This case report expands on the existing literature on PKS by describing variances in fraternal twin presentation and novel reporting on fNIRS findings in both boys.

Sleep in Children With Pallister Killian Syndrome: A Prospective Clinical and Videopolysomnographic Study

Objectives: Pallister-Killian syndrome (PKS) is a rare genetic disorder with multi-organ involvement caused by mosaic tetrasomy of chromosome 12p. Although many caregivers report the presence of impaired sleep in their children, there are no clear data in the literature on this issue and no systematic study has ever been performed. With this study, we aimed to characterize the features of sleep in Pallister-Killian syndrome and identify the possible influence of clinical and demographic features. Moreover, our aim was to verify the effectiveness of conventional screening questionnaires in this particular group of patients.

Methods: We prospectively enrolled 14 patients aged 1–17 years in collaboration with PKS Kids Italia ONLUS. The Sleep Disturbance Scale for Children (SDSC) questionnaire was administered to caregivers. Then, video polysomnography (VPSG) of at least 24 h was performed and results were compared with a same-aged control group.

Results: A total of 92% of patients had abnormal SDSC scores, extremely high in the “disorder of initiating and maintaining sleep” (DIMS) and “sleep breathing disorders” (SBD) subscales. VPSG showed a significantly impaired macrostructure in PKS patients, with a higher Arousal Index (p < 0.00001) and percentage of time spent in N3 (p < 0.00001), and reduced Sleep Efficiency (p = 0.0006). After dividing both PKS and controls into two groups based on median age, some peculiarities emerged: the younger group had higher Awakenings Index (p = 0.0207) and percentage of time spent in N1 (p = 0.015) while the older group showed higher time in bed (TIB) (p = 0.0485), compared with controls. Due to poor compliance, the Apnea-Hypopnea Index (AHI) was evaluated only for 10 PKS children, being significantly increased (p = 0.0427) compared with controls. SBD subscale scores in SDSC were significantly related to AHI values in VPSG (p = 0.0099).

Conclusions: This study constitutes the first attempt to describe the sleep pattern in PKS. Despite small numbers due to the rarity of the syndrome, our VPSG results confirm the high prevalence of sleep disorders (SDs) in these patients. It is therefore essential to investigate and treat them. The SDSC scale is a good screening tool for early detection also in these patients, with particular sensitivity in detecting breathing disorders.

Prenatal diagnosis of Pallister-Killian syndrome and literature review

Pallister‐Killian syndrome (PKS) is a rare sporadic genetic disorder usually caused by mosaicism of an extra isochromosome of 12p (i(12p)). This retrospective study analysed the prenatal ultrasound manifestations and molecular and cytogenetic results of five PKS foetuses. Samples of amniotic fluid and/or cord blood, skin biopsy and placenta were collected. Conventional karyotyping and single nucleotide polymorphism array (SNP array) were performed on all the amniotic fluid or cord blood samples. Copy number variants sequencing (CNV‐seq) and fluorescence in situ hybridization (FISH) were also used for the validation for one foetus. All the five foetuses were from pregnancies with advanced parental age. Two foetuses involved structural abnormalities and one foetus had only soft markers, all of which included increased nuchal translucency. The rest two foetuses had normal ultrasounds in the second trimester, which has rarely been reported before. The karyotype revealed typical i(12p) in four cases and a small supernumerary marker chromosome consisting of 12p and 20p in the remaining one case. The proportion of cells with i(12p) ranged from 0 to 100% in cultural cells, while SNP array results suggested 2−4 copies of 12p. For one foetus, metaphase FISH showed normal results, but the interphase FISH suggested cell lines with two, three and four copies of 12p in the amniotic fluid. Advanced parental age may be an important risk factor for PKS, and there were no typical ultrasound manifestations related to PKS. A combination of karyotype analysis and molecular diagnosis is an effective method for the diagnosis of PKS.

HIST1H1E syndrome with type 2 diabetes

A 20-year-old woman was referred to the diabetes clinic with type 2 diabetes diagnosed at the age of 19. Her body mass index was 31.4 kg/m², HbA1C was 76 mmol/mol, GAD antibodies were negative with a detectable C-peptide. She had a characteristic facial appearance with widespread eyes, posterior hairline suggesting a facial gestalt and abnormal dentition. She also had hypothyroidism, mild intellectual disability, primary amenorrhoea and patent ductus arteriosus. Karyotyping reported normal 46XX karyotype. Genetic testing revealed a pathogenic variant in the gene encoding the HIST1H1E protein which confirmed her diagnosis of HIST1H1E syndrome. Type 2 diabetes has not been reported in previous cases of HIST1H1E and so this is the first reported case of type 2 diabetes with HIST1H1E syndrome.

Management of Congenital Diaphragmatic Hernia (CDH): Role of Molecular Genetics

Congenital diaphragmatic hernia (CDH) is a relatively common major life-threatening birth defect that results in significant mortality and morbidity depending primarily on lung hypoplasia, persistent pulmonary hypertension, and cardiac dysfunction. Despite its clinical relevance, CDH multifactorial etiology is still not completely understood. We reviewed current knowledge on normal diaphragm development and summarized genetic mutations and related pathways as well as cellular mechanisms involved in CDH. Our literature analysis showed that the discovery of harmful de novo variants in the fetus could constitute an important tool for the medical team during pregnancy, counselling, and childbirth. A better insight into the mechanisms regulating diaphragm development and genetic causes leading to CDH appeared essential to the development of new therapeutic strategies and evidence-based genetic counselling to parents. Integrated sequencing, development, and bioinformatics strategies could direct future functional studies on CDH; could be applied to cohorts and consortia for CDH and other birth defects; and could pave the way for potential therapies by providing molecular targets for drug discovery.

Pallister-Killian Syndrome versus Trisomy 12p-A Clinical Study of 5 New Cases and a Literature Review

Pallister–Killian syndrome (PKS) is a rare, sporadic disorder defined by a characteristic dysmorphic face, pigmentary skin anomalies, intellectual disability, hypotonia, and seizures caused by 12p tetrasomy due to an extra isochromosome 12p. We present three cases of PKS and two cases of trisomy 12p to illustrate and discuss features rarely cited in the literature, present certain particularities that not yet been cited, and analyze the differences between entities. Moreover, we present alternative methods of diagnosis that could be easily used in daily practice. Features not yet or rarely reported in PKS literature include marked excess of hair on the forehead and ears in the first months of life, a particular eye disorder (abnormal iris color with pointed pupil), connective tissue defects, repeated episodes of infection and autonomic dysfunction, endocrine malfunction as a possible cause of postnatal growth deficit, more complex sensory impairments, and mild early myoclonic jerks. After performing different combinations of tests, we conclude that MLPA (follow-up kit P230-B1) or array CGH using DNA extracted from a buccal swab is a reliable method of diagnosis in PKS and we recommend either one as a first intention diagnostic test. In cases without major defects associated (suspicion trisomy 12p), subtelomeric MLPA should be performed first.

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.

A Novel Case of Tethered Cord in a Five-Month-Old Male With Pallister-Killian Syndrome

A five-month-old male presented with an incidentally found low-lying conus medullaris on ultrasound and subsequent MRI demonstrating its position at L4. Pre-operative examination findings included mild, global hypotonia and a coccygeal dimple without bladder or bowel abnormalities or spasticity. The patient underwent spinal cord untethering with a section of filum terminale and was discharged without complication following his procedure. Follow-up at one year revealed continued baseline hypotonia without further neurosurgical needs. This is the first reported case of tethered cord syndrome described in a patient with Pallister-Killian syndrome managed successfully with neurosurgical intervention.

Seizures and Cardiomyopathy in a Patient with Pallister-Killian Syndrome due to Hexasomy 12p Mosaicism

Pallister-Killian syndrome (PKS) is a rare disorder presenting with developmental delay, numerous dysmorphic features, and skin pigmentation anomalies. It is caused by mosaic tetrasomy of the short arm of chromosome 12. In most instances, tetrasomy is due to a supernumerary isochromosome i(12)(p10). Although mitotic instability is a generally accepted behavior for supernumerary chromosomes, hexasomy 12p due to a gain of an isochromosome 12p, has been hardly ever reported. We report a 10 year follow-up on a girl with 2 copies of isochromosome consisting of the short arm of chromosome 12, who has craniofacial features seen in PKS, such as sparse hair with an unusual pattern, sparse eyebrows, lacrimal duct stenosis, submucous cleft palate, Pallister lip (a relatively long philtrum continuing into the vermillion border of the upper lip), narrow palate, and wide alveolar ridges. She also has other abnormalities, including unilateral renal dysgenesis, rectovaginal fistula, pre-axial polydactyly of the right hand, severe global developmental delay, and hypotonia as well as some features suggestive of mosaicism such as bilateral asymmetry, patchy areas of rough skin, and retinal mottling. Initial cytogenetic studies from peripheral blood showed a normal female karyotype. Further cytogenetic studies on a skin biopsy showed mosaicism with 2 copies of the supernumerary isochromosome 12p.

Postnatal clinical phenotype of five patients with Pallister-Killian Syndrome (tetrasomy 12p): Interest of array CGH for diagnosis and review of the literature

Background

Pallister–Killian syndrome (PKS) is a rare sporadic disorder caused by tetrasomy of the short arm of chromosome 12. The main clinical manifestations are global developmental delay, intellectual disability, epilepsy, dysmorphic features, hypopigmented and/or hyperpigmented lesions, and multiple congenital anomalies. PKS is associated with tissue mosaicism, which is difficult to diagnose through peripheral blood sample by conventional cytogenetic methods and fluorescence in situ hybridization.

Methods

Here, we report five patients with PKS. We delineate their clinical phenotypes and we compare them with previously published cases. We used array Comparative Genomic Hybridization (aCGH) with DNA extracted from peripheral blood samples. The five patients have also been tested by conventional cytogenetics techniques.

Results

Four out of five patients showed tetrasomy 12p by aCGH. Three of the four patients have typical i(12p) and one of the four demonstrated atypical tetrasomy 12p. The percentage of mosaicism was as low as 20%. Our cohort exhibited the typical PKS phenotypes.

Conclusion

Our results demonstrate the efficacy of aCGH for the diagnosis of PKS from DNA extracted from lymphocytes. Thus, for patients suspected of PKS, we recommend performing aCGH on lymphocytes at an early age before  proceeding to skin biopsy. aCGH on peripheral blood samples is sensitive in detecting low level of mosaicism and it is less invasive method than skin biopsy. We reviewed also the literature concerning the previously published PKS patients diagnosed by aCGH.

Ductus Venosus Agenesis as a Marker of Pallister-Killian Syndrome

The ductus venosus (DV) is a shunt that allows the direct flow of well-oxygenated blood from the umbilical vein (UV) to the coronary and cerebral circulation through the foramen ovale. Its agenesis has been associated with chromosomal abnormalities and rare genetic syndromes, structural defects, intrauterine growth restriction (IUGR) and even antepartum fetal demise. Pallister–Killian Syndrome (PKS) is a rare sporadic disorder with specific tissue mosaic distribution of an extra 12p isochromosome (i(12p)). Its main clinical features are moderate to severe intellectual disability/neuromotor delay, skin pigmentation abnormalities, typical facial appearance, variable association with multiple congenital malformations and epilepsy. Though prenatal findings (including congenital diaphragmatic hernia, ventriculomegaly, congenital heart disease, polyhydramnios, and rhizomelic shortening) have been described in literature, prenatal diagnosis is difficult as there are no associated identification signs no distinctive or pathognomonic signs, and some of these malformations are hard to identify prenatally. The tissue mosaicism linked to this syndrome and the decrease of the abnormal clone carrier of the i(p12) after successive trypsinizations of cultured cells makes the diagnosis even more challenging. We present the case of a 27.5 weeks pregnant woman with a fetal ductus venosus agenesis (DVA) as the main guide marker. To our knowledge this is the first case published in literature reporting a DVA as a guide sign to diagnose a complex condition as Pallister–Killian syndrome. We also underscore the key role of new genetic techniques as microarrays to avoid misdiagnosis when only a subtle sonographic sign is present in complex conditions like this.

Myoclonic epilepsy with photosensitivity in infants with Pallister-Killian Syndrome

INTRODUCTION

Pallister-Killian Syndrome (PKS) (OMIM #601803) is a rare genetic disorder caused by a mosaic tetrasomy of the short arm of chromosome 12. Epilepsy is a frequent concern in PKS patients.

METHODS

we report 3 PKS patients, with early-onset myoclonic epilepsy and photosensitivity. In these children, we analysed epileptic history and the EEG phenotype.

RESULTS

Epilepsy onset was in the first 2 years of life in all patients and in 2 of them myoclonic seizures were the only seizure type. In all children photosensitivity was observed and myoclonic seizures were mainly related to low-frequency (1-6 Hz) intermittent photic stimulation. Levetiracetam was effective and well tolerated in the 2 treated patients.

CONCLUSIONS

early-onset myoclonic epilepsy is a possible clinical manifestation of PKS. Low-frequency photosensitivity is a peculiar bioelectrical marker in these children.

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.

Pseudoacromegaly

Individuals with acromegaloid physical appearance or tall stature may be referred to endocrinologists to exclude growth hormone (GH) excess. While some of these subjects could be healthy individuals with normal variants of growth or physical traits, others will have acromegaly or pituitary gigantism, which are, in general, straightforward diagnoses upon assessment of the GH/IGF-1 axis. However, some patients with physical features resembling acromegaly - usually affecting the face and extremities -, or gigantism - accelerated growth/tall stature - will have no abnormalities in the GH axis. This scenario is termed pseudoacromegaly, and its correct diagnosis can be challenging due to the rarity and variability of these conditions, as well as due to significant overlap in their characteristics. In this review we aim to provide a comprehensive overview of pseudoacromegaly conditions, highlighting their similarities and differences with acromegaly and pituitary gigantism, to aid physicians with the diagnosis of patients with pseudoacromegaly.

Small supernumerary marker chromosomes: A legacy of trisomy rescue?

We studied by a whole genomic approach and trios genotyping, 12 de novo, nonrecurrent small supernumerary marker chromosomes (sSMC), detected as mosaics during pre- or postnatal diagnosis and associated with increased maternal age. Four sSMCs contained pericentromeric portions only, whereas eight had additional non-contiguous portions of the same chromosome, assembled together in a disordered fashion by repair-based mechanisms in a chromothriptic event. Maternal hetero/isodisomy was detected with a paternal origin of the sSMC in some cases, whereas in others two maternal alleles in the sSMC region and biparental haplotypes of the homologs were detected. In other cases, the homologs were biparental while the sSMC had the same haplotype of the maternally inherited chromosome. These findings strongly suggest that most sSMCs are the result of a multiple-step mechanism, initiated by maternal meiotic nondisjunction followed by postzygotic anaphase lagging of the supernumerary chromosome and its subsequent chromothripsis.

Pallister-Killian syndrome: clinical, cytogenetic and molecular findings in 15 cases

Background

Pallister Killian syndrome (PKS, OMIM 601803) is a rare genetic disorder with a distinct phenotype caused by tissue- limited mosaicism tetrasomy of the short arm of chromosome 12, which usually cytogenetically presents as an extra isochromosome 12p.Wide phenotypic variability in PKS has been reported, ranging from pre-to perinatal death due to multiple congenital anomalies, especially diaphragmatic hernia, and classic phenotypes including seizures, severe developmental delay, macrosomia at birth, deafness, and distinct dysmorphic features, such as coarse face, temporal alopecia, a small nose with anteverted nostrils, long philtrum, and hypo-/hyper- pigmented streaks on the skin.

Results

Karyotypes obtained from cultured peripheral lymphocytes of 13 cases, who were diagnosed as PKS, were normal, while karyotypes obtained from cultured skin samples and buccal mucosa revealed the supernumerary mosaic i(12p). Mosaic karyotype was found in both fibroblast and buccal mucosa in 14 of 15 patients in our series, whereas in one stillbirth, following the clinical diagnosis of PKS, skin and buccal smear samples were taken, and all karyotypes from cultured fibroblasts revealed a supernumerary i(12p), while I-FISH study showed 60% mosaicism in mucosal cells.

Conclusions

We here share the clinical, cytogenetic and molecular cytogenetic findings of 15 cases with PKS phenotype and the parental origin of seven i(12p) identified by molecular analyses. To our knowledge, this is the largest series of PKS patients with parental origin study from a single center. We believe that our study makes a significant contribution to the literature because we specifically found no differences in the phenotypes of cases with either a maternal or paternal origin of the extra element and differential imprinting appeared not to be a factor.

Epilepsy genetics: Current knowledge, applications, and future directions

The rapid pace of disease gene discovery has resulted in tremendous advances in the field of epilepsy genetics. Clinical testing with comprehensive gene panels, exomes, and genomes are now available and have led to higher diagnostic rates and insights into the underlying disease processes. As such, the contribution to the care of patients by medical geneticists, neurogeneticists and genetic counselors are significant; the dysmorphic examination, the necessary pre- and post-test counseling, the selection of the appropriate next-generation sequencing-based test(s), and the interpretation of sequencing results require a care provider to have a comprehensive working knowledge of the strengths and limitations of the available testing technologies. As the underlying mechanisms of the encephalopathies and epilepsies are better understood, there may be opportunities for the development of novel therapies based on an individual's own specific genotype. Drug screening with in vitro and in vivo models of epilepsy can potentially facilitate new treatment strategies. The future of epilepsy genetics will also probably include other-omic approaches such as transcriptomes, metabolomes, and the expanded use of whole genome sequencing to further improve our understanding of epilepsy and provide better care for those with the disease.

The Occurrence of 275 Rare Diseases and 47 Rare Disease Groups in Italy. Results from the National Registry of Rare Diseases

Knowledge of rare diseases (RD) is often scattered among many data collections and registries of patient cohorts. Therefore, assessing the burden of RD in the general population, developing appropriate policies and planning services for the care of RD patients is difficult. This study aimed at providing a systematic picture of RD occurrence in a population as big as 60 million. Data of diagnoses were certified and collected by a network of 247 specialized centres covering the whole Italian territory. Data received (about 200,000 records) were validated according to formal criteria and, where necessary, corrected by the data sources. Data of age at onset and sex distribution are given for about 400 diseases. Incidence and/or birth prevalence are given for 275 diseases and 47 disease groups, which, altogether, comprise a substantial part of the known rare diseases. Data quality, internal consistency, and external validity of the database have also been assessed and ways to limit the impact of some discrepancies were devised. The information provided by RNMR, cutting across such a wide range of RD, represents a unique coherent basis allowing the prioritization of relevant public health measures and research activities.

Pallister-Killian syndrome: Review of fetal phenotype

Pallister-Killian syndrome is a multi-system sporadic disorder with developmental delay. It is a rare chromosomal abnormality involving supernumerary isochormosome 12p. The disorder exhibits tissue specific mosaicism. The first prenatal diagnosis of PKS was reported in 1985 after ultrasound detection of fetal anomalies. Since this observation, there have been about 62 reports of fetuses with PKS. In this review, we cover the prenatal aspects of PKS.

Progressive subglottic stenosis in a child with Pallister-Killian syndrome

Pallister-Killian syndrome (PKS) is rare genetic disorder caused by tetrasomy 12p mosaicism with supernumerary isochromosome 12p that manifests with intellectual disability, craniofacial dysmorphism, and epilepsy. Although PKS presents as a multisystem morphological defect, respiratory system involvement is rare, except for diaphragmatic hernia. We are the first to report a case of PKS with progressive subglottic stenosis. Subglottic stenosis is a potentially lethal condition due to severe respiratory obstruction and difficult intubation; therefore, further accumulation of cases is required to assess the causal link between PKS and subglottic stenosis.

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.

Male fertility and skin diseases

Male fertility can be affected by a variety of organs diseases, including the skin. Several genodermatoses affect the skin and several other organs including the male reproductive system, commonly in the form of cryptorchidism and hypogonadism. The most relevant syndromes are associated with dyschromias, such as deSanctis-Cacchione, poikiloderma congenital, LEOPARD, and H syndrome; others with ichthyosis, such as Rud, and trichothiodystrophy; or a group of unrelated genodermatoses, such as ablepharon macrostomia, Coffin-Siris, Gorlin-Goltz, and Werner. Acquired skin diseases may also affect male fertility usually in the form of orchitis or epididymal obstruction or androgen antagonists. These include infections (leprosy and HIV), autoimmune (erythema nodosum leprosum), granulomatous (sarcoidosis, Langerhans cell histiocytosis), nutritional deficiency (zinc), and malignancy. Several therapeutics of skin diseases are notorious for their effects on male fertility, most notably are the cytotoxic drugs (methotrexate), irradiation, and antiandrogens (spironolactone, finasteride). Although the prevalence of these skin diseases is low, the associated male infertility represents a challenge due to the difficulty of its management. Clinical management of the skin diseases should include consideration of their effects not only on the diseases but also on the male reproductive system.

Oro-dental features of Pallister-Killian syndrome: Evaluation of 21 European probands

Pallister-Killian syndrome (PKS) is a rare sporadic multi-systemic developmental disorder caused by a mosaic tetrasomy of the short arm of chromosome 12. A wide range of clinical characteristics including intellectual disability, seizures, and congenital malformations has previously been described. Individuals with PKS show a characteristic facial phenotype with frontal bossing, alopecia, sparse eyebrows, depressed nasal bridge, long philtrum, telecanthus, and posteriorly rotated ears. Oro-dental features, such as "Pallister lip," macroglossia, delayed eruption of primary teeth, high arched-palate, prognathism, and cleft palate have been occasionally reported in the medical literature. The aim of the study was to assess the oro-dental phenotype of PKS and to describe the oral health status in a cohort participating in the First European Workshop on PKS. A clinical dental examination was performed in 21 Caucasian probands and data regarding medical and dental history collected. Twelve probands (57%) showed an atypical dental pattern, with multiple missing teeth (primarily the first permanent molars) and 2 (10%) a double teeth. The severity of gingivitis and dental caries increased with age and gingival overgrowth was a common finding. A characteristic occlusive phenotype was found: a high-arched palate with mandibular prognathism associated with an anterior openbite and crossbite and with posterior crossbite (unilateral or bilateral). The prevalence of oral habits (non-nutritive sucking, mouth breathing, bruxism) was high, even in older probands. This study suggests that individuals affected by PKS should be observed closely for oro-dental diseases and a multidisciplinary approach is needed to implement the right preventive measures. © 2016 Wiley Periodicals, Inc.

[Prenatal and clinicopathological study of 6 cases of Pallister-Killian syndrome and review]

OBJECTIVE

In multidisciplinary prenatal diagnosis centers, the search for a tetrasomy 12p mosaic is requested following the discovery of a diaphragmatic hernia in the antenatal period. Thus, the series of Pallister Killian syndromes (PKS: OMIM 601803) probably overestimate the prevalence of diaphragmatic hernia in this syndrome to the detriment of other morphological abnormalities.

METHODS

A multicenter retrospective study was conducted with search for assistance from members of the French society for Fetal Pathology. For each identified case, we collected all antenatal and postnatal data. Antenatal data were compared with data from the clinicopathological examination to assess the adequacy of sonographic signs of PKS. A review of the literature on antenatal morphological anomalies in case of PKS completed the study.

RESULTS

Ten cases were referred to us: 7 had cytogenetic confirmation and 6 had ultrasound screening. In the prenatal as well as post mortem period, the most common sign is facial dysmorphism (5 cases/6). A malformation of limbs is reported in half of the cases (3 out of 6). Ultrasound examination detected craniofacial dysmorphism in 5 cases out of 6. We found 1 case of left diaphragmatic hernia. Our results are in agreement with the malformation spectrum described in the literature.

CONCLUSION

Some malformation associations could evoke a SPK without classical diaphragmatic hernia.