Searching for Potocki-Lupski syndrome phenotype: a patient with language impairment and no autism

Dental findings and intravenous sedation in a patient with Potocki-Lupski syndrome: A case report

AIMS

Potocki-Lupski syndrome (PTLS), which is caused by the partial duplication of the short arm of autosome 17, is characterized by feeding difficulties associated with muscle hypotonia and dysphagia in infancy, followed by growth retardation and low body weight in later stages. Speech and motor developmental disorders are observed in childhood, accompanied by autism spectrum disorders in several cases. Other disorders include dental and skeletal abnormalities, and associated sleep apnea. Herein, we describe the first case of dental evaluation and treatment under intravenous sedation in a patient with PTLS.

METHODS

A 13-year-old boy with PTLS and intellectual disability was referred for the treatment of dental caries. Routine intraoral examination and dental treatment were not feasible. As the patient had no muscle hypotonia, dysphagia, or severe growth delay, intraoral examination and dental treatment were successfully performed under intravenous sedation. No incidence of intraoral airway obstruction or aspiration was reported. The patient was followed-up post-operatively.

CONCLUSION

PTLS, a newly identified syndrome, is associated with cardiovascular abnormalities, dysphagia, failure to thrive, and sleep apnea, which are potential risk factors for sedation. This case report highlights the importance of facial and oral findings in determining the risks of difficulties in airway management.

Does the Potocki–Lupski Syndrome Convey the Autism Spectrum Disorder Phenotype? Case Report and Scoping Review

Potocki–Lupski Syndrome (PTLS) is a rare condition associated with a duplication of 17p11.2 that may underlie a wide range of congenital abnormalities and heterogeneous behavioral phenotypes. Along with developmental delay and intellectual disability, autism-specific traits are often reported to be the most common among patients with PTLS. To contribute to the discussion of the role of autism spectrum disorder (ASD) in the PTLS phenotype, we present a case of a female adolescent with a de novo dup(17) (p11.2p11.2) without ASD features, focusing on in-depth clinical, behavioral, and electrophysiological (EEG) evaluations. Among EEG features, we found the atypical peak–slow wave patterns and a unique saw-like sharp wave of 13 Hz that was not previously described in any other patient. The power spectral density of the resting state EEG was typical in our patient with only the values of non-linear EEG dynamics: Hjorth complexity and fractal dimension were drastically attenuated compared with the patient’s neurotypical peers. Here we also summarize results from previously published reports of PTLS that point to the approximately 21% occurrence of ASD in PTLS that might be biased, taking into account methodological limitations. More consistent among PTLS patients were intellectual disability and speech and language disorders.

A New Patient with Potocki-Lupski Syndrome: A Literature Review

Speech delay, intellectual disability, and behavioral disturbances are the main clinical manifestations of Potocki-Lupski syndrome. Other features include infantile hypotonia, the absence of major dysmorphism, sleep disorders, and congenital anomalies, particularly of the cardiovascular system. A male patient with Potocki-Lupski syndrome is reported herein. He showed speech and borderline cognitive delay, behavioral troubles with no signs suggestive of autism, in the absence of major dysmorphism. A de novo 17p12-p11.2 duplication spanning 3.6 Mb was detected, with boundaries from 15,284,052 to 18,647,233 (hg19 assembly). At the age of 5 years, the child showed a noticeable improvement of speech skills and a moderate scholastic performance was reached. Upon analysis of the clinical manifestations of the present patient and those reported in existing literature, we found that the syndrome may present in various degrees of clinical expressivity. Affected patients may manifest symptoms ranging from mild behavioral disturbances to severe degrees of autism.

RAI1 Overexpression Promotes Altered Circadian Gene Expression and Dyssomnia in Potocki-Lupski Syndrome

Retinoic acid induced 1 ( RAI1 ) encodes a dosage-sensitive gene that when haploinsufficient results in Smith-Magenis syndrome (SMS) and when overexpressed results in Potocki-Lupski syndrome (PTLS). Phenotypic and molecular evidence illustrates that haploinsufficiency of RAI1 disrupts circadian rhythm through the dysregulation of the master circadian regulator, circadian locomotor output cycles kaput ( CLOCK) , and other core circadian components, contributing to prominent sleep disturbances in SMS. However, the phenotypic and molecular characterization of sleep features in PTLS has not been elucidated. Using the Pittsburgh Sleep Quality Index (PSQI), caregivers of 15 school-aged children with PTLS reported difficulties in initiating sleep. Indeed, more than 70% of individuals manifested moderate to severe sleep latency, as defined by the PSQI. Moreover, these individuals manifested difficulties in sleep maintenance, with middle of the night and early morning awakenings. When assessing daytime sleepiness through the Epworth Sleepiness Scale, approximately 21% of the individuals manifested excessive daytime somnolence. This indicates that mild dyssomnia characterizes the majority of the sleep phenotype, with occasionally problematic daytime somnolence, a phenotype different than that expressed by individuals with SMS, where daytime sleepiness is a chronic problem. Gene expression analysis of the core circadian machinery in the hypothalamus of the PTLS mouse model ( Rai1 -Tg) found significant dysregulation of the transcriptional activators, Clock and Arntl , and the transcriptional repressors, Per1-3 and Cry1/2 , during both light and dark phases. These findings suggest a partial loss of circadian entrainment typically evoked by environmental photic cues. Examination of circadian clock gene expression in the Rai1- Tg mouse heart, liver, and kidney found unchanged expression of Clock and most of its downstream targets during both light and dark phases, suggesting an asynchronized circadian rhythm. Furthermore, examination of circadian gene expression in synchronized PTLS lymphoblasts revealed reduced transcripts of the Period ( PER1-3 ) family and normal expression of CRY1/2 . The finding that central circadian gene expression was altered while many peripheral circadian components were intact suggests a tissue-specific circadian uncoupling of the circadian machinery due to Rai1 overexpression. Overall, our results demonstrate that overexpression of RAI1 results in sleep deficiencies in individuals with PTLS due to a lack of properly regulated circadian machinery gene expression and highlight the importance of evaluating sleep concerns in individuals with PTLS.

Neurodevelopmental Disorders Associated with Abnormal Gene Dosage: Smith-Magenis and Potocki-Lupski Syndromes

Smith-Magenis syndrome (SMS) and Potocki-Lupski syndrome (PTLS) are reciprocal contiguous gene syndromes within the well-characterized 17p11.2 region. Approximately 3.6 Mb microduplication of 17p11.2, known as PTLS, represents the mechanistically predicted homologous recombination reciprocal of the SMS microdeletion, both resulting in multiple congenital anomalies. Mouse model studies have revealed that the retinoic acid-inducible 1 gene (RAI1) within the SMS and PTLS critical genomic interval is the dosage-sensitive gene responsible for the major phenotypic features in these disorders. Even though PTLS and SMS share the same genomic region, clinical manifestations and behavioral issues are distinct and in fact some mirror traits may be on opposite ends of a given phenotypic spectrum. We describe the neurobehavioral phenotypes of SMS and PTLS patients during different life phases as well as clinical guidelines for diagnosis and a multidisciplinary approach once diagnosis is confirmed by array comparative genomic hybridization or RAI1 gene sequencing. The main goal is to increase awareness of these rare disorders because an earlier diagnosis will lead to more timely developmental intervention and medical management which will improve clinical outcome.

Clinical and cytogenetic features of a Potocki-Lupski syndrome with the shortest 0.25Mb microduplication in 17p11.2 including RAI1

Potocki-Lupski syndrome (PTLS [MIM 610883]) is a recently recognized microduplication syndrome associated with 17p11.2. It is characterized by mild facial dysmorphic features, hypermetropia, infantile hypotonia, failure to thrive, mental retardation, autistic spectrum disorders, behavioral abnormalities, sleep apnea, and cardiovascular anomalies. In several studies, the critical PTLS region was deduced to be 1.3Mb in length, and included RAI1 and 17 other genes. We report a 3-year-old Korean boy with the smallest duplication in 17p11.2 and a milder phenotype. He had no family history of neurologic disease or developmental delay and no history of seizure, autistic features, or behavior problems. He showed subtle facial dysmorphic features (dolichocephaly and a mildly asymmetric smile) and flat feet. All laboratory tests were normal and he had no evidence of internal organ anomalies. He was found to have mild intellectual disabilities (full scale IQ 65 on K-WPPSI) and language developmental delay (age of 2.2year-old on PRESS). Array comparative genomic hybridization (CGH) showed about a 0.25Mb microduplication on chromosome 17p11.2 containing four Refseq (NCBI reference sequence) genes, including RAI1 [arr 17p11.2(17,575,978-17,824,623)×3]. When compared with previously reported cases, the milder phenotype of our patient may be associated with the smallest duplication in 17p11.2, 0.25Mb in length.

Genetic insights into the functional elements of language

Language disorders cover a wide range of conditions with heterologous and overlapping phenotypes and complex etiologies harboring both genetic and environmental influences. Genetic approaches including the identification of genes linked to speech and language phenotypes and the characterization of normal and aberrant functions of these genes have, in recent years, unraveled complex details of molecular and cognitive mechanisms and provided valuable insight into the biological foundations of language. Consistent with this approach, we have reviewed the functional aspects of allelic variants of genes which are currently known to be either causally associated with disorders of speech and language or impact upon the spectrum of normal language ability. We have also reviewed candidate genes associated with heritable speech and language disorders. In addition, we have evaluated language phenotypes and associated genetic components in developmental syndromes that, together with a spectrum of altered language abilities, manifest various phenotypes and offer details of multifactorial determinants of language function. Data from this review have revealed a predominance of regulatory networks involved in the control of differentiation and functioning of neurons, neuronal tracks and connections among brain structures associated with both cognitive and language faculties. Our findings, furthermore, have highlighted several multifactorial determinants in overlapping speech and language phenotypes. Collectively this analysis has revealed an interconnected developmental network and a close association of the language faculty with cognitive functions, a finding that has the potential to provide insight into linguistic hypotheses defining in particular, the contribution of genetic elements to and the modular nature of the language faculty.

Opposing phenotypes in mice with Smith-Magenis deletion and Potocki-Lupski duplication syndromes suggest gene dosage effects on fluid consumption behavior

A quantitative long-term fluid consumption and fluid-licking assay was performed in two mouse models with either an ∼2 Mb genomic deletion, Df(11)17, or the reciprocal duplication copy number variation (CNV), Dp(11)17, analogous to the human genomic rearrangements causing either Smith-Magenis syndrome [SMS; OMIM #182290] or Potocki-Lupski syndrome [PTLS; OMIM #610883], respectively. Both mouse strains display distinct quantitative alterations in fluid consumption compared to their wild-type littermates; several of these changes are diametrically opposing between the two chromosome engineered mouse models. Mice with duplication versus deletion showed longer versus shorter intervals between visits to the waterspout, generated more versus less licks per visit and had higher versus lower variability in the number of licks per lick-burst as compared to their respective wild-type littermates. These findings suggest that copy number variation can affect long-term fluid consumption behavior in mice. Other behavioral differences were unique for either the duplication or deletion mutants; the deletion CNV resulted in increased variability of the licking rhythm, and the duplication CNV resulted in a significant slowing of the licking rhythm. Our findings document a readily quantitated complex behavioral response that can be directly and reciprocally influenced by a gene dosage effect.