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Roy SM, Rafferty D, Trejo A, Hamilton L, Bohonowych JE, Strong TV, Ambartsumyan L, Cantu S, Scheimann A, Duis J. Feeding tube use and complications in Prader-Willi syndrome: Data from the Global Prader-Willi Syndrome Registry. Am J Med Genet A 2024; 194:e63546. [PMID: 38303141 DOI: 10.1002/ajmg.a.63546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 01/11/2024] [Accepted: 01/15/2024] [Indexed: 02/03/2024]
Abstract
Guidance on indications for, and types of, feeding tubes recommended in Prader-Willi syndrome (PWS) is needed. A Global PWS Registry survey was developed to investigate nasogastric (NG) and gastrostomy (G) tube use and associated complications. Of 346 participants, 242 (69.9%) had NG-tubes, 17 (4.9%) had G-tubes, and 87 (25.1%) had both NG- and G-tubes. Primary indication for placement was "feeding difficulties and/or poor weight gain" for both NG- (90.2%) and G-tubes (71.2%), while "aspiration/breathing difficulties" was the procedural indication for 6.4% of NG-tubes and 23.1% of G-tubes. NG-tubes were generally removed by age 6 months (NG Only: 82.9%; NG/G: 98.8%), while G-tubes were often removed by age 2 years (G Only: 85.7%; NG/G: 70.5%). The severe complication rate from G-tubes was 31.7% and from NG-tubes was 1.2%. Overall, caregivers indicated the presence of an NG- or G-tube had a positive effect on quality of life. Feeding difficulties in PWS are largely managed by NG-tube alone. The severe complication rate from G-tubes was about 25 times higher than from NG-tubes; yet, G-tube placement rates have generally increased. G-tube placement puts individuals with PWS at risk for anesthesia and surgery-related complications and should be considered judiciously by a multidisciplinary team.
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Affiliation(s)
- Sani M Roy
- Cook Children's Medical Center, Fort Worth, Texas, USA
| | | | - Amy Trejo
- Cook Children's Medical Center, Fort Worth, Texas, USA
| | - Luke Hamilton
- Cook Children's Medical Center, Fort Worth, Texas, USA
| | | | | | | | - Samson Cantu
- Cook Children's Medical Center, Fort Worth, Texas, USA
| | - Ann Scheimann
- The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Texas Children's Hospital, Houston, Texas, USA
| | - Jessica Duis
- Children's Hospital Colorado, Aurora, Colorado, USA
- SequenceMD, Denver, Colorado, USA
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2
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Madeo SF, Zagaroli L, Vandelli S, Calcaterra V, Crinò A, De Sanctis L, Faienza MF, Fintini D, Guazzarotti L, Licenziati MR, Mozzillo E, Pajno R, Scarano E, Street ME, Wasniewska M, Bocchini S, Bucolo C, Buganza R, Chiarito M, Corica D, Di Candia F, Francavilla R, Fratangeli N, Improda N, Morabito LA, Mozzato C, Rossi V, Schiavariello C, Farello G, Iughetti L, Salpietro V, Salvatoni A, Giordano M, Grugni G, Delvecchio M. Endocrine features of Prader-Willi syndrome: a narrative review focusing on genotype-phenotype correlation. Front Endocrinol (Lausanne) 2024; 15:1382583. [PMID: 38737552 PMCID: PMC11082343 DOI: 10.3389/fendo.2024.1382583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 04/12/2024] [Indexed: 05/14/2024] Open
Abstract
Prader-Willi syndrome (PWS) is a complex genetic disorder caused by three different types of molecular genetic abnormalities. The most common defect is a deletion on the paternal 15q11-q13 chromosome, which is seen in about 60% of individuals. The next most common abnormality is maternal disomy 15, found in around 35% of cases, and a defect in the imprinting center that controls the activity of certain genes on chromosome 15, seen in 1-3% of cases. Individuals with PWS typically experience issues with the hypothalamic-pituitary axis, leading to excessive hunger (hyperphagia), severe obesity, various endocrine disorders, and intellectual disability. Differences in physical and behavioral characteristics between patients with PWS due to deletion versus those with maternal disomy are discussed in literature. Patients with maternal disomy tend to have more frequent neurodevelopmental problems, such as autistic traits and behavioral issues, and generally have higher IQ levels compared to those with deletion of the critical PWS region. This has led us to review the pertinent literature to investigate the possibility of establishing connections between the genetic abnormalities and the endocrine disorders experienced by PWS patients, in order to develop more targeted diagnostic and treatment protocols. In this review, we will review the current state of clinical studies focusing on endocrine disorders in individuals with PWS patients, with a specific focus on the various genetic causes. We will look at topics such as neonatal anthropometry, thyroid issues, adrenal problems, hypogonadism, bone metabolism abnormalities, metabolic syndrome resulting from severe obesity caused by hyperphagia, deficiencies in the GH/IGF-1 axis, and the corresponding responses to treatment.
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Affiliation(s)
- Simona F. Madeo
- Department of Medical and Surgical Sciences for Mother, Children and Adults, Pediatric Unit, University of Modena and Reggio Emilia, Modena, Italy
| | - Luca Zagaroli
- Department of Pediatrics, University of L’Aquila, L’Aquila, Italy
| | - Sara Vandelli
- Department of Medical and Surgical Sciences for Mother, Children and Adults, Post-Graduate School of Pediatrics, University of Modena and Reggio Emilia, Modena, Italy
| | - Valeria Calcaterra
- Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy
- Pediatric Department, Buzzi Children’s Hospital, Milano, Italy
| | - Antonino Crinò
- Center for Rare Diseases and Congenital Defects, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Luisa De Sanctis
- Pediatric Endocrinology, Regina Margherita Children Hospital – Department of Public Health and Pediatric Sciences, University of Torino, Torino, Italy
| | - Maria Felicia Faienza
- Pediatric Unit, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari “Aldo Moro”, Bari, Italy
| | - Danilo Fintini
- Prader Willi Reference Center, Endocrinology and Diabetology Unit, Pediatric University Department, IRCCS Bambino Gesù Children Hospital, Rome, Italy
| | - Laura Guazzarotti
- Pediatric Endocrinology Unit, University Hospital of Padova, Padova, Italy
| | - Maria Rosaria Licenziati
- Neuro-endocrine Diseases and Obesity Unit, Department of Neurosciences, Santobono-Pausilipon Children’s Hospital, Naples, Italy
| | - Enza Mozzillo
- Department of Translational and Medical Science, Section of Pediatrics, University of Naples Federico II, Naples, Italy
| | - Roberta Pajno
- Pediatric Unit, IRCCS San Raffaele Institute, Milan, Italy
| | - Emanuela Scarano
- Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Maria E. Street
- Department of Medicine and Surgery, University of Parma, Parma, Italy
- Department of Medicine and Surgery, University Hospital of Parma, Parma, Italy
| | - Malgorzata Wasniewska
- Department of Human Pathology of Adulthood and Childhood, University of Messina, Messina, Italy
- Pediatric Unit, Gaetano Martino University Hospital of Messina, Messina, Italy
| | - Sarah Bocchini
- Prader Willi Reference Center, Endocrinology and Diabetology Unit, Pediatric University Department, IRCCS Bambino Gesù Children Hospital, Rome, Italy
| | - Carmen Bucolo
- Pediatric Unit, IRCCS San Raffaele Institute, Milan, Italy
| | - Raffaele Buganza
- Pediatric Endocrinology, Regina Margherita Children Hospital – Department of Public Health and Pediatric Sciences, University of Torino, Torino, Italy
| | - Mariangela Chiarito
- Pediatric Unit, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari “Aldo Moro”, Bari, Italy
| | - Domenico Corica
- Department of Human Pathology of Adulthood and Childhood, University of Messina, Messina, Italy
- Pediatric Unit, Gaetano Martino University Hospital of Messina, Messina, Italy
| | - Francesca Di Candia
- Department of Translational and Medical Science, Section of Pediatrics, University of Naples Federico II, Naples, Italy
| | | | - Nadia Fratangeli
- Division of Auxology, Istituto Auxologico Italiano, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Verbania, Italy
| | - Nicola Improda
- Neuro-endocrine Diseases and Obesity Unit, Department of Neurosciences, Santobono-Pausilipon Children’s Hospital, Naples, Italy
| | | | - Chiara Mozzato
- Child and Women Health Department, University of Padova, Padova, Italy
| | - Virginia Rossi
- Pediatric Department, Buzzi Children’s Hospital, Milano, Italy
| | | | - Giovanni Farello
- Department of Clinical Medicine, Public Health, Life and Environmental Sciences, University of L’Aquila, L’Aquila, Italy
| | - Lorenzo Iughetti
- Department of Medical and Surgical Sciences for Mother, Children and Adults, Pediatric Unit, University of Modena and Reggio Emilia, Modena, Italy
| | - Vincenzo Salpietro
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L’Aquila, Italy
| | | | - Mara Giordano
- Laboratory of Genetics, Struttura Complessa a Direzione Universitaria (SCDU) Biochimica Clinica, Ospedale Maggiore della Carità, Novara, Italy
- Department of Health Sciences, University of Piemonte Orientale, Novara, Italy
| | - Graziano Grugni
- Division of Auxology, Istituto Auxologico Italiano, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Verbania, Italy
| | - Maurizio Delvecchio
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L’Aquila, Italy
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Mim RA, Soorajkumar A, Kosaji N, Rahman MM, Sarker S, Karuvantevida N, Eshaque TB, Rahaman MA, Islam A, Chowdhury MSJ, Shams N, Uddin KMF, Akter H, Uddin M. Expanding deep phenotypic spectrum associated with atypical pathogenic structural variations overlapping 15q11-q13 imprinting region. Brain Behav 2024; 14:e3437. [PMID: 38616334 PMCID: PMC11016631 DOI: 10.1002/brb3.3437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 04/16/2024] Open
Abstract
BACKGROUND The 15q11-q13 region is a genetic locus with genes subject to genomic imprinting, significantly influencing neurodevelopment. Genomic imprinting is an epigenetic phenomenon that causes differential gene expression based on the parent of origin. In most diploid organisms, gene expression typically involves an equal contribution from both maternal and paternal alleles, shaping the phenotype. Nevertheless, in mammals, including humans, mice, and marsupials, the functional equivalence of parental alleles is not universally maintained. Notably, during male and female gametogenesis, parental alleles may undergo differential marking or imprinting, thereby modifying gene expression without altering the underlying DNA sequence. Neurodevelopmental disorders, such as Prader-Willi syndrome (PWS) (resulting from the absence of paternally expressed genes in this region), Angelman syndrome (AS) (associated with the absence of the maternally expressed UBE3A gene), and 15q11-q13 duplication syndrome (resulting from the two common forms of duplications-either an extra isodicentric 15 chromosome or an interstitial 15 duplication), are the outcomes of genetic variations in this imprinting region. METHODS Conducted a genomic study to identify the frequency of pathogenic variants impacting the 15q11-q13 region in an ethnically homogenous population from Bangladesh. Screened all known disorders from the DECIPHER database and identified variant enrichment within this cohort. Using the Horizon analysis platform, performed enrichment analysis, requiring at least >60% overlap between a copy number variation and a disorder breakpoint. Deep clinical phenotyping was carried out through multiple examination sessions to evaluate a range of clinical symptoms. RESULTS This study included eight individuals with clinically suspected PWS/AS, all previously confirmed through chromosomal microarray analysis, which revealed chromosomal breakpoints within the 15q11-q13 region. Among this cohort, six cases (75%) exhibited variable lengths of deletions, whereas two cases (25%) showed duplications. These included one type 2 duplication, one larger atypical duplication, one shorter type 2 deletion, one larger type 1 deletion, and four cases with atypical deletions. Furthermore, thorough clinical assessments led to the diagnosis of four PWS patients, two AS patients, and two individuals with 15q11-q13 duplication syndrome. CONCLUSION Our deep phenotypic observations identified a spectrum of clinical features that overlap and are unique to PWS, AS, and Dup15q syndromes. Our findings establish genotype-phenotype correlation for patients impacted by variable structural variations within the 15q11-q13 region.
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Affiliation(s)
- Rabeya Akter Mim
- Genetics and Genomic Medicine Centre (GGMC)NeuroGen HealthcareDhakaBangladesh
| | - Anjana Soorajkumar
- Center for Applied and Translational Genomics (CATG)Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai HealthDubaiUAE
| | - Noor Kosaji
- Center for Applied and Translational Genomics (CATG)Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai HealthDubaiUAE
| | - Muhammad Mizanur Rahman
- Department of Paediatric NeurologyBangabandhu Sheikh Mujib Medical UniversityDhakaBangladesh
| | - Shaoli Sarker
- Genetics and Genomic Medicine Centre (GGMC)NeuroGen HealthcareDhakaBangladesh
- Bangladesh Shishu Hospital and InstituteDhakaBangladesh
| | - Noushad Karuvantevida
- Center for Applied and Translational Genomics (CATG)Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai HealthDubaiUAE
| | | | - Md Atikur Rahaman
- Genetics and Genomic Medicine Centre (GGMC)NeuroGen HealthcareDhakaBangladesh
| | - Amirul Islam
- Genetics and Genomic Medicine Centre (GGMC)NeuroGen HealthcareDhakaBangladesh
- GenomeArc Inc.MississaugaOntarioCanada
| | - Mohammod Shah Jahan Chowdhury
- Genetics and Genomic Medicine Centre (GGMC)NeuroGen HealthcareDhakaBangladesh
- Ministry of Health and Family WelfareDhakaBangladesh
| | - Nusrat Shams
- Genetics and Genomic Medicine Centre (GGMC)NeuroGen HealthcareDhakaBangladesh
- National Institute of Neuroscience and HospitalDhakaBangladesh
| | - K. M. Furkan Uddin
- Genetics and Genomic Medicine Centre (GGMC)NeuroGen HealthcareDhakaBangladesh
| | - Hosneara Akter
- Genetics and Genomic Medicine Centre (GGMC)NeuroGen HealthcareDhakaBangladesh
| | - Mohammed Uddin
- Center for Applied and Translational Genomics (CATG)Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai HealthDubaiUAE
- GenomeArc Inc.MississaugaOntarioCanada
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Oto Y, Murakami N, Imatani K, Inoue T, Itabashi H, Shiraishi M, Nitta A, Matsubara K, Kobayashi S, Ihara H, Nagai T, Matsubara T. Perinatal and neonatal characteristics of Prader-Willi syndrome in Japan. Pediatr Int 2023; 65:e15540. [PMID: 36975754 DOI: 10.1111/ped.15540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 03/15/2023] [Accepted: 03/17/2023] [Indexed: 03/29/2023]
Abstract
BACKGROUND Prader-Willi syndrome (PWS) is suspected at birth if extreme hypotonia, difficulty in feeding, hypogonadism, and failure to thrive are present. Genetic diagnosis of PWS can generally be made within the first few months of life; however, a delayed diagnosis of PWS is frequently reported. Although the clinical characteristics of perinatal and neonatal patients with PWS have been reported, there are no such reports on the clinical characteristics of these patients in Japan. METHODS This retrospective, single-center study involved 177 Japanese patients with PWS and their medical data regarding the perinatal and neonatal periods were evaluated. RESULTS The median maternal age at birth was 34 years; 12.7% of the mothers had a history of assisted reproductive technology (ART). Of the mothers, 13.5% reported polyhydramnios and 4.3% had oligohydramnios. Decreased fetal movement during pregnancy was reported by 76% of the mothers. A total of 60.5% of patients were born by cesarean section. Genetic subtypes included deletions (66.1%), uniparental disomy (31.0%), imprinting defects (0.6%), and other or unknown subtypes (2.3%). The median birth length was 47.5 cm and the median birthweight was 2476 g. Of the 160 patients, 14 (8.8%) were classified as small for gestational age. Most patients had hypotonia (98.8%), and 89.3% required gavage feeding at birth. Breathing problems, congenital heart disease, and undescended testis were noted in 33.1%, 7.0%, and 93.5% of patients, respectively. CONCLUSION In our study, higher rates of ART, polyhydramnios, decreased fetal movements, cesarean section, hypotonia, feeding difficulties, and undescended testis were observed in PWS.
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Affiliation(s)
- Yuji Oto
- Department of Pediatrics, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan
| | - Nobuyuki Murakami
- Department of Pediatrics, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan
| | - Kaishi Imatani
- Department of Pediatrics, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan
| | - Takeshi Inoue
- Department of Pediatrics, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan
| | - Hisashi Itabashi
- Department of Pediatrics, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan
| | - Masahisa Shiraishi
- Department of Pediatrics, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan
| | - Akihisa Nitta
- Department of Pediatrics, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan
| | - Keiko Matsubara
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan
- Division of Collaborative Research, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Sayuki Kobayashi
- Department of Cardiology, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan
| | - Hiroshi Ihara
- Department of Psychiatry, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan
| | - Toshiro Nagai
- Nakagawanosato Ryoiku Center, kitakatsushika-gun, Saitama, Japan
| | - Tomoyo Matsubara
- Department of Pediatrics, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan
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Poitou C, Holland A, Höybye C, de Graaff LCG, Bottius S, Otterlei B, Tauber M. The transition from pediatric to adult care in individuals with Prader-Willi syndrome. Endocr Connect 2023; 12:e220373. [PMID: 36347048 PMCID: PMC9782397 DOI: 10.1530/ec-22-0373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 11/08/2022] [Indexed: 11/09/2022]
Abstract
Prader-Willi syndrome (PWS), the most common form of syndromic obesity, is a complex neurodevelopmental genetic disorder including obesity with hyperphagia, endocrine and metabolic disorders and also psychiatric disorders. The most frequent endocrine disturbances include hypogonadism and growth hormone (GH) deficiency. Hypothyroidism and central adrenal insufficiency can also be observed but are less frequent. The transition of individuals with PWS from adolescence to adult life is challenging because of multiple comorbidities and complex disabilities. Individuals and caregivers face psychological, medical and social issues. This period of profound changes is thus prone to disruptions, and the main risks being the worsening of the medical situation and loss to follow-up of the individuals. Medical care may be poorly adapted to the needs of individuals because of a lack of knowledge concerning the syndrome and also lack of the necessary specific skills. A multidisciplinary panel composed of several experts in PWS met in November 2021 during an European Reference Network on Rare Endocrine Conditions (Endo-ERN) webinar. They presented complementary aspects of PWS from the perspective of the transition including psychiatric, pediatric and adult endocrinological and parent's and patient's points of view and shed light on the best way to approach this pivotal period.
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Affiliation(s)
- Christine Poitou
- Assistance Publique-Hôpitaux de Paris, Centre de référence Maladies Rares (PRADORT, Syndrome de Prader-Willi et autres formes rares d’obésité avec troubles du comportement alimentaire), Service de Nutrition, Hôpital Pitié-Salpêtrière, Paris, France
| | | | - Charlotte Höybye
- Department of Endocrinology and Department of Molecular Medicine and Surgery, Karolinska University Hospital and Karolinska Institute, Stockholm, Sweden
| | - Laura C G de Graaff
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Sandrine Bottius
- Assistance Publique-Hôpitaux de Paris, Centre de référence Maladies Rares (PRADORT, Syndrome de Prader-Willi et autres formes rares d’obésité avec troubles du comportement alimentaire), Service de Nutrition, Hôpital Pitié-Salpêtrière, Paris, France
| | - Berit Otterlei
- Landsforeningen for Prader-Willis Syndrom Hiltonåsen, Slependen, Norway
| | - Maithé Tauber
- Centre de référence Maladies Rares (PRADORT, Syndrome de Prader-Willi et autres formes rares d’obésité avec troubles du comportement alimentaire), Service d’Endocrinologie, Obésités, Maladies Osseuses, Génétique et Gynécologie Médicale, Hôpital des Enfants, Toulouse, France
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Atypical 15q11.2-q13 Deletions and the Prader-Willi Phenotype. J Clin Med 2022; 11:jcm11154636. [PMID: 35956251 PMCID: PMC9369699 DOI: 10.3390/jcm11154636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/04/2022] [Accepted: 08/06/2022] [Indexed: 11/17/2022] Open
Abstract
Background: Prader-Willi syndrome (PWS) is a rare genetic disorder resulting from the lack of expression of the PWS region (locus q11-q13) on the paternally derived chromosome 15, as a result of a type I or II paternal deletion (50%), maternal uniparental disomy (43%), imprinting defect (4%) or translocation (<1%). In very rare cases, atypical deletions, smaller or larger than the typical deletion, are identified. These patients may have distinct phenotypical features and provide further information regarding the genotype−phenotype correlation in PWS. Methods: A prospective study in eight patients (six males and two females) with an atypical deletion in the PWS region accompanies an overview of reported cases. Results: All patients had hypotonia (100%) and many had typical PWS facial characteristics (75%), social and emotional developmental delays (75%), intellectual disabilities (50%), neonatal feeding problems and tube feeding (63%), history of obesity (50%), hyperphagia (50%) and scoliosis (50%). All males had cryptorchidism. Two patients had two separate deletions in the PWS critical region. Conclusions: Our findings provide further insight into PWS genotype−phenotype correlations; our results imply that inclusion of both SNURF-SNPRN and SNORD-116 genes in the deletion leads to a more complete PWS phenotype. A larger deletion, extending further upstream and downstream from these genes, does not cause a more severe phenotype. Conventional PWS methylation testing may miss small deletions, which can be identified using targeted next generation sequencing. PWS’s phenotypic diversity might be caused by differentially methylated regions outside the 15q11.2 locus.
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