scholarly journals Prader-Willi syndrome: reflections on seminal studies and future therapies

Open Biology ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 200195
Author(s):  
Michael S. Chung ◽  
Maéva Langouët ◽  
Stormy J. Chamberlain ◽  
Gordon G. Carmichael
Keyword(s):  
Genomic Imprinting ◽  
Angelman Syndrome ◽  
Cpg Island ◽  
Uniparental Disomy ◽  
Large Deletion ◽  
Paternal Allele ◽  
Prader Willi Syndrome ◽  
Loss Of Function ◽  
Maternal Uniparental Disomy ◽  
Parental Allele

Prader-Willi syndrome (PWS) is caused by the loss of function of the paternally inherited 15q11-q13 locus. This region is governed by genomic imprinting, a phenomenon in which genes are expressed exclusively from one parental allele. The genomic imprinting of the 15q11-q13 locus is established in the germline and is largely controlled by a bipartite imprinting centre. One part, termed the Prader-Willi syndrome imprinting center (PWS-IC), comprises a CpG island that is unmethylated on the paternal allele and methylated on the maternal allele. The second part, termed the Angelman syndrome imprinting centre, is required to silence the PWS_IC in the maternal germline. The loss of the paternal contribution of the imprinted 15q11-q13 locus most frequently occurs owing to a large deletion of the entire imprinted region but can also occur through maternal uniparental disomy or an imprinting defect. While PWS is considered a contiguous gene syndrome based on large-deletion and uniparental disomy patients, the lack of expression of only non-coding RNA transcripts from the SNURF-SNRPN/SNHG14 may be the primary cause of PWS. Patients with small atypical deletions of the paternal SNORD116 cluster alone appear to have most of the PWS related clinical phenotypes. The loss of the maternal contribution of the 15q11-q13 locus causes a separate and distinct condition called Angelman syndrome. Importantly, while much has been learned about the regulation and expression of genes and transcripts deriving from the 15q11-q13 locus, there remains much to be learned about how these genes and transcripts contribute at the molecular level to the clinical traits and developmental aspects of PWS that have been observed.

scholarly journals Quantitative Analysis of SRNPN Gene Methylation by Pyrosequencing as a Diagnostic Test for Prader–Willi Syndrome and Angelman Syndrome

2006 ◽  
Vol 52 (6) ◽  
pp. 1005-1013 ◽  
Author(s):  
Helen E White ◽  
Victoria J Durston ◽  
John F Harvey ◽  
Nicholas CP Cross
Keyword(s):  
Diagnostic Test ◽  
Angelman Syndrome ◽  
Uniparental Disomy ◽  
Chromosome 15 ◽  
Prader Willi Syndrome ◽  
Maternal Uniparental Disomy ◽  
Cpg Sites ◽  
Specific Pcr ◽  
Small Nuclear Ribonucleoprotein ◽  
Maternal Contribution

Abstract Background: Angelman syndrome (AS) and Prader–Willi syndrome (PWS) are 2 distinct neurodevelopmental disorders caused primarily by deficiency of specific parental contributions at an imprinted domain within the chromosomal region 15q11.2-13. In most cases, lack of paternal contribution leads to PWS either by paternal deletion (∼70%) or maternal uniparental disomy (UPD; ∼30%). Most cases of AS result from the lack of a maternal contribution from this same region by maternal deletion (∼70%) or by paternal UPD (∼5%). Analysis of allelic methylation differences at the small nuclear ribonucleoprotein polypeptide N (SNRPN) locus can differentiate the maternally and paternally inherited chromosome 15 and can be used as a diagnostic test for AS and PWS. Methods: Sodium bisulfite–treated genomic DNA was PCR-amplified for the SNRPN gene. We used pyrosequencing to individually quantify the resulting artificial C/T sequence variation at CpG sites. Anonymized DNA samples from PWS patients (n = 40), AS patients (n = 31), and controls (n = 81) were analyzed in a blinded fashion with 2 PCR and 3 pyrosequencing reactions. We compared results from the pyrosequencing assays with those obtained with a commonly used methylation-specific PCR (MS-PCR) diagnostic protocol. Results: The pyrosequencing assays had a sensitivity and specificity of 100% and provided quantification of methylation at 12 CpG sites within the SNRPN locus. The resulting diagnoses were 100% concordant with those obtained from the MS-PCR protocol. Conclusions: Pyrosequencing is a rapid and robust method for quantitative methylation analysis of the SNRPN locus and can be used as a diagnostic test for PWS and AS.

Molecular Analysis of an Extra inv dup(15)(q13) Chromosome in Two Patients with Angelman Syndrome

1996 ◽  
Vol 45 (1-2) ◽  
pp. 217-220 ◽  
Author(s):  
T. Buchholz ◽  
S. Schuffenhauer ◽  
K. Evans ◽  
L. Robson ◽  
B. Appleton ◽  
...  
Keyword(s):  
Molecular Analysis ◽  
Angelman Syndrome ◽  
Uniparental Disomy ◽  
Molecular Data ◽  
Monoallelic Expression ◽  
Chromosome 15 ◽  
Prader Willi Syndrome ◽  
Loss Of Function ◽  
Maternal Allele ◽  
Molecular Defects

Angelman syndrome (AS) is caused by the loss of function of yet unidentified gene(s) which map within 15q 11-13 and show monoallelic expression from the maternal allele. Lack of the maternal allele(s), due to either a deletion on the maternal chromosome 15 (about 70% of AS patients) or a paternal uniparental disomy (UPD)15 (<5%), are the most common molecular defects in AS. Prader-Willi syndrome (PWS) also maps to proximal 15q, but is caused by the loss of function of paternally expressed gen(s) [1]. Here we describe clinical, cytogenetic and molecular data for two non-related patients with AS who carry a nonmosaic extra cromosome inv dup(15).

scholarly journals Uniparental Disomy and Genomic Imprinting in Humans

1996 ◽  
Vol 45 (1-2) ◽  
pp. 145-152
Author(s):  
A. Schinzel
Keyword(s):  
Genomic Imprinting ◽  
Uniparental Disomy ◽  
Paternal Allele ◽  
Chromosome 22 ◽  
Loss Of Function ◽  
Developmental Defects ◽  
Robertsonian Translocations ◽  
Healthy Mother ◽  
Active Allele ◽  
Or Genes

Uniparental disomy (UPD), the inheritance of both homologues from one chromosome from the same parent, was first proposed in 1980 by Erik Engel [1] to be a potential cause of congenital developmental defects in hymans. First hints from the premolecular era towards its existence came from instances where a pericentric inversion was present on one homologue in a parent and on both in one offspring [2] and where there was transmission of an interhomologous Robertsonian translocation (of chromosome 22) from a healthy mother to healthy offspring [3-4]. In mice, UPD was experimentally produced by crossing two mice lines with different Robertsonian translocations both involving the same chromosome [for 2 review see ref. 5].Through this approach, it was possible to define imprinted regions, chromosomes and chromosomal segments for which either maternal or paternal or both types of uniparental disomy led to phenotypic abnormalities. The latter are explained by genomic imprinting, the differential silencing of a gene or genes from one of the parents (the mother or the father) during any stage of embryogenesis or later in life. If, for example, the maternal homologue of a given gene is imprinted (and hence only the paternal allele is active), maternal UPD would lead to loss of the active allele and thus might cause consequences due to loss of function.

Safety and effectiveness of growth hormone therapy in infants with Prader-Willi syndrome younger than 2 years: a prospective study

2019 ◽  
Vol 32 (8) ◽  
pp. 879-884 ◽  
Author(s):  
Raquel Corripio ◽  
Carla Tubau ◽  
Laura Calvo ◽  
Carme Brun ◽  
Núria Capdevila ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Prospective Study ◽  
Mixed Model ◽  
Standard Deviation Score ◽  
Uniparental Disomy ◽  
Chromosome 15 ◽  
Prader Willi Syndrome ◽  
Gh Treatment ◽  
Maternal Uniparental Disomy ◽  
A Prospective Study

Abstract Background There is little evidence of the effects of early treatment with growth hormone (GH) in infants with Prader-Willi syndrome (PWS). A prospective study was conducted to assess the safety of GH therapy in infants younger than 2 years of age with PWS. Methods A total of 14 patients with PWS started treatment with GH under the age of 2 years and were followed over a 2-year period. A deletion of chromosome 15 was present in nine infants (64.3%) and maternal uniparental disomy 15 in five infants (35.7%). The median age at start of GH treatment was 9.6 months (interquartile range [IQR] 9.0–18.3 months). Changes in height standard deviation score (SDS), body mass index (BMI) SDS and subcapsular and tricipital skinfolds in the follow-up period were evaluated with a mixed-model regression analysis using the Package R. Results There were no fatal adverse events. A significant decrease (p < 0.001) in tricipital and subcapsular skinfold thickness, with an upward trend of height SDS and a downward trend of BMI SDS, was observed. Infants who started GH before 15 months of age started walking at a median of 18.0 [17.0–19.5] months vs. 36.6 [36.3–37.8] months for those who began treatment with GH after 15 months of age (p = 0.024). Conclusions GH treatment in infants with PWS less than 2 years of age is safe and improved body composition. Infants who received GH before the age of 15 months started to walk earlier.

scholarly journals Sleep-Related Breathing Disorders in Young Adults With Prader-Willi Syndrome: A Placebo-Controlled, Crossover GH Trial

2019 ◽  
Vol 104 (9) ◽  
pp. 3931-3938
Author(s):  
Stephany H Donze ◽  
Al W de Weerd ◽  
Renilde A S van den Bossche ◽  
Koen F M Joosten ◽  
Anita C S Hokken-Koelega
Keyword(s):  
Young Adults ◽  
Adult Height ◽  
Uniparental Disomy ◽  
Apnea Hypopnea Index ◽  
Prader Willi Syndrome ◽  
Double Blind ◽  
Sleep Related Breathing Disorders ◽  
Maternal Uniparental Disomy ◽  
Breathing Disorders ◽  
Obstructive Sleep

Abstract Context Sleep-related breathing disorders (SRBD) are common in people with Prader-Willi syndrome (PWS). Young adults with PWS benefit from GH continuation after attaining adult height by maintaining the improved body composition obtained during childhood. There are, no studies about the effects of GH on SRBD in young adults with PWS who were treated with GH during childhood. Objective Investigate the effects of GH vs placebo on SRBD in young adults with PWS who were treated with GH during childhood and had attained adult height. Design Two-year, randomized, double-blind, placebo-controlled, crossover study in 27 young adults with PWS, stratified for sex and body mass index. Setting Dutch PWS Reference Center. Intervention Crossover intervention with GH (0.67 mg/m2/d) and placebo, both over one year. Main Outcome Measures Apnea hypopnea index (AHI), obstructive apnea index (OAI), central apnea index (CAI), measured by polysomnography. Results Compared with placebo, GH did not increase AHI, CAI, or OAI (P &gt; 0.35). The effect of GH vs placebo was neither different between men and women, nor between patients with a deletion or maternal uniparental disomy/imprinting center defect. After two years, there was no difference in AHI, CAI, or OAI compared with baseline (P &gt; 0.18). Two patients (7%) fulfilled the criteria of obstructive sleep apnea regardless of GH or placebo. Conclusions GH compared with placebo does not cause a substantial increase in AHI, CAI, or OAI in adults with PWS who were treated with GH during childhood and have attained adult height. Our findings are reassuring and prove that GH can be administered safely.

Prader-Willi and Angelman Syndromes and the Implications of Genomic Imprinting in Their Etiology

1996 ◽  
Vol 45 (1-2) ◽  
pp. 15-16
Author(s):  
S.B. Cassidy
Keyword(s):  
Genomic Imprinting ◽  
Hypogonadotropic Hypogonadism ◽  
Uniparental Disomy ◽  
Failure To Thrive ◽  
Chromosome 15 ◽  
Sleep Regulation ◽  
Obsessive Compulsive ◽  
Maternal Uniparental Disomy ◽  
Normal Human ◽  
Human Disorder

The unfolding of the genetic story of Prader-Willi and Angelman syndromes provided the first recognition of human genomic imprinting. These disorders, which are clinically very distinct, are related through their genomic proximity and the inverse direction of the imprinting which affects them. Both are interesting disorders in themselves, especially in that both have distinctive behavioral patterns among their clinical features that may teach us much about normal human behavior.Prader-Willi syndrome (PWS) is a complex multi-system condition whose major features include infantile hypotonia with decreased arousal, poor suck and failure-to-thrive; characteristic dysmorphic facial features; hypopigmentation; childhood onset of obesity due to lack of satiety; hypogonadotropic hypogonadism with genital hypoplasia and delayed and incomplete puberty; short stature for genetic background; developmental delay and usually mild mental retardation; and a characteristic behavioral disturbance with temper tantrums and obsessive-compulsive behavior. PWS occurs in about 1/15,000 people. Since its first description in 1956, it has been apparent that many of these features arise from insufficient function of the hypothalamus, and recent identification of neurosecretory growth hormone insufficiency and temperature and sleep regulation abnormalities support this. However, no visible gross or microscopic abnormalities of the hypothalamus are seen on neuropathology. The finding of a chromosome 15q 11-13 deletion in a proportion of patients with PWS by Ledbetter and colleagues in 1981 was the first window to the exciting genetic discoveries of the past decade, including recognition (initially by Butler and Palmer) that the deletion is always on the paternally-derived chromosome 15 in PWS, and the finding by Nicholls and coworkers that the vast majority of the remainder of patients had normal chromosomes but had maternal uniparental disomy (UPD). Nearly all patients with clinically typical PWS have either 15q deletion (about 75%) or maternal UPD (about 25%). This is the first human disorder that was recognized to result from uniparental disomy, and lead to many insights into imprinting.

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