The Utilization of MS-MLPA as the First-Line Test for the Diagnosis of Prader–Willi Syndrome in Thai Patients

Prader–Willi syndrome (PWS) is a genetic disorder caused by the expression disruption of genes on the paternally inherited allele of chromosome 15q11.2-q13. Apart from clinical diagnostic criteria, PWS is confirmed by genetic testing. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) is one of the molecular techniques used to analyze this syndrome. This study aimed to evaluate the concordance of the test results of MS-MLPA with conventional techniques in the diagnosis of PWS in Thai patients. Forty leftover specimens from routine genetic testing (MS-PCR and FISH) were tested to obtain MS-MLPA results. By comparison, perfect concordance was shown between the result of MS-MLPA and those of conventional techniques. In conclusion, MS-MLPA is an accurate and cost-effective assay that can be used to confirm PWS diagnosis with explicit deletion of affected genes.

Prader-Willi syndrome: an update on obesity and endocrine problems

Prader-Willi syndrome (PWS) is a rare complex genetic disorder that results from a lack of expression of the paternally inherited chromosome 15q11-q13. PWS is characterized by hypotonia and feeding difficulty in early infancy and development of morbid obesity aggravated by uncontrolled hyperphagia after childhood and adolescent. Dysmorphic facial features, delayed motor and language development, various degrees of cognitive impairment, and behavioral problems are common in PWS. Without early, intensive nutritional therapy along with behavioral modification, PWS patients develop severe obesity associated with type 2 diabetes, obstructive sleep apnea, right-side heart failure, and other obesity-related metabolic complications. Hypothalamic dysfunction in PWS can lead to several endocrine disorders, including short stature with growth hormone deficiency, hypothyroidism, central adrenal insufficiency, and hypogonadism. In this review, we discuss the natural history of PWS and the mechanisms of hyperphagia and obesity. We also provide an update on obesity treatments and recommendations for screening and monitoring of various endocrine problems that can occur in PWS.

A genome-edited β-cell model of Prader-Willi syndrome reveals chronic deficits in endoplasmic reticulum chaperones and insulin secretion

Prader-Willi syndrome (PWS) is a multisystem disorder caused by loss of expression of a cluster of paternally-expressed, imprinted genes. Neonatal failure to thrive is followed by childhood-onset hyperphagia, obesity, neurobehavioral abnormalities, and hormonal deficits. Prior evidence from a mouse model with a deletion of the orthologous PWS-gene domain identified abnormal pancreatic islet development with deficient insulin secretion, hypoglucagonemia, and postnatal onset of progressive, lethal hypoglycemia. To investigate the role of PWS-genes in β-cell secretory function, we used CRISPR/Cas9 genome-editing to generate isogenic, clonal INS-1 insulinoma lines with 3.16 Mb deletions of the silent, maternal (control) or active, paternal (PWS) alleles. PWS β-cells showed a significant reduction in basal and glucose-stimulated insulin secretion, signifying a deficiency in cell-autonomous insulin secretion. Parallel proteome and transcriptome studies revealed reduced levels of secreted peptides and twelve endoplasmic reticulum (ER) chaperones, including HSPA5 and HSP90B1. In contrast to the dosage compensation previously seen for ER chaperones in Hspa5 or Hsp90b1 gene knockouts, compensation is precluded by the widespread deficiency of ER chaperones in PWS β-cells. Consistent with the reduced ER chaperone levels, PWS INS-1 β-cells are more sensitive to ER stress, leading to earlier activation of all three arms of the unfolded protein response. These results suggest that a chronic deficit of ER chaperones in PWS β-cells leads to a delay in ER transit and/or folding of insulin and other cargo along the secretory pathway. The findings illuminate the pathophysiological basis of hormone deficits in PWS and implicate PWS-imprinted genes in β-cell secretory pathway function.

Alteration of serum leptin and LEP/LEPR promoter methylation in Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a rare neurodevelopmental disorder based on a loss of paternally expressed but maternally imprinted genes in chromosome region 15q11-13. During child development, PWS usually results in insatiable appetite with subsequent obesity representing the major mortality factor. The neurobiological basis of PWS-typical hyperphagia has remained poorly understood. Many PWS-typical abnormalities are based on hypothalamic dysregulation, the region in which hunger and satiety are hormonally regulated, with the hormone leptin being a main long-term regulator of satiety. Previous studies in PWS have inconsistently shown leptin alterations solely in early childhood, without investigating the leptin system on an epigenetic level. The present study investigates serum leptin levels (S-leptin) and methylation of the leptin (LEP) and leptin receptor gene (LEPR) promoter in 24 individuals with PWS compared to 13 healthy controls matched for sex, age, and body mass index (BMI) and relates the results to the extent of hyperphagia in PWS. S-Leptin levels were obtained by Enzyme-linked Immunosorbent Assay. LEP/LEPR-promoter methylation was assessed by DNA-bisulfite-sequencing, hyperphagia by Hyperphagia Questionnaire for Clinical Trials (HQ-CT). PWS and control groups differed significantly in S-leptin levels with higher S-leptin in PWS. Methylation analysis showed significant differences in mean promoter methylation rate both for LEP and LEPR with a lower methylation rate in PWS. LEPR, but not LEP methylation correlated with S-leptin levels. S-leptin and both LEP and LEPR methylation did not correlate with HQ-CT scores in PWS. The present study is the first to show significantly elevated S-leptin levels in an adult PWS cohort combined with an altered, downregulated LEP and LEPR promoter methylation status compared to BMI-matched controls. Analogous to previous studies, no link to the behavioral dimension could be drawn. Overall, the results suggest an increased leptin dysregulation in PWS, whereby the findings partly mirror leptin resistance seen in non-syndromic obesity.

PRADER-WILLI SYNDROME: A CLINICAL CASE

Синдром Прадера-Вилли - редкое наследственное заболевание, причиной которого является отсутствие отцовской копии участка хромосомы 15q11-13. Одним из проявлений данного генетического синдрома может быть соматотропная недостаточность. Именно низкорослость часто является поводом для обращения родителей пациента к врачу-эндокринологу. Для своевременной диагностики заболевания очень важен командный подход специалистов с участием генетика, эндокринолога, невропатолога с обязательным проведением генетического анализа. Обнаружение дефицита гормона роста и назначение соответствующей заместительной терапии повышает уровень медицинской и социальной адаптации ребенка. В данной статье описан случай синдрома Прадера-Вилли с соматотропной недостаточностью у 4-летней девочки, представлены преимущества и риски применения гормона роста. Prader-Willi syndrome is a rare hereditary disorder caused by the absence of a paternal copy of the 15q11-13 chromosome region. One of the manifestations of this genetic syndrome may be somatotropic insufficiency. It is the short stature that is often the reason for the patient's parents to contact an endocrinologist. For the timely diagnosis of the disease, a team approach of specialists with the participation of a geneticist, endocrinologist, neuropathologist with the obligatory genetic analysis is very important. Detection of growth hormone deficiency and the appointment of appropriate substitution therapy increases the level of medical and social adaptation of the child. This article describes a case of Prader-Willi syndrome with growth hormone deficiency in a 4-year-old girl, presents the benefits and risks of using growth hormone.