PWS is the first clarified genetic disease affecting multisystem[4]. In most cases, this disease is sporadic and the etiology is the gene defect in the imprinted gene region of chromosome 15 (15q11-q13), which contains key genes such as SNRPN, NDN, MAGEL2, MKRN3, UBE3A, etc[7]. If the gene defect comes from the paternal strand, it will lead to PWS, and if the gene defect comes from the maternal strand, it will cause Angelman syndrome (AS; OMIM: 105830). The current clinical diagnosis mainly refers to the standards of Holm et al. in 1993[8] and the revised criteria of Cassidy et al. in 2012[6]. The major clinical manifestations of PWS during infancy include growth retardation and delayed language and motor development, short stature and cognitive deficiency in childhood, and obesity, prominent growth retardation, gonadal dysplasia, juvenile-onset diabetes mellitus, abnormal behavior and learning difficulties in adolescence. Obesity and its complications are the major causes of morbidity and mortality in PWS[9]. From the early stage, patients with PWS present severe obesity, and it often causes T2DM and the prevalence of T2DM in PWS is approximately 25% [10]. Despite the high prevalence of DM, few data were reported regarding diabetic kidney disease (DKD) in PWS[11, 12]. According to a Japanese cohort, 5.9% showed proteinuria (> 300 mg/g), and 23.5% showed microalbuminuria (30–300 mg/g) of DKD in PWS[12].This has been the only available data regarding diabetes kidney disease (DKD) in PWS. Hardly even any report of PWS combined with diabetes mellitus and massive proteinuria (proteinuria > 3.5 g/24 h).
This patient presented with cryptorchidism in infancy, obesity in childhood, prominent growth retardation, and juvenile-onset diabetes mellitus in adolescence, and he experienced the typical progression of PWS. However, the patient was not adequately recognized in infancy, childhood and adolescence, and the best time for treatment was missed because of the failure to make a definite diagnosis during his previous visits. Due to the lack of early diagnosis and treatment, the patient was admitted to our hospital on this occasion with signs of nephrotic syndrome and acute kidney injury in addition to poor glycemic control. Despite active treatment, the renal function could not be recovered, and the patient finally entered ESRD to start renal replacement therapy. During the later follow-up of the patient, he maintained dialysis at a hospital in his hometown and eventually died following a traumatic fracture and infection. In a survey conducted in the United States, the mean age of death in patients with PWS was 29.5 ± 16 years (range 2 months to 67 years) [13]. Another study also mentioned that the average age at death was 31.6 years (SD = 14.5), with the oldest individual with PWS dying at 59 years of age and the youngest dying at 1 year of age. Although not statistically significant, the diagnosis time of the deceased individuals was later than that of the living individuals (7.4 vs. 3.8 years)[14]. Therefore, early diagnosis, long-term treatment and follow-up have an important impact on improving the prognosis of PWS.
The clinical scoring system for PWS is susceptible to factors such as age, disease duration and ethnicity, leading to missed diagnosis or misdiagnosis. The risk of recurrence of PWS could results from different genetic mechanisms. Therefore, genetic diagnosis and identification of the genetic mechanism are necessary. The pathogenesis of PWS is the genetic abnormality on chromosome 15q11.2-13, which can be caused by four different types of defects: (1) deletion of the 15q11.2-13 fragment of the paternal chromosome (65%-75% in the west, 80% in China and Asia); (2) maternal uniparental disomy (mUPD)(20%-30%); (3) microdeletion and mutation in the imprinting center (1%-3%); and (4) chromosome balanced translocation (< 1%)[15, 16]. Methylation-specific polymerase chain reaction (MS-PCR) is the most widely used diagnostic technique and has the advantages of high efficiency, specificity, sensitivity, rapidity, and inexpensiveness. It has a detection rate of over 99% for PWS and can detect deletions, UPD, and imprinted center defects simultaneously, making it the preferred strategy for diagnosing PWS, but the disadvantage is that it is unable to distinguish specific genotypes[17]. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) is a standardized kit for the simultaneous detection of gene deletions, duplication mutations and methylation status at multiple chromosomal loci with the help of designed specific probes, which has high sensitivity and specificity and has gradually replaced MS-PCR for the genetic diagnosis of PWS. Chromosomal microarray analysis (CMA) can identify deletion sizes and breakpoints in deletion-type PWS and can also detect isodisomy in PWS[18]. In addition, MS-PCR can also be used for prenatal diagnosis by amniotic fluid exfoliated cells at 16–20 weeks of pregnancy[18]. In this study, the patient had a positive genetic test result, which clarified the diagnosis of PWS.
The treatment of PWS should be based on the characteristics of patients of different ages, with integrated interventions targeting endocrine metabolic disorders and psycho-behavioral problems, improving quality of life, preventing complications, and prolonging life expectancy. Behavioral treatments such as strict diet control, three-meal planning, and physical exercise are important to prevent obesity and metabolic disorders[19]. Recombinant human growth hormone therapy (rhGH) is beneficial in infants, children, and adults, and therefore, once rhGH therapy is initiated, it is recommended that treatment be continued and long-term if the actual benefits outweigh the risks[19]. Unfortunately, due to severe obesity and uncontrolled diabetes, rhGH is contraindicated in this case and cannot be used. Mille et al[20]. found that metformin was effective in improving the sense of satiety and decreasing food-related distress and anxiety in patients with PWS as well as morbid obesity. Glucagon-like peptide-1 (GLP-1) receptor agonists can suppress appetite, promote insulin secretion, and have both weight loss and hypoglycemic effects. GLP-1 receptor agonists have been used with good efficacy in the treatment of PWS[21]. In addition, with the widespread use of sodium-dependent glucose transporter 2 (SGLT-2) inhibitors, SGLT-2 inhibitor as an add-on drug to GLP-1 receptor agonists for glycemic and body weight control of patients with PWS is also effective[22]. However, in this patient, early inadequate cognition of the disease, unclear diagnosis and reduced renal function which led to a missed opportunity for treatment. In recent years, research on laparoscopic bariatric surgery in PWS patients with severe obesity has gradually increased, but different research results vary. The weight loss after bariatric surgery is more pronounced in the first 1–2 years after surgery, making it difficult to achieve sustained long-term weight loss[23, 24]. Finally, the prevention of osteoporosis and fractures is also particularly important for PWS patients. Therefore, the treatment of PWS should be individualized, early treatment after clear diagnosis, with long-term follow-up and observation.
In conclusion, PWS has a diverse clinical presentation that varies with age and has a poor prognosis. With the continuous development of medicine, clinicians should also focus on early genetic diagnosis, long-term follow-up, and in-time treatment to improve the quality of life and prognosis of patients.