Severe symptoms of Prader-Willi syndrome are associated with a specific genetic deletion

Overview of patients with atypical deletions Prader-Willi syndrome (PWS) suggests file deletions SNURF-SNPRN And the SNORD-116 A new study suggests that genes are necessary for the development of the main symptoms of Prader-Willi syndrome.

the study “Atypical 15q11.2-q13 deletions and Prader-Willi phenotypeAnd thePosted in Journal of Clinical Medicine.

The syndrome is caused by a loss or defect in genes in a specific region of chromosome 15, the locus of the syndrome. In most cases, the paternal chromosome 15 genes are deleted or lost. These genes are associated with appetite, metabolism, growth, intellectual function, and social behavior.

Genetic deletions are usually the result of random errors and may affect different numbers of genes in the PWS region (type I large or type II short). In rare cases, atypical deletions, shorter or larger than usual, are identified.

Researchers in the Netherlands described eight Prader-Willi syndrome patients (six males and two women) with atypical deletions in relation to genetic causes and their relationship with Symptoms of the syndrome.

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Genetic characterization was performed by a methylation assay, which detects the state of DNA methylation. When genes are methylated, that is, when methyl groups are added to a DNA molecule, they are silenced (without activity).

All eight patients had hypotonia, meaning low muscle tone, and all males had cryptorchidism—the absence of at least one testicle. Several presented the typical facial characteristics of Prader-Willi syndrome (75%), social and emotional delays (75%), problems with newborn and tube feeding (63%), intellectual disabilities (50%), a history of obesity (50%), and excessive eat the food. (50%) and lateral curvature of the spine (50%).

Previous studies identified the core PWS area – which includes SNURF And the SNPRN Genes – sufficient to cause typical symptoms of Prader-Willi syndrome. In this study, seven of the eight had a deletion SNURF-SNPRN genes.

The risk is related to a specific deletion

The patient who did not include it deleted SNURF-SNPRN Gene was a 4-year-old boy with hypotonia, developmental delay and short stature, although within normal height. It lacked some distinct PWS features and had an average IQ. He was not obese and had no increased appetite (hypereating) at the last reported assessment at age 4, the age at which weight gain associated with Prader-Willi syndrome occurs.

Another patient, an 11-year-old girl, had a deletion of a very small portion of her SNURF-SNPRN region. She was of medium height and lacked many of the characteristics of Prader-Willi syndrome, such as severe hypotonia and facial features. However, she was obese, overeating, and had a lower than average IQ. She was registered in Special Education.

According to the research team, this case, along with other cases reported in other studies, suggest that intellectual disability in the syndrome may be related to a deletion of SNURF-SNPRN region. Those with larger deletions in the PWS region can show average IQ.

Intellectual disability in the syndrome may be related to impairment SNURF-SNPRN gene,” the researchers wrote.

The SNURF-SNPRN However, it may not be a cause of low stature.

“None of the patients with a small deletion or point mutation in SNURF-SNPRN He was short in stature, which may mean that this feature of PWS may not be caused by inactivation or deletion of the SNURF-SNPRN gene,” the researchers wrote.

Furthermore, in six of eight patients, deletions were reported in snord 116 A gene known to be associated with the syndrome.

A 12-year-old girl had deletions involving both SNURF-SNPRN And the We will supply 116. She had severe intellectual and behavioral disability and scoliosis. A 4-year-old had a relatively small deletion that also included SNURF-SNPRN And the snord 116 Genes, presented below average IQ, decreased performance, and overeating.

Patients with relatively large deletions do not appear to have more severe disease, compared to patients with smaller deletions, including SNURF-SNPRN And the snord 116.

In fact, the main symptoms of Prader-Willi syndrome are found in patients with deletions SNURF-SNPRN And the snord 116 genes. Patients with deletions in any of these genes lost some specific disease symptoms, such as short stature or intellectual disability. If both genes were deleted, the phenotype was severe, compared to patients with larger Prader-Willi syndrome deletions.

Our results suggest that both are included SNURF-SNPRN And the SNORD-116 Genes in deletions lead to the more complete phenotype of Prader-Willi syndrome [disease]. The larger deletions, which extend further upstream and downstream of these genes, do not cause a more severe phenotype, the researchers wrote.

The data” indicates that both SNURF-SNRPN And the snord 116 They contribute to the Prader-Willi syndrome phenotype, but these downstream and upstream genes may be less important,” they conclude.

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