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Salivary abnormalities in Prader-Willi syndrome
1Department of Pediatrics/Section on Medical Genetics, Bowman Gray School of Medicine, Winston-Salem, North Carolina 27157, USA. pshart@bgsm.edu
Insights
Prader-Willi syndrome (PWS) patients exhibit significantly reduced salivary flow and altered saliva composition. These salivary changes, including concentrated ions and proteins, occur in both deletion and maternal uniparental disomy cases, indicating imprinting
Area of Science:
- Genetics
- Endocrinology
- Developmental Biology
Background:
- Prader-Willi syndrome (PWS) is a complex genetic disorder.
- PWS is characterized by growth retardation, hypotonia, and hyperphagia leading to obesity.
- Genetic causes include paternal 15q11q13 deletion or maternal uniparental disomy (UPD).
Purpose of the Study:
- To investigate salivary flow rate and composition in individuals with Prader-Willi syndrome.
- To determine if salivary abnormalities are consistent across different genetic causes of PWS.
Main Methods:
- Quantitative analysis of salivary gland function.
- Biochemical analysis of salivary components (ions, proteins).
- Comparison of PWS patients (deletion and UPD) with healthy controls.
Main Results:
- Patients with PWS showed approximately 20% of normal salivary flow rates.
- Saliva from PWS patients had increased concentrations of ions and proteins.
- These salivary findings were observed in both deletion and maternal UPD subgroups.
Conclusions:
- Reduced salivary flow and altered composition are characteristic of Prader-Willi syndrome.
- The consistent findings suggest the involvement of imprinted genes in salivary gland regulation.
- Further research into the specific imprinted genes is warranted.
Abstract:
Prader-Willi syndrome (PWS) is characterized by psychomotor and growth retardation, infantile hypotonia, characteristic facies, small hands and feet, dental abnormalities, and early onset of childhood hyperphagia with consequent obesity. PWS is associated with abnormalities of chromosome 15. Approximately 75% of patients have a deletion of 15q11q13 on the paternal homologue, whereas 20-25% have inherited both chromosome 15s from the mother and none from the father, a condition known as maternal uniparental disomy (UPD). Thus, it is a lack of paternal alleles in the 15q11q13 region that results in PWS. Thick, sticky saliva is a consistent finding in patients with PWS. We have characterized salivary flow and composition in individuals with PWS. Salivary flow in patients with PWS is approximately 20% of that in controls. In addition, the salivary ions and proteins are present in increased amounts, possibly reflecting a concentration effect relative to decreased water in the saliva. Both deletion and uniparental disomy patients exhibit these findings, suggesting that the gene(s) involved are subject to imprinting.