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Prevalence of pathogenetic MC4R mutations in Italian children with early onset obesity, tall stature and familial history of obesity.

Santoro N, Cirillo G, Xiang Z, Tanas R, Greggio N, Morino G, Iughetti L, Vottero A, Salvatoni A, Di Pietro M, Balsamo A, Crinò A, Grandone A, Haskell-Luevano C, Perrone L, del Giudice EM - BMC Med. Genet. (2009)

Bottom Line: The S127L (C380T), found in three unrelated children, had been described and functionally characterized previously.The Q307X (C919T) and the Y332H (T994C) mutations were found in two patients.Functional studies showed that only Q307X impaired protein function.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Pediatria F, Fede, Seconda Università degli Studi di Napoli, Napoli, Italy. nicolasantoro@hotmail.com

ABSTRACT

Background: Melanocortin-4-receptor (MC4R) mutations represent the most frequent genetic cause of non-syndromic early onset obesity. Children carrying MC4R mutations seem to show a particular phenotype characterized by early onset, severe obesity and high stature. To verify whether MC4R mutations are associated with this particular phenotype in the Italian pediatric population, we decided to screen the MC4R gene in a group of obese children selected on the basis of their phenotype.

Methods: To perform this study, a multicentric approach was designed. Particularly, to be enrolled in the study subjects needed to meet the following criteria: Body mass index > or = 3 deviation scores according to age and sex, familiar history of obesity (at least one parent obese), obesity onset before the 10 years old, height > or = 2 deviation scores. The coding region of MC4R gene was screened in 240 obese children (mean age 8.3 +/- 3.1, mean BMI 30.8 +/- 5.4) and in 200 controls (mean age 8.1 +/- 2.8; mean BMI 14.2 +/- 2.5).

Results: Three mutations have been found in five obese children. The S127L (C380T), found in three unrelated children, had been described and functionally characterized previously. The Q307X (C919T) and the Y332H (T994C) mutations were found in two patients. Functional studies showed that only Q307X impaired protein function.

Conclusion: The low prevalence of MC4R mutations (1.6%) in this group of obese children selected according to the obesity degree, the tall stature and the family history of obesity was similar to the prevalence observed in previous screenings performed in obese adults and in not phenotypically selected obese children.

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FACS Data. Fluorescence activated cell sorting analysis (FACS) of the MC4R Q307X mutation expressed in HEK-293. The total cell receptor expression levels were determined using permeabilized cells measuring both cell surface and intracellular protein expression. The cell surface expression levels were determined using non-permeabilized cells. Cell expression levels are presented relative to the wild type human-MC4R control. Total Q307X expression was 88%, surface expression was 31% and intracellular retention was about 57%.
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Figure 5: FACS Data. Fluorescence activated cell sorting analysis (FACS) of the MC4R Q307X mutation expressed in HEK-293. The total cell receptor expression levels were determined using permeabilized cells measuring both cell surface and intracellular protein expression. The cell surface expression levels were determined using non-permeabilized cells. Cell expression levels are presented relative to the wild type human-MC4R control. Total Q307X expression was 88%, surface expression was 31% and intracellular retention was about 57%.

Mentions: As intracellular retention of mutated MC4Rs is a common obesity-causing defect, to allow for the rapid evaluation of cell surface expression of Q307X relative to total expression of the receptor in individual transiently transfected cells, a method based on immunostaining and fluorescence detection by flow cytometry has been used. As compared to the wild type expression, total Q307X expression was 88%, surface expression was 31% and, therefore, intracellular retention was about 57% (figure 5).


Prevalence of pathogenetic MC4R mutations in Italian children with early onset obesity, tall stature and familial history of obesity.

Santoro N, Cirillo G, Xiang Z, Tanas R, Greggio N, Morino G, Iughetti L, Vottero A, Salvatoni A, Di Pietro M, Balsamo A, Crinò A, Grandone A, Haskell-Luevano C, Perrone L, del Giudice EM - BMC Med. Genet. (2009)

FACS Data. Fluorescence activated cell sorting analysis (FACS) of the MC4R Q307X mutation expressed in HEK-293. The total cell receptor expression levels were determined using permeabilized cells measuring both cell surface and intracellular protein expression. The cell surface expression levels were determined using non-permeabilized cells. Cell expression levels are presented relative to the wild type human-MC4R control. Total Q307X expression was 88%, surface expression was 31% and intracellular retention was about 57%.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2664798&req=5

Figure 5: FACS Data. Fluorescence activated cell sorting analysis (FACS) of the MC4R Q307X mutation expressed in HEK-293. The total cell receptor expression levels were determined using permeabilized cells measuring both cell surface and intracellular protein expression. The cell surface expression levels were determined using non-permeabilized cells. Cell expression levels are presented relative to the wild type human-MC4R control. Total Q307X expression was 88%, surface expression was 31% and intracellular retention was about 57%.
Mentions: As intracellular retention of mutated MC4Rs is a common obesity-causing defect, to allow for the rapid evaluation of cell surface expression of Q307X relative to total expression of the receptor in individual transiently transfected cells, a method based on immunostaining and fluorescence detection by flow cytometry has been used. As compared to the wild type expression, total Q307X expression was 88%, surface expression was 31% and, therefore, intracellular retention was about 57% (figure 5).

Bottom Line: The S127L (C380T), found in three unrelated children, had been described and functionally characterized previously.The Q307X (C919T) and the Y332H (T994C) mutations were found in two patients.Functional studies showed that only Q307X impaired protein function.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Pediatria F, Fede, Seconda Università degli Studi di Napoli, Napoli, Italy. nicolasantoro@hotmail.com

ABSTRACT

Background: Melanocortin-4-receptor (MC4R) mutations represent the most frequent genetic cause of non-syndromic early onset obesity. Children carrying MC4R mutations seem to show a particular phenotype characterized by early onset, severe obesity and high stature. To verify whether MC4R mutations are associated with this particular phenotype in the Italian pediatric population, we decided to screen the MC4R gene in a group of obese children selected on the basis of their phenotype.

Methods: To perform this study, a multicentric approach was designed. Particularly, to be enrolled in the study subjects needed to meet the following criteria: Body mass index > or = 3 deviation scores according to age and sex, familiar history of obesity (at least one parent obese), obesity onset before the 10 years old, height > or = 2 deviation scores. The coding region of MC4R gene was screened in 240 obese children (mean age 8.3 +/- 3.1, mean BMI 30.8 +/- 5.4) and in 200 controls (mean age 8.1 +/- 2.8; mean BMI 14.2 +/- 2.5).

Results: Three mutations have been found in five obese children. The S127L (C380T), found in three unrelated children, had been described and functionally characterized previously. The Q307X (C919T) and the Y332H (T994C) mutations were found in two patients. Functional studies showed that only Q307X impaired protein function.

Conclusion: The low prevalence of MC4R mutations (1.6%) in this group of obese children selected according to the obesity degree, the tall stature and the family history of obesity was similar to the prevalence observed in previous screenings performed in obese adults and in not phenotypically selected obese children.

Show MeSH
Related in: MedlinePlus