Periodontitis and Inflammation in Children With Down Syndrome/Trisomy 21: Study on Biological Samples

Since 2018, the Chicago Classification of Periodontal Diseases and Conditions, has listed Down syndrome (DS)/trisomy 21 (T21) as a systemic disease with periodontal implications. Numerous studies report an increased prevalence and severity of periodontitis in DS/T21 individuals under the age of 35. Approximately 35% of adolescents with DS show early signs of alveolar bone loss. However, very few studies have examined the role of immune deficiency in DS/T21 patients in the pathogenesis of periodontitis. Indeed, periodontitis induced by bacterial plaque is virtually non-existent in the paediatric population, leaving the field to systemically-induced periodontitis.

The investigators hypothesize that specific neutrophil phenotypes in DS/T21 patients are key to explaining the rapid progression to periodontitis.

Investigator's primary objective is to characterize the different oral and blood neutrophil subtypes in DS/T21 children with gingival inflammation.

Investigator's secondary objective is to assess the involvement of different neutrophil subtypes in early periodontitis in children with DS/T21.

It's a cross-sectional, monocenter, prospective, open-label, non-randomized case control study to collect saliva and serum samples as part of the patient's routine care in oral medicine department to form a biological collection.

Patients will be recruited in the oral medicine department of AP-HP Charles Foix hospital (Ivry/Seine) by periodontists in 2 groups (CASES: Group 1 for children with DS/T21 divided into 2 subgroups according the periodontal health, and CONTROLS: Group 2 divided into 4 subgroups according to the systemic and periodontal health) Inclusion period is 12 months. There is no specific follow-up due to the research.

Assessment criteria:

* Primary criteria: Neutrophil subtypes analysis based on co-expression of neutrophil function markers from a panel of 24 markers by flow cytometry.
* Secondary criteria: assessment of neutrophil sub-types present in the patient's saliva and study of the correlation within blood neutrophils, during periodontal health, gingivitis and periodontitis.

Eligibility Criteria:
Inclusion Criteria:

Common to all groups:

* Age: 3 to 12
* Patient affiliated to a social security program, beneficiary not covered by the AME.
* Legal representatives who speak and understand French well enough to be able to read and understand the study information.
* Legal representatives giving written consent for their child's participation in the study.

Specific:

Case Group:

* Trisomy 21 patient with gingival inflammation (subgroup 1)
* Trisomy 21 patient with healthy gingiva on intact periodontium with no history of periodontitis (subgroup 2)

Control Group: child meeting one of these criteria:

* Patient with psychomotor retardation with no known repercussions on the orofacial sphere or immunity, presenting gingival inflammation (subgroup 1)
* Patients with psychomotor retardation and no known repercussions on orofacial health or immunity, presenting gingival health on intact periodontium with no history of gingival inflammation (subgroup 2).
* Patients with no known general pathology and gingival inflammation (subgroup 3)
* Patients with no known general pathology and healthy gingiva on intact periodontium with no history of gingival inflammation (subgroup 4)

Exclusion Criteria:

Common to all groups:

* Patient having received antibiotic prophylaxis, antibiotic therapy or anti-inflammatory treatment in the 3 months prior to inclusion
* Patient included in another interventional research protocol or in a period of exclusion.
* Patient on AME
* Patients with a contraindication to the use of MEOPA:

  * Patients requiring pure oxygen ventilation
  * Intracranial hypertension
  * Unevaluated head trauma
  * New-onset, unexplained neurological abnormalities
  * Pneumothorax
  * Emphysema bubbles
  * Gas embolism
  * Diving accident
  * Abdominal gas distension, occlusion
  * Patient recently treated with ophthalmic gas (SF6, C3F8, C2F6)
  * Known, unsubstituted vitamin B12 deficiency

Specific to Trisomy 21 group:

- Patient with no genetic diagnosis