Link Between Abnormal Bleeding and Coagulation Disorders in Noonan Syndromes (PlatNoon)

November 20, 2025 updated by: University Hospital, Bordeaux

Hemorrhagic Risk and Hemostasis Disorders in Noonan Syndrome and Related Conditions

Noonan syndrome is a relatively rare genetic disorder, affecting around 1 in every 1,000 to 2,500 children born. Patients often have a tendency to bleed more easily, particularly from the skin or mucocutaneous tissue (such as mouth or nose). Around half of all the patients are affected by bleedings. The causes of bleeding are variable : some are linked to platelet disorders, others to more complex coagulation problems. However, it is difficult to predict exactly which patients are at risk of severe bleeding, for example during surgery. This is why there are as yet no clear recommendations for preventing this risk before medical intervention. However, it is recommended that patients with Noonan syndrome consult a specialist to assess this risk. Unfortunately, the tests carried out are often unreliable in predicting this significant risk of bleeding. In this study, data from a large group of patients with Noonan syndrome, followed-up in different centers in France, will be studied. During a medical meeting as part of their regular follow-up, a medical doctor assessed their tendency to bleed using a standardized questionnaire (standardized ISTH-BAT score). These results will be compared with the biological tests also performed during their medical follow-up. The aim is to better understand whether these tests are useful in predicting the risk of bleeding. Ultimately, this could help practicians to better anticipate surgical or medical interventions in these patients, and limit bleeding-related risk.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Noonan syndrome (NS) is an autosomal dominant genetic disorder, with an estimated prevalence of 1 in 1,000 to 2,500 births/year. Patients with NS have a cutaneous-mucosal hemorrhagic diathesis, with a prevalence estimated at 46% in a large meta-analysis. The most frequently reported abnormalities are those of primary hemostasis (thrombocytopenia, thrombopathy and Willebrand's disease), as well as those of coagulation, but the correlation between symptomatology and hemostatic disorders is unclear. As a result, there are no specific recommendations in terms of intraoperative hemorrhagic risk prevention, due to a lack of knowledge of the real hemorrhagic risk in these patients, who are particularly exposed to invasive procedures. The PNDS recommends that patients be referred to a haemostasis specialist for assessment of bleeding risk, which entails the performance of investigations that are often not very predictive of bleeding risk. Interpretation of these results with regard to bleeding risk therefore remains unsolved. It is against this backdrop that the aim of this study is to retrospectively collect the bleeding diathesis of a national cohort of patients with SN, using a standardized ISTH-BAT score, performed in the context of a specialized hemostasis consultation by a physician from one of the centers involved in this study. The hemorrhagic diathesis will be compared with the results of the hemostasis exploration performed as part of their follow-up (routine care). This study will make it possible to assess the value of a hemostasis study in predicting the risk of bleeding in these patients.

Study Type

Observational

Enrollment (Estimated)

100

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Patient with noonan syndrome

Description

Inclusion Criteria:

  • All patients with SN, regardless of age
  • Patient/parental guardians informed of the study
  • Patient/legal representative not opposed to the use of their/the child's data
  • Person affiliated or benefiting from a social security scheme

Exclusion Criteria:

- Adults protected by law (guardianship, curatorship or safeguard of justice)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Noonan Syndrome (SN)
Cohort of SN patients meeting study eligibility criteria
Other: Reuse of routine clinical and biological data
Reuse of routine clinical and biological data

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
ISTH-BAT haemorrhagic score
Time Frame: At first clinical visit in the referent center (retrieved retrospectively at inclusion visit)
The ISTH-BAT standardized questionnaire uses 14 items to assess the severity of cutaneous-mucosal, cerebral, articular and per- or post-operative haemorrhagic symptoms
At first clinical visit in the referent center (retrieved retrospectively at inclusion visit)
Willebrand factor
Time Frame: At first clinical visit in the referent center (retrieved retrospectively at inclusion visit)
The Willebrand factor will be obtained from biological tests (in percentage of controls mean value)
At first clinical visit in the referent center (retrieved retrospectively at inclusion visit)
Platelet function
Time Frame: At first clinical visit in the referent center (retrieved retrospectively at inclusion visit)
Platelet function will be obtained from biological tests (in percentage of controls mean value)
At first clinical visit in the referent center (retrieved retrospectively at inclusion visit)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University Hospital, Bordeaux

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

January 1, 2026

Primary Completion (Estimated)

January 1, 2027

Study Completion (Estimated)

January 1, 2027

Study Registration Dates

First Submitted

July 22, 2025

First Submitted That Met QC Criteria

November 20, 2025

First Posted (Actual)

December 2, 2025

Study Record Updates

Last Update Posted (Actual)

December 2, 2025

Last Update Submitted That Met QC Criteria

November 20, 2025

Last Verified

November 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CHUBX 2024/96

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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