Bleeding diathesis in Noonan syndrome

The Evaluation of Hematologic Screening and Perioperative Management in Patients with Noonan Syndrome: A Retrospective Chart Review

OBJECTIVES

To assess the potential impact of using screening recommendations for bleeding disorders in patients with Noonan syndrome on perioperative bleeding complications.

STUDY DESIGN

We performed a retrospective, single-site cohort study; patients were identified by query of the electronic medical record. All patients with a clinical diagnosis of Noonan syndrome over a 10-year period were included. Data on surgeries, hematologic evaluation, bleeding symptoms, and bleeding complications were extracted. Surgeries were graded as major or minor.

RESULTS

We identified 101 patients with Noonan syndrome, 70 of whom required surgery for a total of 164 procedures. Nine patients (9/70; 12.8%) had bleeding complications, occurring in those without comprehensive testing or perioperative intervention and undergoing major or dental surgery. Based on these findings, the risk of a bleeding complication for patients with Noonan syndrome who did not have comprehensive testing or perioperative intervention was 6.2% (95% CI 2.3%-10.1%), indicating the number needed to treat or screen would be 16 to prevent 1 bleeding complication (95% CI 9.9-43.9). The majority of patients had either no or incomplete evaluation (59 of 101; 58.4%).

CONCLUSIONS

With proper evaluation and management, the bleeding risk in patients with Noonan syndrome can be minimized. Efforts are needed to address the knowledge and implementation gap in this evaluation.

Evaluation of bleeding disorders in patients with Noonan syndrome: a systematic review

Background

Noonan syndrome (NS) is an autosomal dominant genetic condition that has a number of clinical features, including bleeding diathesis and a number of hematological abnormalities including clotting factor deficiencies, von Willebrand disease and abnormal platelet count/function.

Methods

We evaluated the frequency/types of bleeding disorders, and associated hematological laboratory findings, in patients with NS, using published data from 1965 to 2014.

Results

Of 45 studies identified, 31 included data for 428 patients with NS. Of these patients, 43% had reported bleeding, 26% had no reported bleeding and no bleed data was reported for 31%. Most patients (90%) had bleeding-related laboratory test abnormalities, but only 194 (45%) had a confirmed diagnosis of a specific bleeding disorder. Abnormal laboratory tests included: prolonged prothrombin time, activated partial thromboplastin time, and other platelet-related disorders. Of the 194 patients with a confirmed diagnosis of a specific bleeding disorder, 153 (79%) had single clotting factor deficiencies, von Willebrand disease or platelet-related disorders, and 41 (21%) had multiple deficiencies including platelet-related disorders.

Conclusion

As patients with NS can experience multiple bleeding disorders, including abnormal platelet function, clinical evaluations should be performed at diagnosis, after diagnosis, before any surgery is undertaken, and if patients become symptomatic.

Bleeding disorders in Noonan syndrome

Noonan Syndrome (NS) is a common genetic disease with multiple organ defects including bleeding disorders, which was last reviewed in 1997. Since then significant information has been acquired regarding bleeding problems in NS, specifically on the underlying genetics. Associations between mutated genes and bleeding disorders are reviewed along with prevalence and underlying etiologies. Between 50-89% of NS patients will have a bleeding disorder and since a significant number will require surgery it is important to identify which ones are at risk prior to their procedure. Recommendations regarding screening for bleeding disorders and their treatment are discussed.

Clinical and hematologic findings in Noonan syndrome patients with PTPN11 gene mutations

Reports on Noonan syndrome (NS) have documented multiple types of coagulation defects and bleeding diathesis, and a wide range of clinical presentations. Early studies suggested that a large proportion of NS patients have coagulation defects, whereas more recent reports indicate low rates of coagulopathy. The aim of this study was to evaluate phenotypic characteristics, PTPN11 gene mutations, and hematological and coagulation parameters in 30 clinically diagnosed cases of NS. One of the NS patients had a history of easy bruising; however, his hematological and coagulation tests were normal. None of the other patients had clinical coagulation problems. In the NS group, values for platelet count, activity of factors XI, XII, and protein C were significantly lower than the corresponding means for the control group. However, the results of coagulation tests in the NS group were diagnostically inconclusive and only one patient had clinical signs of coagulopathy. Interestingly, two NS patients had low protein C activity. One of these children had an A1517C mutation and transient myelodysplasia. The other patient had a C1528G mutation in exon 13 that has not been reported previously. Neither of these individuals experienced a thrombotic event or any complication during approximately 3 years of follow-up. For all patients clinically diagnosed with NS, a thorough history of coagulation issues should be taken and first-line coagulation testing should be done to evaluate for bleeding diathesis. However, if these assessments reveal nothing abnormal, complications related to coagulation are unlikely and extensive testing is unnecessary.