Mosaic Variegated Aneuploidy Syndrome and Noonan Syndrome in the Same Family.

INTRODUCTION: Mosaic variegated aneuploidy syndrome 2 (MVA2) and Noonan syndrome (NS) are 2 genetic disorders with overlapping clinical features, including intrauterine growth retardation, dysmorphic features, and heart defects. Whereas NS is a well-known congenital entity, MVA2 is rare, and only a few cases have been reported in the literature.

CASE PRESENTATION: We report on the molecular findings in 3 patients with short stature phenotypes from the same family. By considering the clinical overlap between the patients, a common cause for the small stature was assumed in the beginning, but by whole exome analysis (WES) it turned out that the phenotypes were caused by different pathogenic variants in CEP57 and PTPN11 , respectively. As a result, both MVA2 and NS occurred in the same family.

CONCLUSION: As our example shows, the parallel occurrence of pathogenic alterations in different genes in the same family constitutes a challenge for the interpretation of WES data and has to be considered. The diagnostic workup illustrates the need for a careful anamnesis and molecular documentation in affected and healthy family members. The knowledge on the different molecular causes underlying the features of the affected family members is the basis for personalised therapeutic managements and can avoid unnecessary burden and even contraindicated therapies; while in patients with NS carrying PTPN11 variants growth hormone treatment leads to height increase, patients with MVA2 carrying CEP57 probably do not benefit from it.