Abstract
Attempts to characterize the Noonan syndrome/phenotype have been frustrating and confusing since published descriptions have been incomplete and family members have rarely been studied.At the David Smith Malformations and Morphogenesis Meeting in August 1983, a workshop was held to try to define the clinical features of the Noonan syndrome. After reviewing cases brought by the conference participants and literature reports, a comprehensive checklist was compiled which represented the spectrum of features which should be considered in assessing an individual with Noonan phenotype. Subsequently, using this checklist, we have re-evaluated our own 39 patients and were able to identify two distinct groups: 23 sporadic cases and 16 familial cases (in 4 families). The four families were re-examined in detail in an attempt to delineate the intrafamilial variability and the natural history of familial cases, and to determine whether any specific phenotypic traits were pathognomonic or diagnostic.In these four families we could identify a characteristic facies which changed with age, and a range of heart lesions, stature and I.Q.In comparing the features found in our four families to our sporadic cases, heterogeneity was obvious. At least 4 subgroups of the Noonan phenotype could be defined. Certain features were more commonly associated with the sporadic cases than with the familial. In addition, within our four families there was an increased number of affected individuals when compared to unaffected (2:1), and an increased number of affected males compared to affected females (2:1). These abnormal ratios are similar to the segregation ratios found in previously reported families.
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Witt, D., Hall, J., Allanson, J. et al. DELINEATION OF VARIABILITY WITHIN FAMILIAL NOONAN'S SYNDROME. Pediatr Res 18 (Suppl 4), 308 (1984). https://doi.org/10.1203/00006450-198404001-01290
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DOI: https://doi.org/10.1203/00006450-198404001-01290