Un terzo dei casi di pubertà precoce vera presentano una familiarità con ereditarietà di tipo autosomico dominante

Many clinical observations show that precocious puberty may be in some cases familial: the pubertal pattern may be influenced by familial trend, such that families with one member with precocious puberty have a higher than normal probability of having another. However, up until now scientific support to this assumption remains sparse. There is only one study that has taken into account the pattern of trasmission of the familial cases of central precocious puberty (CPP) [9]. The aim of the present study is to identify a familiarity in central precocious puberty and to define the possible mode of inheritance of familial central precocious puberty. We also tried to understand if familial cases differ from sporadic ones in some features. Among the 110 children affected by CPP, 41 cases (37.3%) met the criteria for familial precocious puberty (FPP) while the remaining 69 cases of CPP were sporadic (62.7%) (SPP). An autosomal dominant inheritance was found in 24 cases (58.5%) of FPP; an autosomal dominant transmis-sion with incomplete, sex-dependent penetrance (39%) was found in 16 families; an autosomal recessive in-heritance was found in only 1 case (2.5%) of FPP. Regarding the clinical comparison between the two groups of patients, age at onset and age at diagnosis of FPP is not different from the one of SPP. The difference of SD-BMI between the two groups has resulted to be significant: girls affected by FPP seem have a higher BMI than SPP. SD-height, however, is not significantly different between the two groups so that we consider weight to be determinant in such a difference. This data gather with a higher maturity of bone age in FPP that could go along with overweight. In the SPP group, 14 out of 69 children (20.3%) presented some CNS anomalies. In the FPP group, we found some CNS anomalies in 7 out of 41 children (17.1%). In conclusion we suggest that a precocious sexual development has familial origin in 1/3 of cases, with an auto-somal dominant or an autosomal dominant inheritance with incomplete sex-dependent penetrance. Girls affected by familial forms of precocious puberty have higher BMI and higher bone maturity then girls af-fected by sporadic forms of precocious puberty have. The high prevalence of familial cases of precocious pu-berty in general population suggests that, when a child is diagnosed with precocious puberty, a careful inquiry of the young siblings and first-degree cousins regarding precocious puberty should be performed. Data collected from this study do not allow to exclude the necessity of prescribing a cerebral MRI also in familial cases of CPP.