SUN-725 Clinical and Genetic Features of Families with Maternally Inherited Central Precocious Puberty

Abstract

Context: The clinical recognition of familial central precocious puberty (CPP) has significantly increased in the last years. This fact can be related to the recent descriptions of genetic causes associated with this pediatric condition, such as loss-of-function mutations of two imprinted genes (MKRN3 and DLK1). Inherited defects in both genes cause paternally inherited CPP. However, no genetic abnormality has been described in families with maternally inherited CPP so far. Objectives: To characterize the clinical and genetic features of several families with maternally inherited CPP. Setting and Participants: We analyzed clinical and genetic features of children with familial CPP. No brain MRI alterations were detected in the selected patients with CPP. MKRN3 and DLK1 pathogenic mutations were excluded. Whole-exome sequencing was performed in selected cases. Results: We studied 177 children from 141 families with familial CPP. Paternal inheritance was evidenced in 44 families (31%), whereas 58 (41%) had maternally inheritance. Indeterminate inheritance was detected in the remaining families. Maternally inherited CPP affected mainly female patients (69 girls and two boys). Thelarche occurred at mean age of 6.1 ± 1.9 years in this female group. Most of girls had Tanner 3 (41%) and Tanner 4 (35%) breast development at first evaluation. One boy had additional syndromic features (macrosomia, autism, bilateral eyelid ptosis, high arcade palate, irregular teeth and abnormal gait). The pedigree analysis of patients with maternally inherited CPP revealed the following affected family members: 42 mothers, 10 grandmothers, 11 sisters, 12 aunts, and 11 female cousins. Most of the families (41) had two affected consecutive generations, while eight families had three affected generations. No consanguinity was referred. Ongoing molecular analysis revealed two rare heterozygous variants in the boy with syndromic CPP and three affected family members with precocious menarche (mother, maternally half-sister, and maternally aunt): a frameshift deletion (p.F144fs) in MKKS; and a missense variant (p.P267L) in UGT2B4, which encodes a protein involved in estrogen hydroxylation and it was related to menarche timing in genome-wide association studies. Conclusions: Maternally inherited CPP was diagnosed mainly in girls, who had thelarche at mean age of 6 years old. Dominant pattern of inheritance was more prevalent, with direct maternal transmission in 72% of the studied families. New candidate genes might be implicated with maternally inherited CPP.