Spontaneous growth in German children and adolescents with genetically confirmed Prader-Willi syndrome

Height and weight in children with Prader-Willi syndrome, diagnosed by stan dard clinical criteria, follow a specific developmental pattern resulting i n early childhood obesity, absent pubertal growth spurt and adolescent shor t stature. New molecular techniques (methylation analysis, fluorescence in situ hybridization) now allow the unequivocal diagnosis of Prader-Willi syn drome (PWS). We investigated the possibility of a bias in syndrome-specific growth standards based on clinically diagnosed patients by comparing these standards with new standards derived from 100 German patients with molecul arly confirmed PWS, none of whom had received a growth-promoting therapy. H eight centile curves of the German patients fall in the tall range of stand ards derived from American patients. This is mainly due to an elevation of the lower centile ranges in both sexes. When the height standards derived f rom German patients are compared to those of a large multinational cohort o f patients, 78% of whom were not confirmed by genetic testing, only minor d ifferences in the height centiles become apparent. The population backgroun d therefore does not appear to play a major role for the observed differenc es. In a marked proportion of patients a decreased sitting height/height ra tio is found. This was usually associated with scoliosis. Weight standards from our study group show that after 14 y of age German girls with PWS are heavier than their American counterparts. Standards for the body mass index of German patients of both sexes are increased over normal reference stand ards (p < 0.0001) and do increase with age (boys: p = 0.0038; girls: p = 0. 0004). PWS genotypes or sex had no apparent influence on Sos for height, we ight and body mass index. Conclusions: Because of the observed differences to other growth standards, use of the newly constructed centile curves is advocated in German patient s with molecularly confirmed PWS to avoid delay in the diagnosis of additio nal growth-compromising conditions.