ESPE Abstracts

Background/aims: Temple syndrome (TS14) is an imprinting disorder caused by maternal uniparental disomy of chromosome 14 (UPD(14)mat), paternal deletion of 14q32 or by an isolated methylation defect. TS14 is considered a Prader-Willi-like (PWL) disorder and phenotypic features include pre- and postnatal growth retardation, hypotonia, feeding difficulties, precocious puberty, short stature and truncal obesity.

Methods: This study reviewed medical records of 15 patients with Temple syndrome who visited the Dutch Reference Center for Prader-Willi syndrome and PWl, from December 2018 to January 2022.

Results: The median (IQR) age of the patients was 9.02 (4.71; 12.47) years. Of the 15 patients, 9 had UPD(14)mat and 6 had an isolated methylation defect. The most common symptoms were intra-uterine growth retardation (IUGR) (100%), precocious puberty (100%), hypotonia (100%), small hands and feet (100%), joint hypermobility (67%), small for gestational age (SGA) birth (67%), tube feeding after birth (60%) and psycho-behavioral problems (53%). The median (IQR) IQ was 91.5 (85.7; 98.0) Most patients were enrolled in special education (54%) despite the fact that very few had intellectual disability. The median (IQR) fat mass SDS was 2.07 (1.85 to 2.5) and median (IQR) lean body mass SDS -1.8 (-2.5 to -1.22). There were no significant differences in characteristics between patients with a UPD(14)mat and an isolated methylation defect.

Conclusion: TS14 is a clinically recognizable disorder, but patients do present with variable symptoms. The 15 patients in the current study, share a distinct phenotype of IUGR, SGA birth, precocious puberty, hypotonia, tube-feeding after birth, and psycho-behavioral problems. In later childhood and adolescence, many of the patients became overweight. The neonatal phenotype of TS14 is very similar to the one of PWS and, in order to avoid delay in diagnosis, testing for TS14 should be considered in patients presenting with a PWS phenotype in infancy, and in patients that were born SGA and present with precocious puberty in later childhood. TS14 might be fairly underdiagnosed.