Roles of insulin-like growth factor 1 receptor in growth regulation in 15q26 deletion and duplication syndrome

The 15q26 deletion and duplication syndromes are rare chromosome diseases with growth deviation and structural anomalies such as facial abnormality, cardiac malformation and hand/foot/skeleton malformations. Insulin-like growth factor 1 receptor (IGF1R), located on chromosome 15q26, is key for pre- and postnatal growth. The present study aimed to determine whether IGF1R serves as a key factor in growth regulation in 15q26 deletion and duplication syndromes. Patients with 15q26 deletions and duplications enrolled in the China Neonatal Genomes Project (CNGP) were recruited. A systematic review of 15q26 deletion and duplication cases was performed, followed by meta-analysis to evaluate the roles of IGF1R and three other genes [myocyte enhancer factor 2A (MEF2A), leucine-rich repeat kinase 1 (LRRK1) and nuclear receptor subfamily 2 group F member 2] involved in growth regulation. A total of 10 eligible patients from the CNGP, including seven with deletions and three with duplications, were identified. The literature search and screening yielded 78 patients with 15q26 deletions and 10 with 15q26 duplications. Clinical features observed in >70% of the patients in the deletion group were facial abnormalities, developmental delay, short stature and hand/foot/skeleton malformations, whereas the duplication group exhibited facial abnormality, hand/foot/skeleton malformation and speech development delay. In 15q26 deletion, three candidate genes were associated with an increased risk of short stature: IGF1R [odds ratio (OR): 8.43; 95% confidence interval (CI): 2.22-32.00], LRRK1 (OR: 100.00; 95% CI: 11.86-843.23) and MEF2A (OR: 32.21; 95% CI: 3.81-272.47). In 15q26 duplication, none of the candidate genes significantly affected tall stature. Using meta-analysis, the present study revealed that IGF1R is not the only key gene responsible for growth abnormalities in 15q26 deletion and duplication syndromes.