Case Report: Identification of microduplication in the chromosomal 2p16.1p15 region in an infant suffering from pulmonary arterial hypertension

This study reports the first case of a patient with chromosomal 2p16.1p15 microduplication syndrome complicated by pulmonary arterial hypertension (PAH). A female infant was admitted to the hospital suffering from dyskinesia and developmental delay, and conventional echocardiography revealed an atrial septal defect (ASD), which was not taken seriously or treated at that time. Two years later, preoperative right heart catheterization for ASD closure revealed a mean pulmonary artery pressure (mPAP) of 45 mmHg. The mPAP was reduced, and the condition was stabilized after drug therapy. A genomic copy number duplication (3×) of at least 2.58 Mb in the 2p16.1p15 region on the paternal chromosome was revealed. Multiple Online Mendelian Inheritance in Man (OMIM) genes are involved in this genomic region, such as BCL11A, EHBP1, FAM161A, PEX13, and REL. EHBP1 promotes a molecular phenotypic transformation of pulmonary vascular endothelial cells and is thought to be involved in the rapidly developing PAH of this infant. Collectively, our findings contribute to the knowledge of the genes involved and the clinical manifestations of the 2p16.1p15 microduplication syndrome. Moreover, clinicians should be alert to the possibility of PAH and take early drug intervention when facing patients with 2p16.1p15 microduplications.

Microduplication in the 2p16.1p15 chromosomal region linked to developmental delay and intellectual disability

Background

Several patients with the 2p16.1p15 microdeletion syndrome have been reported. However, microduplication in the 2p16.1p15 chromosomal region has only been reported in one case, and milder clinical features were present compared to those attributed to 2p16.1p15 microdeletion syndrome. Some additional cases were deposited in DECIPHER database.

Case presentation

In this report we describe four further cases of 2p16.1p15 microduplication in four unrelated probands. They presented with mild gross motor delay, delayed speech and language development, and mild dysmorphic features. In addition, two probands have macrocephaly and one a congenital heart anomaly. Newly described cases share several phenotype characteristics with those detailed in one previously reported microduplication case.

Conclusion

The common features among patients are developmental delay, speech delay, mild to moderate intellectual disability and unspecific dysmorphic features. Two patients have bilateral clinodactyly of the 5th finger and two have bilateral 2nd-3rd toes syndactyly. Interestingly, as opposed to the deletion phenotype with some cases of microcephaly, 2 patients are reported with macrocephaly. The reported cases suggest that microduplication in 2p16.1p15 chromosomal region might be causally linked to developmental delay, speech delay, and mild intellectual disability.