Clinical and cytogenetic features of a Potocki–Lupski syndrome with the shortest 0.25 Mb microduplication in 17p11.2 including RAI1

Potocki–Lupski syndrome (PTLS [MIM 610883]) is a recently recognized microduplication syndrome associated with 17p11.2. It is characterized by mild facial dysmorphic features, hypermetropia, infantile hypotonia, failure to thrive, mental retardation, autistic spectrum disorders, behavioral abnormalities, sleep apnea, and cardiovascular anomalies. In several studies, the critical PTLS region was deduced to be 1.3 Mb in length, and included RAI1 and 17 other genes. We report a 3-year-old Korean boy with the smallest duplication in 17p11.2 and a milder phenotype. He had no family history of neurologic disease or developmental delay and no history of seizure, autistic features, or behavior problems. He showed subtle facial dysmorphic features (dolichocephaly and a mildly asymmetric smile) and flat feet. All laboratory tests were normal and he had no evidence of internal organ anomalies. He was found to have mild intellectual disabilities (full scale IQ 65 on K-WPPSI) and language developmental delay (age of 2.2 year-old on PRESS). Array comparative genomic hybridization (CGH) showed about a 0.25 Mb microduplication on chromosome 17p11.2 containing four Refseq (NCBI reference sequence) genes, including RAI1 [arr 17p11.2(17,575,978–17,824,623) × 3]. When compared with previously reported cases, the milder phenotype of our patient may be associated with the smallest duplication in 17p11.2, 0.25 Mb in length.     

Arnold‐Chiari type 1 malformation in Potocki–Lupski syndrome

Potocki–Lupski syndrome (PTLS) is a genetic disorder that results from an interstitial duplication within chromosome 17p11.2. Children with PTLS typically present with infantile hypotonia, failure to thrive, and global developmental delay with or without major organ system involvement. Systematic clinical studies regarding growth, cardiovascular disease, and neurocognitive profiles have been published; however, systematic evaluation of central nervous system structure by magnetic resonance imaging (MRI) of the brain has not been reported. Herein, we describe three patients with PTLS who were found—in the course of routine clinical care—to have a type 1 Arnold‐Chiari malformation (CM‐1). This finding raises the question of whether the incidence of CM‐1 is increased in PTLS, and hence, if an MRI of the brain should be considered in the evaluation of all patients with this chromosomal duplication syndrome.     

Reciprocal Deletion and Duplication of 17p11.2-11.2: Korean Patients with Smith-Magenis Syndrome and Potocki-Lupski Syndrome

Deletion and duplication of the -3.7-Mb region in 17p11.2 result in two reciprocal syndrome, Smith-Magenis syndrome and Potocki-Lupski syndrome. Smith-Magenis syndrome is a well-known developmental disorder. Potocki-Lupski syndrome has recently been recognized as a microduplication syndrome that is a reciprocal disease of Smith-Magenis syndrome. In this paper, we report on the clinical and cytogenetic features of two Korean patients with Smith-Magenis syndrome and Potocki-Lupski syndrome. Patient 1 (Smith-Magenis syndrome) was a 2.9-yr-old boy who showed mild dysmorphic features, aggressive behavioral problems, and developmental delay. Patient 2 (Potocki-Lupski syndrome), a 17-yr-old boy, had only intellectual disabilities and language developmental delay. We used array comparative genomic hybridization (array CGH) and found a 2.6 Mb-sized deletion and a reciprocal 2.1 Mb-sized duplication involving the 17p11.2. These regions overlapped in a 2.1 Mb size containing 11 common genes, including RAI1 and SREBF.