9p deletion syndrome-like in a girl with a 9p insertion on chromosome 2 without 9p deletion

Partial deletions of 9p have been reported as a clinically recognizable syn¬drome characterised by the variable association of intellectual disability, speech delay, hypotonia, cardiac anomalies and dysmorphisms. We report a 3 years old girl with midface hypoplasia, downslanting palpe¬bral fissures, teeth agenesis and teeth fusions. Language was not acquired. At birth, severe neonatal hypotonia and patent ductus arteriosus were pre¬sent. Phenotype was consistent with the clinical diagnosis of “9p deletion syndrome” (OMIM#158170), with uncommon features such as bilateral ca¬taract (diagnosed at 5 months), chronic constipation, high pain threshold and poor temperature control. Karyotype analysis showed an apparent 9p deletion. Array-CGH (60K Agilent) demonstrated a 2q microdeletion (600 Kb, from 166,993,501 to 167,602,904, NCBI Build 37/hg19) with normal dosage of chromosome 9. Subsequent FISH analysis revealed a 9p22.1p24.3 insertion in chromosome 2q [46,XX,ins(2;9)(q24.3;p22.1p24.3)dn]. The 2q microdeletion involved only two genes: SCN9A and SCN7A. SCN9A recessive mutations cause congenital insensitivity to pain. SCN7A is not associated with human disease, and in mouse is likely to be a sodium-level sensor of body fluids in the brain. SCN9A haploinsufficiency may sup¬port the clinical observation of the patient high pain threshold and the poor temperature control. We are verifying the presence of a second mutation on the remaining allele. Assuming that the 2q deletion cannot account for the whole phenotype, we speculate that a critical gene/regulatory region key for the “9p deletion syndrome” is located in the 9p breakpoint(s). This pati¬ent deserves future studies that may help to refine 9p critical region.