The First Vietnamese Patient of LEOPARD Syndrome due to a PTPN11 Mutation: A Case Report and Review of the Literature

LEOPARD syndrome is a rare congenital anomaly that involves several organs. Patients with this syndrome develop multiple lentigines resembling a leopard’s hide. LEOPARD is an acronym of the major features constituting the syndrome including lentigines, electrocardiographic conduction defects, ocular hypertelorism, pulmonary valve stenosis, anomalies of genitalia, retardation of growth, and deafness. The syndrome is rare, and only 200 cases have been reported yet worldwide. We present the case of an 8-year-old female patient who visited the Ho Chi Minh City Hospital of Dermato-Venereology because of multiple brownish-black “dots” on her face and body. On examination, she also showed abnormalities in the maxillofacial bones, vertebrae, shoulders, sternum, and teeth, as well as deaf-mutism and growth retardation, which are typical of LEOPARD syndrome. Genetic analysis revealed a PTPN11 gene mutation in this case. To the best of our knowledge, this is the first case of LEOPARD syndrome reported in Vietnam.

Leopard syndrome: the potential cardiac defect underlying skin phenotypes

LEOPARD syndrome (OMIM #151,100) caused by a germline PTPN11 mutation are characterized as multisystemic anomalies and variable marked phenotypes such as multiple lentigines and cafe´-au-lait spots, electrocardiographic conduction abnormalities, ocular hypertelorism/obstructive cardiomyopathy, pulmonary stenosis, abnormal genitalia, retardation of growth, and deafness. Phenotype overlap complicates clinical discrimination within RASopathies, making the diagnosis of LEOPARD more confusing and challenging. Besides, LEOPARD patients do not usually present with all these typical clinical features, increasing the possibility of underdiagnosis or misdiagnosis.Herein, we report a case of LEOPARD syndrome in a patient who only presented with pigmented skin spots and was initially diagnosed with multiple acquired melanocytic nevi. Subsequent pathological examination confirmed the diagnosis of multiple lentigines rather than melanocytic nevi. A genetic study showed a germline PTPN11 (Tyr279Cys) mutation and raised the suspicion of LEOPARD syndrome. A subsequent ECG examination detected potential cardiac defects and confirmed the diagnosis of LEOPARD. We considered that the potential damage of other systems underlying the skin multiple lentigines should not be ignored. The diagnosis of LEOPARD syndrome in an early stage before cardiac damage has reached a serious and irreversible stage can be meaningful for patients to fully understand the potential risks, complications and prognosis of the disease and to take appropriate precautions to prevent the potential risk of cardiac damage.

LEOPARD syndrome

LEOPARD syndrome with multiple lentigines (cardiomyopathic lentiginosis) is a rare, genetically predetermined disease with autosomal dominant inheritance. Prevalence of this syndrome is unknown. One of pathognomonic clinical manifestations of this syndrome is the presence of multiple lentiginous pigment spots all over the body. The most common cardiac manifestation (approximately 80%) is myocardial hypertrophy. We presented a rare clinical case of detecting LEOPARD syndrome with multiple lentigines in a 32-year old female patient with major manifestations evident as pronounces morpho-functional alterations, myocardial hypertrophy, and heart rhythm disorders.

P0-Related Protein Accelerates Human Mesenchymal Stromal Cell Migration by Modulating VLA-5 Interactions with Fibronectin

P0-related protein (PZR), a Noonan and LEOPARD syndrome target, is a member of the transmembrane Immunoglobulin superfamily. Its cytoplasmic tail contains two immune-receptor tyrosine-based inhibitory motifs (ITIMs), implicated in adhesion-dependent signaling and regulating cell adhesion and motility. PZR promotes cell migration on the extracellular matrix (ECM) molecule, fibronectin, by interacting with SHP-2 (Src homology-2 domain-containing protein tyrosine phosphatase-2), a molecule essential for skeletal development and often mutated in Noonan and LEOPARD syndrome patients sharing overlapping musculoskeletal abnormalities and cardiac defects. To further explore the role of PZR, we assessed the expression of PZR and its ITIM-less isoform, PZRb, in human bone marrow mesenchymal stromal cells (hBM MSC), and its ability to facilitate adhesion to and spreading and migration on various ECM molecules. Furthermore, using siRNA knockdown, confocal microscopy, and immunoprecipitation assays, we assessed PZR and PZRb interactions with β1 integrins. PZR was the predominant isoform in hBM MSC. Migrating hBM MSCs interacted most effectively with fibronectin and required the association of PZR, but not PZRb, with the integrin, VLA-5(α5β1), leading to modulation of focal adhesion kinase phosphorylation and vinculin levels. This raises the possibility that dysregulation of PZR function may modify hBM MSC migratory behavior, potentially contributing to skeletal abnormalities.