We report a patient with Noonan syndrome with multiple lentigines (NSML) due to a PTPN11 (p.Thr468Met) mutation associated with hypertrophic neuropathy of lumbar plexus in an adult woman, initially referred for neuropathic pain.
A new examination of the patient and his similarly affected father, who was initially referred as healthy, led us to suspect LEOPARD syndrome, The diagnosis was then confirmed by the occurrence in both patients of a heterozygous mutation c.1403 C > T, p.(Thr468Met), of PTPN11.
Here we present a patient with severe, progressive neonatal HCM, elevated urinary catecholamine metabolites, and dysmorphic features in whom we identified a known LEOPARD syndrome-associated PTPN11 mutation (c.1403 C > T; p.T468M) and a novel, potentially pathogenic missense SOS1 variant (c.1018 C > T; p.P340S) replacing a rigid nonpolar imino acid with a polar amino acid at a highly conserved position.
Here we present a patient with severe, progressive neonatal HCM, elevated urinary catecholamine metabolites, and dysmorphic features in whom we identified a known LEOPARD syndrome-associated PTPN11 mutation (c.1403 C > T; p.T468M) and a novel, potentially pathogenic missense SOS1 variant (c.1018 C > T; p.P340S) replacing a rigid nonpolar imino acid with a polar amino acid at a highly conserved position.
Direct sequencing of the patients' genomic DNA revealed that all three had a consistent missense mutation [c.1403C > T (p.T468M)] in the PTPN11 gene, confirming LEOPARD syndrome with an atypical phenotype.
Direct sequencing of the patients' genomic DNA revealed that all three had a consistent missense mutation [c.1403C > T (p.T468M)] in the PTPN11 gene, confirming LEOPARD syndrome with an atypical phenotype.
Diverse driving forces underlie the invariant occurrence of the T42A, E139D, I282V and T468M SHP2 amino acid substitutions causing Noonan and LEOPARD syndromes.
Diverse driving forces underlie the invariant occurrence of the T42A, E139D, I282V and T468M SHP2 amino acid substitutions causing Noonan and LEOPARD syndromes.
Furthermore, we show that the recurrent LS-causing Y279C and T468M amino acid substitutions engender loss of SHP-2 catalytic activity, identifying a previously unrecognized behavior for this class of missense PTPN11 mutations.