Loss-of-function pathogenic variants in SMAD4 cause juvenile polyposis syndrome and we hypothesize that the gain-of-function pathogenic variants observed in Myhre syndrome may contribute to neoplasia in the patients reported herein.
In the proband, the analysis showed the presence of a truncating mutation in the SMAD4 gene (c.1213dupC, a variant previously associated with juvenile polyposis and Hereditary Hemorrhagic Teleangectasia).
Through this case report we aim to discuss the pathophysiology of juvenile polyposis syndrome (JPS), highlight what we believe to be a novel presentation of comorbid BMPR1A mutation and ASD and hypothesise that patients with BMPR1A mutation and JPS may be at risk of previously unrecognised cardiovascular complications analogous to the previous association of SMAD4JPS and cardiac abnormalities.
Patients with gastric juvenile polyposis and SMAD4 mutations are at a high risk of developing gastric cancer; hence, early gastrectomy should be considered.
The genetic variations can alter the structure and function of the BMPR1A gene that causes several diseases such as juvenile polyposis syndrome or hereditary cancer-predisposing syndrome.
The SMAD4 and BMPR1A genes that are involved in 50-60% of JPS cases have not been investigated in the ~ 20 published cases of NF1-associated JLIHMPs with the exception of the abovementioned patient with concomitant JPS and NF1.
Juvenile polyposis syndrome (JPS) may coexist with hereditary hemorrhagic telangiectasia (HHT) due to implication of the SMAD4 gene in a subset of both diseases.
Through this case report we aim to discuss the pathophysiology of juvenile polyposis syndrome (JPS), highlight what we believe to be a novel presentation of comorbid BMPR1A mutation and ASD and hypothesise that patients with BMPR1A mutation and JPS may be at risk of previously unrecognised cardiovascular complications analogous to the previous association of SMAD4 JPS and cardiac abnormalities.
The SMAD4 and BMPR1A genes that are involved in 50-60% of JPS cases have not been investigated in the ~ 20 published cases of NF1-associated JLIHMPs with the exception of the abovementioned patient with concomitant JPS and NF1.
Through germline multigene panel testing, we discovered the co-occurrence of Lynch syndrome due to a PMS2 mutation and juvenile polyposis syndrome due to a BMPR1A mutation in a young man with synchronous bladder and colorectal cancers and a family history of colorectal polyps.
One patient with mutations in both ENG and ACVRL1 genes was identified, as were two SMAD4-mutated patients suffering from the overlapping juvenile polyposis-HHT syndrome.
Our findings support that SMAD4 mutations carriers have symptoms of both HHT and JPS and that the frequency of PAVM and gastric involvement with polyps is higher than in patients with HHT or JPS not caused by a SMAD4 mutation.