FaCD Online Syndrome Fact Sheet

Last updated: 24 Sep 2009

Name: Hereditary Mixed Polyposis syndrome type 2

Synonym: HMPS2

Mode of Inheritance: AD

Genes

BMPR1A, mapped to 10q22.3

Tumor features

colorectal adenomas
colorectal cancer
colorectal hamartomatous polyps
colorectal hyperplastic polyps
colorectal polyps
gastrointestinal polyps, juvenile type

Tumor features (possible)

thyroid cancer, papillary
Wilms' tumor (nephroblastoma)

Comment

Hyperplastic, adenomatous, juvenile-type polyps as well as mixed types and cases of colorectal cancer were reported by Cao et al [1] in a large Singapore family. Mean age at diagnosis of the polyps was 32.4 years.
Chea et al[2] subsequently reported 8 HMP families from Singapore in which they detected a total of 4 germline BMPR1A mutations. These families were characterized by hyperplastic and adenomatous polyps, but rarely juvenile type polyps. The authors also reported a case of Wilms tumor and papillary thyroid cancer associated with BMPR1A in these families. Chea et al suggest that BMPR1A should be the first gene to be tested in mixed polyposis families.

Clinically, HMPS II should presently be considered part of the heterogenous spectrum of mixed polyposis which also includes hyperplastic polyposis and hereditary mixed polyposis type type I.

References

[1] Cao X, Eu KW, Kumarasinghe MP, Li HH, Loi C, Cheah PY. Mapping of hereditary mixed polyposis syndrome (HMPS) to chromosome 10q23 by genomewide high-density single nucleotide polymorphism (SNP) scan and identification of BMPR1A loss of function. Journal of medical genetics 2006; 43(3):e13.
[2] Cheah PY, Wong YH, Chau YP, Loi C, Lim KH, Lim JF, Koh PK, Eu KW. Germline Bone Morphogenesis Protein Receptor 1A Mutation Causes Colorectal Tumorigenesis in Hereditary Mixed Polyposis Syndrome. Am J Gastroenterol. 2009 Sep 22. [Epub ahead of print]