Correspondence

Genetics of Colorectal Cancer

N Engl J Med 2003; 348:2361-2362June 5, 2003

Article

To the Editor:

Lynch and de la Chapelle (March 6 issue)1 emphasize the screening of high-risk patients who have a mutation in the adenomatous polyposis coli (APC) gene or who have one or more first-degree relatives with familial adenomatous polyposis. However, the importance of ophthalmic examination in screening for and diagnosis of familial adenomatous polyposis is not noted. Congenital hypertrophy of retinal pigment epithelium is the most prominent extracolonic manifestation of familial adenomatous polyposis and is present in about 90 percent of patients.2-4 This condition can be identified by noninvasive methods even in infants and young children by simple fundus examination with the pupils dilated. A combined approach involving the detection of an APC mutation and detection of congenital hypertrophy of retinal pigment epithelium for presymptomatic diagnosis of familial adenomatous polyposis is highly recommended.5

Wai Man Chan, M.R.C.P., F.R.C.S.
Chi Pui Pang, D.Phil.
Dennis S.C. Lam, F.R.C.S., F.R.C.Ophth.
Chinese University of Hong Kong, Kowloon, Hong Kong
dennislam@cuhk.edu.hk

5 References

1. 1

   Lynch HT, de la Chapelle A. Hereditary colorectal cancer. N Engl J Med 2003;348:919-932
   Full Text | Web of Science | Medline

2. 2

   Pang CP, Fan DS, Keung JW, et al. Congenital hypertrophy of the retinal pigment epithelium and APC mutations in Chinese with familial adenomatous polyposis. Ophthalmologica 2001;215:408-411
   CrossRef | Web of Science | Medline

3. 3

   Valanzano R, Cama A, Volpe R, et al. Congenital hypertrophy of the retinal pigment epithelium in familial adenomatous polyposis: novel criteria of assessment and correlations with constitutional adenomatous polyposis coli gene mutations. Cancer 1996;78:2400-2410
   CrossRef | Web of Science | Medline

4. 4

   Lam DSC, Kwok SPY, Kwok AKH, Liew CT, Lau JWY, Pang CC. Incidence and predictive value of congenital hypertrophy of retinal pigment epithelium in Chinese familial adenomatous polyposis patients. Chin Med J (Engl) 1998;111:278-281
   Web of Science | Medline

5. 5

   Pang CP, Lam DS. Differential occurrence of mutations causative of eye diseases in the Chinese population. Hum Mutat 2002;19:189-208
   CrossRef | Web of Science | Medline

To the Editor:

In Table 3 of the review article by Lynch and de la Chapelle, microcephaly is listed as one of the phenotypic features of the Bannayan–Ruvalcaba–Riley syndrome. In fact, patients with this syndrome have macrocephaly1 (with normal-size ventricles). Typically, their birth weight is greater than 4 kg and their birth length above the 97th percentile, but their final height as adults is within the normal range.2 In addition, 50 percent of the patients have hypotonia, delayed gross motor or speech development, or mental retardation.2 In about 60 percent of the patients, a myopathic process affecting the proximal muscles is present.2

Karen W. Gripp, M.D.
A.I. duPont Hospital for Children, Wilmington, DE 19803
kgripp@nemours.org

2 References

1. 1

   Gorlin RJ, Cohen MM Jr, Condon LM, Burke BA. Bannayan-Riley-Ruvalcaba syndrome. Am J Med Genet 1992;44:307-314
   CrossRef | Web of Science | Medline

2. 2

   Jones KL. Smith's recognizable patterns of human malformation. 5th ed. Philadelphia: W.B. Saunders, 1997.