Table 4

Molecular basis of low penetrance retinoblastoma

Type of mutation

Number of LP families

Description of mutations and frequency ^a

Functional consequences

Regulatory

3

-198G>A (1/2)

-188G>T (1/2)

-149G>C (1/1)

Low expression of normal Rb protein

MS point mutations

12

R661W (8/20)

C712R (2/5)

W563L (1/1)

R787Q (1/1)

Partial inactivation of Rb protein

Inframe deletion

3

Del:N480 (1/1)

Del:E04

Del: E24–25

Partial inactivation of Rb protein

Splicing

10

607+1G>T (4/11)

862-10T>C (1/1)

539+1delG, del E05 (1/1)

2325+5G>A, del E:22 (1/1)

Q443P/del:E13 (1/1)

V654L/splice (1/2)

E732E/del E:21(1/2)

Alternative splicing and/or unessential exon skipping resulting in low expression or partial inactivation of Rb protein

NS point mutation

1

Q675X (1/1)

Alternative splicing involving the stop codon

^aRatio of mutations found in LP families vs. all mutations in the database is shown in brackets

Valverde et al. BMC Genetics 2005 6:53   doi:10.1186/1471-2156-6-53