In contrast, Allikmets et al.
19 identified 13 mutant
alleles of the
ABCR gene in 16% (26/167) of patients
affected with AMD, suggesting that heterozygous missense
ABCR mutations could lead to late-onset macular
degeneration. The relevance of
ABCR missense mutations in
atrophic forms of AMD has been questioned by some
investigators.
20 21 22 Nevertheless, based on our data, we
can speculate that heterozygous
ABCR missense mutation may
be responsible for AMD, whereas heterozygous mutation
s truncating
ABCR may lead to a different but close phenotype,
late-onset FFM. Furthermore, previous descriptions of FFM inherited as
autosomal dominant traits strongly support this
hypothesis.
23 24 In our patient, we could not determine
the mode of inheritance of the disease. Indeed, his maternal
grandmother, who died at age 92, had loss of central vision (no
ophthalmologic data available), whereas his parents, who died at ages
74 and 72, did not mention any visual impairment. Moreover, findings in
fundus examination and FA of his two sons were normal, without pigment
epithelium atrophy, retinal flecks, or dark choroid. However, analysis
of the
ABCR gene revealed that the youngest, aged 38, had
inherited the deleterious mutation. Considering the age of onset of the
proband, we cannot exclude that macular dystrophy would appear later in
life.