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   Table of Contents      
ORIGINAL ARTICLE
Year : 1990  |  Volume : 38  |  Issue : 4  |  Page : 193-194

Genetic heterogeneity of Oguchi's disease


Human Genetics Laboratory, School of Life Sciences, Guru Nanak Dev University, Amritsar-143 005, India

Correspondence Address:
Jai Rup Singh
Human Genetics Laboratory, School of Life Sciences, Guru Nanak Dev University, Amritsar-143 005
India
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Source of Support: None, Conflict of Interest: None


PMID: 2086477

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  Abstract 

An analysis of the cases reported in Punjab, India, indicates the presence of genetic heterogeneity of Oguchi's disease, for which autosomal recessive inheritance has been documented earlier. The autosomal dominant inheritance pattern of this disease is associated with incomplete penetrance and a distinct sex bias towards females. This recognition is important for genetic counselling.


How to cite this article:
Singh JR. Genetic heterogeneity of Oguchi's disease. Indian J Ophthalmol 1990;38:193-4

How to cite this URL:
Singh JR. Genetic heterogeneity of Oguchi's disease. Indian J Ophthalmol [serial online] 1990 [cited 2019 Dec 8];38:193-4. Available from: http://www.ijo.in/text.asp?1990/38/4/193/25498


  Introduction Top


Oguchi's disease, first described by Oguchi in 1907, is characterized by congenital, bilateral and stationary type of nyctalopia [2],[9],[25] at times also wrongly reported as hemeralopia. [8] It is associated with structural anomalies of the retina and diffuse yellow or grey colouration of the fundus. The normal colour of the fundus returns only after 2-3 hrs in total darkness. This disease is considered to be rare. The first European case with Oguchi's disease was documented in 1927. [11] the first American case in 1939 [14] and the first Indian case in 1969. [28] It is known to be hereditary with autosomal recessive mode of inheritance [21] without any distinction being made in Type I, Type Ila or Type Ilb. However, an analysis of the cases reported in India indicates the presence of genetic heterogeneity in this disease.


  Comments and discussion Top


The report of 19 cases of Oguchi's disease by Singh et al, [29] of which 10 belong to one city and three to a neighbouring township, supports the contention of-the authors that this disease may not be as rare as it is supposed to be. But their observation that the in­heritance pattern of the disease is in conformity with that of autosomal recessive inheritance, as reported earlier in literature, appears to be incorrect. Their data are rather strongly in favour of autosomal dominant type of inheritance at least for their familial cases. These authors reported three families having ten affected in- dividuals distributed over two generatioons. Patients of two families exhibited Type I Oguchi's disease while that of the third family Type Ila. These three families are crucial, as all the individuals had been specifically ex­amined for this disease by ophthalmologists. It is impor­tant because in the absence of thorough fundus examination and observation of Mizuo's phenomenon, there is every likelihood of a wrong diagnosis. [29] En­quiries from one of these authors revealed that within each of these three families, there were some normal individuals but their exact number is not traceable now. [30] If we reduce the data of these authors into the pedigree format, it will become obvious that the familial cases reported by them are not autosomal recessive In autosomal recessive mode of inheritance for rare diseases, the major characteristic features are:

(i) A higher incidence of consanguinity.

(ii) Parents are usually normal while 25% of the off­spring is afflicted.

(iii) The probability of an affected homozygote marrying an heterozygote is extremely low

The reported three pedigrees [Figure - 1] reveal absence of consanguinity (as specifically mentioned by the authors). In two families (Nos. 2 and 3), the mothers are also similarlly affected and the number of affected in­dividuals is much more than the expected 25% for recessive inheritance even after giving the due conces­sion for some of the normal individuals reported in each sibship.

On the other hand, in autosomal dominant type of in­heritance for rare diseases, the characteristic features are:

(i) Affected individuals have at least one similarly af­fected parent except in cases of incomplete penetrance.

(ii) 50% of the sibs are likely to be affected.

(iii) No higher incidence of consanguinity.

All the three pedigrees are more or less in conformity with these characteristics. The family No. 1 most likely exhibits the presence of incomplete penetrance. The sex and distribution of the affected individuals in these pedigrees also rules out the operation of .X-linkage but highlights the presence of sex influence. In familial cases, out of 10 affected individuals, 8 are females while amongst 9 isolated' cases, 7 are males and only 2 females. The presence of 9 additional isolated cases without any familial associations coupled with the sig­nificant sex differences between the two categories points to the operation of some other factors in the isolated cases than dominant type of inheritance only.

Considering Oguchi's disease to be genetic in origin, there could be several explanations for the isolated cases. A few of these cases could be of the dominant type with incomplete penetrance where their relatives, having milder symptoms may have escaped detection. Some could be of autosomal recessive type as already reported in the literature. [21] But the confirmation of it is not possible in the absence of complete familial data. Another possibility is that some of these isolated cases may be new mutants. However, as the incidence of Oguchi's disease is considered to be very low, the probability of new mutations occurring in such a high frequency is very remote. Alternatively, this disease is not a rarity in this region as is generally believed. A higher incidence of Oguchi's disease has also been reported for Japan. [21]

The main characteristic feature of Oguchi's disease in the absence of complete fundus examination is congeni­tal stationary type of night blindness. Genetic heterogeneity for congenital stationary type of night blindness is obvious from the literature. For this purpose, autosomal dominant t e of inheritance has been fre­quently reported [3],[4],[10],[22] In addition, X-linked form in association with myopia has been recorded. [23],[24] A bias towards females, as seen in the presented pedigrees, has also been recorded for congenital stationary blind­ness by Francois et al, [10] who reported a family of three generations where all four affected individuals were females. Moreover, the presence of different modes of inheritance for the same clinical entity is well docu­mented, especially for ophthalmic disorders. Autosomal dominant and recessive types of corneal dystrophies [19],[32], cornea plana [7],[16], ectopic lentis [5],[20] retinoblastoma, [6],[17] dominant and X-linked types of megalocorneal, [26] autosomal dominant, recessive as well as X-linked types of congential cataracts [8],[27],[31] and retinitis pigmentosa [12],[13],[15] are some of the known ex­amples.

In light of these observations,it is clear that Oguchi's disease like many other congenital ophthalmic condi­tions exhibits genetic heterogenity and has two distinct modes of inheritance; autosomal dominant as well as autosomal recessive. The dominant type being as­sociated with incomplete penetrance and has a distinct sex bias towards females. This recognition of the genetic heterogeneity is important from the view point of proper genetic counselling.

 
  References Top

1.
Alaerts. L.. 1949, Bull. Soc. BeIg. Ophthal. 92, 322.  Back to cited text no. 1
    
2.
Caccamice.W.C., 1949, Bull. U.S. Army Med. Dep. 9.920.   Back to cited text no. 2
    
3.
Carrol, F. and Haig, C.. 1953, Arch. Ophthal. 50, 35.  Back to cited text no. 3
    
4.
DeJean, C. and Gazzenc, R.. 1949. Bull. Soc. Ophthal. France. 96. 96.   Back to cited text no. 4
    
5.
Falls, H.F. and Cotterman. C.W., 1943, Arch. Ophthal. 34, 610.   Back to cited text no. 5
    
6.
Falls. H.F. and Neel, J.V., 1951, Arch. Ophthal. 46, 367.   Back to cited text no. 6
    
7.
Forsius. H., 1961, Acta Ophthal. 39, 203.  Back to cited text no. 7
    
8.
Franceschetti. A. and Chome-Bercious, N.. 1951. Ophthalmologica 121. 185.  Back to cited text no. 8
    
9.
Francois, J., Verriest. G. and De Rouck. A.. 1956. Ophthalmologica 131.1,  Back to cited text no. 9
    
10.
Francois, J., Verriest, G. and De Rouck, A.. 1965, Amer. J. Ophthal. 59. 621.  Back to cited text no. 10
    
11.
Gouras, P. and Carr. R., 1965, Arch. Ophthal. 73, 646.   Back to cited text no. 11
    
12.
Heck. A.f.. 1963. Arch. Ophthal. 70, 143.  Back to cited text no. 12
    
13.
Heuscher-Isler, R., Gysin, W. and Hegner. H.. 1949, Ophthalmologica 118. 858.  Back to cited text no. 13
    
14.
Klein. B.A., 1939. Amer,J. Opththal. 22, 953  Back to cited text no. 14
    
15.
Kobayaski, F., 1960, Jap. J. Ophthal. 4.82.  Back to cited text no. 15
    
16.
Larsen, V. and Eriksen, A., 1949. Acta Ophthal. 27, 276.   Back to cited text no. 16
    
17.
Macklin, M.T.. 1959, Arch. Ophthal. 62, 842.   Back to cited text no. 17
    
18.
Marner, E., 1949. Acta Ophthal. 27, 537.   Back to cited text no. 18
    
19.
Maumanee, A., 1960, Amer. J. Ophthal. 50. 1114.   Back to cited text no. 19
    
20.
McKusick, V.A. 1955. Amer. J. Hum. Genet. 7. 189.  Back to cited text no. 20
    
21.
McKusick, V.A. 1966, Mendelian Inheritance in Man, Londor: William Heineman Medical Books Ltd, 219.  Back to cited text no. 21
    
22.
Nettleship, E. 1907, Trans. Ophthal. Soc. U.K. 27, 269.  Back to cited text no. 22
    
23.
Nettleship, E. 1.09, Trans. Ophthal. Soc. U.K. 29. 57   Back to cited text no. 23
    
24.
Nettleship. E. 1912, Trans. Ophthal. Soc. U.K. 32, 21.   Back to cited text no. 24
    
25.
Oguchi. C., 1912, Griefe Arch. Ophthal. 81, 109.   Back to cited text no. 25
    
26.
Riddell, W.J.B., 1941, Ann. Eugen, 11. 102.   Back to cited text no. 26
    
27.
Saebo. J., 1949, Brit. J. Ophthal. 33, 601.  Back to cited text no. 27
    
28.
Singh. D. and Singh, D., 1969, J All India Ophthal. Soc. 17,222.   Back to cited text no. 28
    
29.
Singh. D.Singh, D. and Bansal, D.C.1 977. Ind. J. Ophthal. 25. 1.   Back to cited text no. 29
    
30.
Singh D.. 1986, Personal Communication.   Back to cited text no. 30
    
31.
Stieren, E., 1907, Ophthal. Rec. 21, 234.   Back to cited text no. 31
    
32.
Turnip, R., Tisserand, M. Serane, J.. 1939, Arch. Ophthal.3. 109  Back to cited text no. 32
    


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