|Year : 1983 | Volume
| Issue : 4 | Page : 443-445
Influence of heredity on ocular malformation
LC Dutta, H Bhattacharjee
Department of Ophthalmology, Gauhati Medical College, Gauhati, India
L C Dutta
Deptt. of Opthalmology, Gauhati Medical College, Gauhati, Assam
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Dutta L C, Bhattacharjee H. Influence of heredity on ocular malformation. Indian J Ophthalmol 1983;31:443-5
127 cases of various colobomatous defects of the globe, 47 cases of congenital cataracts and 8 cases of congenital glaucoma were investigated to find out the influence of heredity on these conditions.
| Materials and methods|| |
18472 cases from eye out patient department of Gauhati Medical College Hospital were screened out for colobomatous defects of the globe, congenital cataracts and congenital glaucoma, In the first interview all cases and/or their attendents were elaborately interrogated specially with reference to the presence of similar and any other form of congenital abnormality in their family. In the second and subsequent sittings all the available family members (paternal and maternal side) upto three generations were examined clinically and family tree was recorded in the conventional way. Standard statistical and biometric calculations were adopted for determination of made of inheritance i.e. Chisquare test was used for testing autosomal dominant inheritance, X-linked dominant inheritance, recessive and intermediate X-chromosomal inheritence. Weinderg's method was used for autosomal recessive inheritance. During determination of mode of inheritance possibility of selective fecundation, intrauterine mortality and insufficient penitrance of the trait being disregarded.
| Observations|| |
[Table - 1] shows various specific congenital ocular abnormalities met within this study,
its incidence being 0.9%).
It shows that maximum cases of congenital ocular abnormalities were sporadic in occurence. 7.02% cases of colobomatous defects, 8% cases of congenital cataract and 37.5% cases of congenital glaucoma were having positive heredity.
Amongst the colobomatous defect one family each of aniridis and isolated typical colobema of the iris and three cases of colobematous microphthalmes had autosomal dominant inheritance. In rest four families of colobomatous microphthalmos, involvement was found in the several members of the same sibship while their parents and offsprings of the married affected members were normal.
Majority cases of congenital cataracts were suffering from total congenital cataracts (60%), next frequent variety was zonular cataract (26%). Three cases of total cataract had autosomal dominant inhet itance and one family of zonular cataract had recessive inheritance.
In two families of congenital glaucoma. inheritance was recessive and in one family, two children (one male and one female) of same sibship were affected while their ancesters were normal.
| Discussion|| |
Majority cases of congenital ocular abnormalities are sporadic in occurence without any definite aetiological factors. Only approximately 10% cases are genetically determined and a few cases are totally due to envrionmental factors. Interaction between latter two factors is also stressed. Genetically determined congenital malformations are due to mutation either of autosomes or of sex chromosomes and again it may be single gene mutation chromosomal abnormality or variation in the amount of regulatory D.N.A. Such a mutant gena (fresh or old) is transmitted from one to next generations as a dominant or recessive trait according to capacity of expressivity. The present study is an effort to determine the influence of heredity and made of inheritance on certain major veraties of blinding congenital ocular abnormalities, as in modern world still to day congenital and hereditary diseases are greate problem while infactious and other dieases are showing a dowanward trend due to affective medical approach.
We found 8°%o of congenital cataract are genetically determined but the same incidence in western literature is 25 to 26%., Again instead of zonular cataract ssub the most frequent variety of congenital cataract found in this study was total cataract which requires early medical attention. Transmission pattern of total cataract is found to be autosomal dominant and in zonular cataract it is recessive. These type of transmission are reported earlier.,
Aetiologic factors of congenital glaucoma is heredity and inheritance is recessive. Exogenous factors even ocular neoplasm may give rise to congenital glaucoma. We found recessive inheritance in two families and in the rest of the families children of one sibships were affected; it may be due to fresh mutation or lack of penetrance of the gens. 62.5% cases of our observation is sporadic without any other associated, ocular pathology.
Colobomatous defects of the globe were the major blinding ocular malformation found in this study (127 out of 180 cases) and majority of them are spreading nature (92.80%); Gifford also reported this fact. Our observation on dominant inheritance of aniridia, isolated typical coloboma of the iris and colobomatous microphthalmos is similar to the reports already described in the litera ture.,, In four families it occurs as an isolated anomaly in some members of same sibship without involvement of ancestors and descendents. In these cases also there is definite heredity the nature of which could not be determined. Colobomatous ocular defects may occur with various chromosomal abnormalities like klinefelter's syndrome C-D Trisomy with D-D Translocatict D-Trisomy etc, but facility for such sophesticated investigations were lacking in our study.
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[Table - 1]