Year : 1982 | Volume
: 30 | Issue : 4 | Page : 291--294
Effect of birth order and parental age on congenital ocular abnormality
LC Dutta, H Bhattacharjee
Deptt. of Ophthalmology, Medical College, Gauhati, India
L C Dutta
Dept of Ophthalmology, Medical College, Gauhati
|How to cite this article:|
Dutta L C, Bhattacharjee H. Effect of birth order and parental age on congenital ocular abnormality.Indian J Ophthalmol 1982;30:291-294
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Dutta L C, Bhattacharjee H. Effect of birth order and parental age on congenital ocular abnormality. Indian J Ophthalmol [serial online] 1982 [cited 2020 Apr 4 ];30:291-294
Available from: http://www.ijo.in/text.asp?1982/30/4/291/29453
Birth order effect is described in systemic diseases like mongolism congenital Pyloric Stenosis, Apert's Syndrome and several other diseases. Limited literature is available in birth order effect in ocular diseases. Murty 3 reported that 50% of the cases of congenital cataract are of the first birth order. Incidence ofmicrophthalmos, congenital corneal opacity and amblyopia is less in first born children than second, third and fourth ones 4 Few authors reported that parental age also modilies the incidence of some of the congenital and hereditary ocular disorders. "5161 In this study an attempt is made to find out if there is any statistically significant relation of birth order effect and parental age in the incidence of congenital abnormalities of the eye.
MATERIALS AND METHODS
129 patients attending the eye department of Gauhati Medical College having congenital abnormalities of the eye like cataract, huphthalmos, various grades of microphthalmos and colobomatous defects and some systemic congenital abnormalities having ocular lesions were examined. D-tailed family history and genetic tree were analysed in respect of parental age and birth order of the affected persons. Distribution of birth order and parental age at birth of these cases were determined and recorded. Corresponding data of persons with acquired ocular lesions caused by corneal ulcer, xerophthalmic, iridocyelitis and injury were compared. Chi-quare test was done to find out statistical significance using the formule:-
Where 0 stands for number of observed cases as E for number of expected cases.
[Table 1], shows the various types of congenital ocular abnormalities met within this study. In general, incidence of congenital abnormalities is seen to be more common in first to fourth birth order and it gradually declines there-after. There are 83 (64.3%) males and 46(35.7%) females. Various grades of microphthalmos viz. colobomatous microphthalmos, microphthalmos with cyst, pure microphthalmos and clinical anophthalmos was the commonest type of abnormality (35%).
Congenital lens abnormalities like cataract and eotopia lentis constituted 29% [Figure 1]. shows a comparison between the affected (with congenital ocular abnormalities) and unaffected members of the 108 families to which 129 cases belonged. [Figure 2]. shows that highest incidence of congenital cataract is in first birth order and its incidence drops down in the second children the incidence of various grades of microphthalmos is more common in 2nd, 3rd birth order. Birth order effect of 106 persons with various non-congenital diseases does not show any definite relationship. The result of Chi-squars test for varifying statistical significance showed P-value to be 0.50 which is towards positive significance. [Figure 3] shows the relation of prenatal age at birth of the child with frequency of congenital abnormalities. Maximum number of cases with congenital abnormalities were found where the parental age group was 28-35 years and maternal age group was 23-29 yrs. However due to non-availability of the parental age for total local population and due to small number of control cases, Chi-square test for statistical significance could not be done.
Literature regarding the incidence of congenital ocular abnormalities in Indian population is scanty. In an isolated study the incidence is reported to be 10.5 per 1000 of live births? Pathogenesis of the congenital ocular abnormalities may be due to environmental sporadic or hereditary chromosomal disorders. The results of this study indicates that more than 30% of congenital cataract cases are of first birth order and in subsequent birth orders the incidence drops down by about 50%. Congenital glaucoma usually occurs in children of second and 3rd birth order. According to published reports 4 the number of first-born children is large. This study shows that 10% of microphthalmos occurs in first born children.
Parental age modifies the incidence of some of the congenital and hereditary diseases older man have a slightly risk of producing new mutations in their reproductive cells though the exact physiological basis of this ageing effect on mutation is not known. It it postulated that advanced age of the mother at the time of conception is a probable cause of defects like Mongolism. Pathogenesis of several other diseases may be due to this factor. Our study shows that maximum number of congenital abnormalities occurs in the maternal age group of 23-29 years and parental age group of 28-35 years. However it could not be supported by statistical significance test. Nakijama et a1 reported that less mothers in their 20's and more in their 30's produced children with Microphthalmos and congenital Cataract.
Infection and malnutrition are the common causes of blindness in India. After successful implementation of the 20 year National programme for visual Empairment and Control of Blindness it is expected that congenital and hereditary diseases will be responsible for quite a high percentage of blindness at present about 20% of blindness is due to such diseases,. Hence finding of existance of birth order effect and parental age might provide some clue to the understanding of the pathogenesis of the congenital disease as well as suggesting possibility of controlling of such diseases by improvement of environmental conditions during pregnancy and by genetic counseling
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