December 2001, Volume 51, Issue 12

Original Article

Perinatal Consanguinity: a Risk Factor for Developmental Delay in Pakistani Children

S. Ibrahim  ( Departments of Pediatrics, The Aga Khan University Hospital, Karachi. )
Z. Habib  ( Physical Therapy, The Aga Khan University Hospital, Karachi. )
I .S. Azam  ( Departments of Community Health Sciences, The Aga Khan University Hospital, Karachi. )
R. Ahmed  ( Departments of Medicine, The Aga Khan University Hospital, Karachi. )
S. Hyder  ( Departments of Medicine, The Aga Khan University Hospital, Karachi. )

Abstract

Objective: To investigate the association of parental consanguinity and delayed development in terms of gross motor, fine motor, speech and social aspects in their children.
Methods: One hundred and seventy seven children (age 15 days - 72 months) were evaluated for their developmental status utilizing the Denver Developmental Screening Test (DDST). An unmatched case-control study design was used. Case group consisted of 94 children and control group 83 children. Odds ratios were calculated for parental consanguinity and delay in gross and fine motor, speech and social development in their children, for cases and controls, utilizing Binary Multiple Logistic Regression Analysis. Acquired delay was excluded through detailed birth history in both cases and control group respectively.
Results: Univariate analysis showed high significant Odds ratios for all areas of developmental delay (viz, gross and fine motor, speech and social development), between cases and controls (p < .001). At the multivariate analysis level however, our results showed no increased risk of parental consanguinity on delayed gross and fine motor, speech and social development in their children.
Conclusion: Our results show no increased risk of parental consanguinity on delayed gross and fine motor, speech or social development (as measured by the DDST), in their children (JPMA 51 :41 8,2001).

Introduction

Consanguineous marriage is a predominant social and cultural tradition in many Asian countries. High prevalence rates have been especially reported from the Indo-Pak sub-continent1,2. An incidence of 37.1% and 31.1% consanguineous marriage has been documented in rural and urban Swat area in Pakistan respectively3. The same authors have reported significantly higher mortality rate in the offspring of first cousin marriages. Several Indian studies have also reported adverse effects of parental consanguinity and the incidence of mental retardation in their siblings4-6. Other deleterious consequences associated with parental consanguinity include increased morbidity and mortality in the neonatal, infant and early childhood period. A three-fold increase in post neonatal mortality and childhood morbidity has been reported in the offspring of consanguineous Pakistani parents in Birmingham7-9. Parental consanguinity has also been linked to growth retardation10, specific systemic disorders11 and congenital anomalies12.
Maiority of the studies addressing problems of consanguinity focused on mental retardation, morbidity and mortality issues. No work has been done in Pakistan on the specific effects of consanguinity and delayed gross and fine motor, speech and social development of children who belong to consanguineous parents. We were therefore interested in examining the relationship of parental consanguinity and delayed development (in terms of gross motor, fine motor, speech and social aspects), in their children. The following research questions were formulated:
1. Is there an association between parental consanguinity and delay in gross motor, fine motor, speech and social development in their children?
2. Is the degree of parental consanguinity (i.e. first cousin marriage) related to delay in gross motor, fine motor, speech and social development in their children?

Subjects and Methods

An unmatched case-control study of 177 children was conducted at the Aga Khan University Hospital (AKUH), Karachi, Pakistan. A total of 94 children (age 15 days - 72 months) with confirmation of delay in gross motor, fine motor, speech and social development were chosen as cases from the outpatient Pediatric Neurology Clinic. Similarly, a group of 83 typically developing children (age 15 days - 72 months) were selected as controls from the outpatient General Pediatric Clinic of the AKUH, during the same time period. The Denver Developmental Screening Test (DDST) was administered for diagnosing a case or control. This test has been widely used by health care providers to screen for developmental delays in many countries13. The DDST is appropriate for use in children £6 years of age. The Psychometric properties of DDST are detailed in the manual14. The DDST is used routinely both for screening and monitoring milestone progress at the outpatient pediatric clinic of the AKUH.
Procedures
The study was conducted over a nine-month period.
After a formal consent, the parents/guardians of the child were explained the purpose of the study, and were interviewed via a standard questionnaire. If any selected controls demonstrated a delay in gross motor, fine motor, speech or social development, (as measured by the DDST), they were excluded from the control group and enlisted as a case. Care was taken to exclude any acquired delay in gross motor, fine motor, speech or social development through acquired illness such as head trauma and meningitis via a detailed birth history both in the case and control groups respectively. Parental consanguinity was classified as presence or absence of consanguinity (i.e. yes or no), and further sub-classified as first cousin, second cousin, or no consanguinity for univariate analysis between cases and controls. Other variables included age (<18 months, sj8 months), gross motor, fine motor, speech and social delay (normal, delay), maturity (preterm, term, and post-term), cyanosis (yes, no), jaundice (yes, no), bodyweight (sga = < 2.5kg, aga = 2.5-3.5kg, iga = >3.5kg) and type of delivery (LSCS=low segment caesarian section, SVD = spontaneous  vertex delivery and lurceps).
The attending doctor administered the DDST to all children presenting to both the pcdiatric reurology and the general peditiuic clinics respectively. for either an initial or a folliw-up visit. Complctc evaluation of a child through the Dl)sT, therefore based on both thc parents’ history regarding their child\\\'s dev elopnient’al milestones and clinical examinati ion by the doctors at the time of presentation. Any child who was found to have a delay based on this assessment. in any one or all fur aspects of development (xii. gross motor, tine motor, and sociah. was classified ac developmentally delayed.
Data Analysis
Statistical package SPSS 10.0 for Windows was utilized for analysis. Descriptive statistics utilizing frequency table and measurcs of central tendency (M) and standard deviation (SD)] along with distribution curse for age groups. in cases and controls were analyzed. Binary Multipic Logistic Regression Analysis was utilized to calculate odds ratios (OR) ith 95% confidence intervals (Cl). As a first step, univariate analysis was computed to explore the effect of some factors (viz. age, consanguinity, type of delivers, cyanosis, jaundice, maturity and body weight) which were assumed to have a theoretictil bearing on delayed devdopment, between cascs and controls. Ihe univariate analysis also included the presence or absence of devlaved gross motor, tine motor, speech and social delay betwecn cases and controls. Odd ratios were were then calculatulated for grose motor, fine molor, speech and social delay stratified by consanguinity (yes, no), between cases and controls.
All the factors were assessed with the help of Chi¬square by comparing cases verses control, for each variable of interest, and OR with 95% Cl, were calculated. The reference group for each variable of interest was determined by the category with minimum level of potential risk of case and ic represented by number in 1 the tables. Independent samples Z-test was also performed for comparing the age of children between cases and controls.

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