Parental consanguinity among patients with schizophrenia in a rural community of South India: A clinical and genetic investigation

BACKGROUND

Studies from certain regions of the world indicate that consanguineous marriages are a risk factor for the development of schizophrenia in offspring. However the evidence is inconsistent partly due to methodological limitation of which hospital based recruitment contributing to significant bias. The studies from the Indian subcontinent, is scarce, where rates of consanguinity is high.

METHODS

The schizophrenia patients living in a geographically defined rural south Indian community and randomly selected controls dwelling in the same community sharing sociocultural, economic and lifestyle factors were recruited. They were assessed for parental consanguinity using the clinical interviews as well as DNA-based estimates. The latter was conducted by calculating the coefficient of inbreeding 'f'. A participant was considered to have consanguineous parentage if his/her parents shared a common ancestor no more remote than a great-great-grandparent, corresponding to DNA-based estimates of 'f' ≥ 0.0156.

RESULTS

The rates of parental consanguinity assessed by clinical interview were comparable in both groups (Cases: 10.71 %, Controls: 7.25 %; χ² = 0.493, p = 0.4825). However, DNA-based rates of parental consanguinity showed that 'f' was significantly higher among cases than controls (Mann-Whitney U = 11315.5; p = 0.022). Seventy-five cases (62.5 %) and 108 control participants (48.6 %) had 'f' ≥ 0.0156 (χ² = 6.008; p = 0.014). The results were consistent across different quality control measures.

CONCLUSION

Schizophrenia is associated with higher parental consanguinity, suggesting a role for multiple recessive risk alleles in its etiology. Replication in future studies in diverse settings would add further strength to this.

[Association between consanguinity with the ocular congenital abnormalities in Togo]

OBJECTIVES

To investigate the possibility of an association between parental consanguinity and the occurrence of congenital ocular abnormalities.

MATERIALS AND METHODS

A retrospective cross-sectional study was carried out over 3 years, from January 2016 to December 2018, in the pediatric ophthalmology unit of the University Hospital Campus of Lomé (Togo). It included children with congenital ocular abnormalities. Age, gender, geographic origin (city or urban area, village or rural area), degree of consanguinity of parents and types of congenital ocular abnomalities were the variables of study. Odds Ratio (OR) and logistic regression were used to investigate the correlation between parental consanguinity and the occurrence of congenital ocular abnormalities. A P-value of<0.05 was considered statistically significant.

RESULTS

Among the 103 patients with congenital ocular abnormalities, there were 60 (58.2%) males and 43 (41.8%) females. The mean age of the patients was 16 months, range 1 month-5 years. Patients born to consanguineous parents were 26.2% (27) of the total population. Of these 27 patients, 25 (92.6%) were born to second-cousin marriages and 24 (88.89%) came from a rural area. Parental consanguinity was correlated with developmental abnormalities of the globe (OR=37.50; 95% CI_: [4.46-314.80]; r=3.62; P=0.00), sclerocornea (OR=13.04; 95% CI: [1.39-122.54]; r=2.57; P=0.02) and corneal dystrophy (OR=9.37; 95% CI: [0.93-94.36]; r=2.24; P=0.02).

CONCLUSION

Our study suggests the existence of a correlation between parental consanguinity and the occurrence of congenital ocular abnormalities.

Can parental consanguinity be a risk factor for the occurrence of nonsyndromic oral cleft?

BACKGROUND

The cleft lip with or without palate is the most common congenital craniofacial anomaly, presenting prevalence that varies between different ethnicities. It presents a complex and multifactorial etiology which involves genetic and environmental factors. Regarding family history, some studies have observed a significant association among parental consanguinity and orofacial clefts.

AIMS

To investigate if there is an association between parental consanguinity and the occurrence of oral cleft in the offspring.

STUDY DESIGN

Retrospective, cross-sectional, quantitative case-control study.

SUBJECTS

Case group - parents of subjects with nonsyndromic oral cleft (n = 746). Oral cleft was classified in the following group: cleft lip only - CLO (complete or incomplete, unilateral or bilateral); complete cleft lip and palate - CLP (unilateral or bilateral); and, cleft palate only - CPO (complete or incomplete). Control group - parents of subjects without clefts or other anomalies (n = 502), totaling 1248 subjects.

OUTCOME MEASURES

Fisher's exact test was used to compare the consanguinity rates observed between the two groups (p < 0.05 for statistically significant differences).

RESULTS

A positive consanguinity rate of 2.68% was observed in the case group and 0.79% in the control group. This difference found between the groups was statistically significant (p = 0.02). The most frequent degree of kinship in cases of consanguineous marriages, in both groups, was between first cousins. The most frequent types of clefts in the offspring were also the cleft palate only and the cleft lip only.

CONCLUSION

In the study population, parental consanguinity was associated with the occurrence of nonsyndromic oral cleft, and may be considered an isolated risk factor in this population.

Genetic epidemiology of stuttering among school children in the state of Tamil Nadu, India

PURPOSE

Stuttering is a fluency disorder with a worldwide prevalence of 1%. Reports on the epidemiology of stuttering in India are limited. Our primary goal was to examine the prevalence of the disorder among school children. The study also aimed to examine risk factors associated with severity and the impact of parental consanguinity in stuttering.

METHOD

Children from 97 schools in the State of Tamil Nadu, India were screened. Extensive speech characterization, epidemiological details and three-generational pedigrees were collected for 180 probands. The genetic basis of stuttering was examined using the analysis of genealogical index of families (GIF), kinship group and sibling recurrence risk (SRR) measures. Regression analysis and chi-square tests were performed to test the association of risk factors with severity of the disorder.

RESULTS

Among the 74,544 school children screened, the prevalence of stuttering was found to be 0.46%. Pedigree analysis revealed a positive family history in 101 (56%) probands; overall familial incidence was 11%. We observed an overall male-favored sex ratio (4:1). Familial aggregation (GIF = 442.60, p-value <0.001) and sibling recurrence risk ratio (K_s = 0.197, SD = 0.041) was high among consanguineous families. Severity of stuttering was strongly associated with gender and moderately associated with age at onset.

CONCLUSION

The prevalence of stuttering in Tamil Nadu is estimated for the first time in this study. High familial incidence, familial aggregation and sibling recurrence risk ratio point to the presence of a genetic basis. Familial aggregation was high among consanguineous families although consanguinity did not seem to play a role in severity.

Regional differences of Turkey in risk factors of newborn hearing loss

OBJECTIVE

The aim of this study was to discover Turkish regional differences in the risk factors of newborn hearing loss.

METHOD

A multi-centered retrospective design was used. A total of 443 children, registered to the national newborn hearing screening programme, with bilateral hearing loss, from five different regions of Turkey, were evaluated in terms of the types of hearing loss, the degree of hearing loss, the types of risk factors, parental consanguinity, age at diagnosis and age of auditory intervention, respectively.

RESULTS

There was no significant difference in the prevalence of hearing loss between regions (χ² = 3.210, P = 0.523). Symmetric Sensorineural Hearing Loss (SSHL) was the most common type of HL in all regions (91.8%). Profound HL was the most common degree of HL in all regions (46.2%). There were statistically significant differences between regions in terms of types of HL (χ² = 14.151, P = 0.000). As a total, 323 (72.9%) of subjects did not have any risk factors. There were statistically significant differences between regions in terms of the types of risk factors (pre, peri and post-natal) for SSNHL (χ² = 16.095, P = 0.000). For all regions, the age of diagnosis was convenient with the JCIH criteria. However the age of hearing aid application was prolonged in some regions. There were statistically significant differences between regions in terms of the age of diagnosis (χ² = 93.570, P = 0.000) and the age of auditory intervention (χ² = 47.323, P = 0.000). The confounding effects of gender, age of diagnosis, age of hearing aids applications, HL in the family, types of risk factors for HL on SSNHL were detected.

CONCLUSION

To reach the goal of a high quality newborn hearing screening, there is a need to develop an evidence-based standard for follow up guideline. In addition, risk factors should be re-evaluated according to regional differences and all regions should take their own precautions according to their evidence based data.