Is there a significant trend in prevalence of consanguineous marriage in Tehran? A review of three generations

High rates of "atypical" single nucleotide polymorphism-based noninvasive prenatal screening results among consanguineous Arab American patients: A single center retrospective study

Noninvasive prenatal screening (NIPS), using placental cell-free DNA from a maternal blood sample, is currently the most sensitive and specific screening tool for detecting common fetal aneuploidies. The aim of this study was to compare the rates of "atypical" single nucleotide polymorphism (SNP)-based NIPS results and subsequent pregnancy outcomes between Arab American and non-Arab American patients. We conducted a retrospective cohort study of pregnant Arab and non-Arab American patients who had SNP-based NIPS performed between September 2018 and January 2021 at an urban health system in Michigan. The rate of "atypical" results and other perinatal outcomes were compared between groups using descriptive statistics. "Atypical" results due to multifetal gestations, either undisclosed or unknown at time of ordering, were excluded. Five thousand eight hundred and seventy-three patients underwent SNP-based NIPS: 771 (13.1%) were identified as Arab American, 5102 (86.9%) were non-Arab American, and 49 (0.8%) patients received "atypical" results. Arab patients represented only 13.1% of patients screened (771/5873) but had a significantly higher rate of "atypical" results than non-Arab American patients (17/771 [2.2%] vs. 32/5102 [0.6%]; p < 0.001). Of the 17 Arab patients with "atypical" results, 9 (52.9%) were in known consanguineous relationships. No major congenital anomalies or chromosomal aberrations were identified for any patients who had "atypical" results, and no significant differences in other perinatal outcomes were observed between Arab and non-Arab American patients. A better understanding of the association between consanguinity and "atypical" SNP-based NIPS results would aid in appropriate test selection and interpretation and may help physicians and genetic counselors provide better perinatal counseling and follow-up care for patients in consanguineous relationships.

Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum

BACKGROUND

Spinal muscular atrophy (SMA) could be classified as 5q and non-5q, based on the chromosomal location of causative genes. A rare form of non-5q SMA is an autosomal-recessive condition called spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME), phenotypically characterized by myoclonic and generalized seizures with progressive neurological deterioration. SMA-PME is a clinically heterogeneous disorder that arises from biallelic pathogenic variants in ASAH1 gene.

METHODS

Following clinical and primary laboratory assessments, whole-exome sequencing was performed to detect the disease-causing variants in three cases of SMA-PME from different families. Also, Multiplex ligation-dependent probe amplification (MLPA) was employed for determining the copy numbers of SMN1 and SMN2 genes to rule out 5q SMA.

RESULTS

Exome sequencing revealed two different homozygous missense mutations (c.109 C > A [p.Pro37Thr] or c.125 C > T [p.Thr42Met]) in exon 2 of the ASAH1 gene in the affected members of the families. Sanger sequencing of the other family members showed the expected heterozygous carriers. In addition, no clinically relevant variant was identified in patients by MLPA.

CONCLUSION

This study describes two different ASAH1 mutations and the clinical picture of 3 SMA-PME patients. In addition, previously reported mutations have been reviewed. This study could help to fortify the database of this rare disease with more clinical and genomic data.

Exploring the genetic etiology of drug-resistant epilepsy: incorporation of exome sequencing into practice

BACKGROUND

By affecting about 50 million people worldwide, epilepsy is considered a global concern in neurology. Intolerable enough, up to ¼ of all patients do not respond to antiepileptic drugs and have recurring seizures. Therefore, revealing the underlying etiology is quite demanding in a clinical context to improve diagnosis and disease management.

METHODS

Initially, 85 patients suspected of epilepsy underwent thorough clinical and paraclinical evaluation and 24 individuals with drug-resistant epilepsy entered the study. Using whole-exome sequencing, the genetic etiology of drug-resistant epilepsy was investigated and discerned whether this method could facilitate the management of drug-resistant epilepsy through personalized medicine. Eventually, functional annotation was performed and drug-gene interaction networks were constructed to find potential therapeutic targets.

RESULTS

We found eleven novel variants in various genes including IRF2BPL, ST3GAL3, and GPAA1, for which a few epilepsy-related variants are available in public databases. The overall diagnostic yield for likely pathogenic and pathogenic variants and the detection rate of novel variants were 25% and 84.6%, respectively. Based on the results, two patients were considered potential candidates for personalized medicine. The highest number of interaction with drugs was demonstrated for SCN1A, SCN2A, and GRIN2A genes.

CONCLUSIONS

This study highlighted the importance of consanguineous marriage in drug-resistant epilepsy and suggested the possibility of reduced penetrance and variable expressivity in some of the autosomal dominant cases. We also suggest that whole-exome sequencing could facilitate personalized management of drug-resistant epilepsy. Regarding drug-gene interactions, some genes such as SCN1A and SCN2A might serve as therapeutic targets in drug-resistant epilepsy.

Utilization of Whole Exome Sequencing in Non-Syndromic Premature Ovarian Failure: Ficolin-3 Gene Mutation in an Iranian Family

Background

Premature ovarian failure is a heterogeneous disorder, leading to early menopause. Several genes have been identified as the cause of non-syndromic premature ovarian failure (POF). Our aim was to explore the genetic defects in Iranian patients with POF.

Methods

We studied a family with three females exhibiting non-syndromic POF. WES was performed for one of the affected individuals after ruling out the presence of CGG repeat expansion at fragile X mental retardation 1 gene in the family. Sanger sequencing was used to confirm the candidate sequence variants in the proband, and screening of the detected mutation was performed for the other affected and unaffected members of the family.

Results

A homozygous frameshift mutation, c.349delC, was identified in ficolin-3 (FCN3) gene in the proband and two other patients. The parents and two healthy brothers were heterozygous for the mutation, and an unaffected sister was homozygous for wild type.

Conclusion

This is the first report of a mutation in FCN3 gene in a family with POF. Our findings can lead to the enhancement of genetic databases of patients with POF, specifically for families with high-risk background.

Assessment of the correlation between various risk factors and orofacial cleft disorder spectrum: a retrospective case-control study

Background

Orofacial clefts (OFCs) comprise a wide range of malformations, including cleft lip, cleft palate, and cleft lip with cleft palate, which can vary in terms of etiology, severity, and disease burden.

Objective(s)

This study aimed to evaluate the correlation between various risk factors and orofacial cleft disorder spectrum in newborns.

Study design

A total of 323 cases and 400 controls were enrolled in this study and evaluated in terms of the maternal history of abortion or miscarriage, child’s sex, maternal and paternal age, maternal history of systemic disease, history of medication therapy during pregnancy, birth order, consanguineous marriage, and complications during pregnancy.

Results

Analysis of the results suggested that consanguineous marriage, a maternal history of abortion/miscarriage, and complications during pregnancy could potentially increase the risk of OFCs in children (P < 0.05). However, the analyses revealed that the other variables could not potentially increase the risk of OFCs (P > 0.05).

Conclusion(s)

Multiple cofactors may simultaneously contribute to the formation of such abnormalities; therefore, a comprehensive, multidisciplinary care program is necessary to ensure a successful pregnancy period and the birth of a healthy newborn.

Type 1 diabetes genetic risk score discriminates between monogenic and Type 1 diabetes in children diagnosed at the age of <5 years in the Iranian population

AIM

To examine the extent to which discriminatory testing using antibodies and Type 1 diabetes genetic risk score, validated in European populations, is applicable in a non-European population.

METHODS

We recruited 127 unrelated children with diabetes diagnosed between 9 months and 5 years from two centres in Iran. All children underwent targeted next-generation sequencing of 35 monogenic diabetes genes. We measured three islet autoantibodies (islet antigen 2, glutamic acid decarboxylase and zinc transporter 8) and generated a Type 1 diabetes genetic risk score in all children.

RESULTS

We identified six children with monogenic diabetes, including four novel mutations: homozygous mutations in WFS1 (n=3), SLC19A2 and SLC29A3, and a heterozygous mutation in GCK. All clinical features were similar in children with monogenic diabetes (n=6) and in the rest of the cohort (n=121). The Type 1 diabetes genetic risk score discriminated children with monogenic from Type 1 diabetes [area under the receiver-operating characteristic curve 0.90 (95% CI 0.83-0.97)]. All children with monogenic diabetes were autoantibody-negative. In children with no mutation, 59 were positive to glutamic acid decarboxylase, 39 to islet antigen 2 and 31 to zinc transporter 8. Measuring zinc transporter 8 increased the number of autoantibody-positive individuals by eight.

CONCLUSIONS

The present study provides the first evidence that Type 1 diabetes genetic risk score can be used to distinguish monogenic from Type 1 diabetes in an Iranian population with a large number of consanguineous unions. This test can be used to identify children with a higher probability of having monogenic diabetes who could then undergo genetic testing. Identification of these individuals would reduce the cost of treatment and improve the management of their clinical course.

Genetics and genomic medicine in Iran

Attention has been focused on the field of genetics and genomics in Iran in recent years and some efforts have been enforced and implemented. However, they are totally not adequate, considering the advances in medical genetics and genomics in the past two decades around the world. Overall, considering the lack of medical genetics residency programs in the Iranian health education system, big demand due to high consanguinity and intraethnic marriages, there is a lag in genetic services and necessity to an immediate response to fill this big gap in Iran. As clarified in the National constitution fundamental law and re-emphasized in the 6th National Development Plan, the Iranian government authority is in charge of providing the standard level of health including genetic services to all Iranian individuals who are in need.

A review of the reproductive consequences of consanguinity

BACKGROUND

Consanguinity is the close union, sexual relationship or marriage between persons who have common biological ancestors usually up to about 2nd cousins. Contrary to general opinion consanguinity is quite common and is practiced worldwide. It is an important topic as while rates of consanguineous unions in certain society have decreased over time, rates have remained stable or increased in other societies with rates as high as 80.6% in some communities. Our aim was to conduct a review looking at general aspects of consanguinity and any published reproductive outcomes in literature. We also looked at possible future directions that could be relevant in the management of the consanguineous couple to help improve reproductive outcomes.

METHOD

We conducted a PUBMED, CINAHL, Web of Knowledge and Google Scholar search looking at articles on consanguinity. Consanguinity articles related to pregnancy and reproduction were searched using additional filters looking at our specific areas of interest. All relevant publications up to March 2015 were reviewed. Additional search for relevant articles pertaining to pre implantation genetic diagnosis for future directions in the management of the consanguineous couple was done. Most publications were found in books, on line articles and journals. Most were retrospective, population or cohort studies.

RESULT

Consanguinity is practiced by up to 10% of the world's population with rates ranging from 80.6% in certain provinces in the Middle East to less than 1% in western societies. It predates Islam and has been practiced since Old Testament times. The most commonly cited reason for consanguinity is sociocultural and socioeconomic although it is also more common in certain religions. In areas where rates of Consanguinity are reducing urban migration and increasing education rates are thought to be contributory. Congenital malformations have long been established to be higher in consanguineous couples above the background rate (4.5% Vs 1%).Due to "Founder effect" or a common ancestor, Consanguinity is most commonly associated with Inborn errors of metabolism most of which are autosomal recessive. Consanguinity increases the incidence of multifactorial disorders such as diabetes, cardiovascular disorders, obesity and certain types of cancers. These may in turn affect reproductive outcomes. It may also affect fertility rates. Pregnancy outcomes like increased pregnancy wastages and preterm labor have been reported with consanguinity. Other studies produced conflicting evidence on its effect regarding outcomes like hypertensive disorders of pregnancy and Intrauterine growth restriction.

CONCLUSION

Consanguinity continues to be practiced worldwide and in some countries rates are increasing. The main reason for the practice appears to be sociocultural and socioeconomic although religious beliefs is a contributory factor. The most significant effects on reproductive outcomes are mostly due to autosomal recessive inherited conditions and inborn errors of metabolism. It also significantly increases the inheritance of certain multifactorial disorders like diabetes which may indirectly affect reproductive outcomes. In the future with the completion of the study of the whole human Genome and current advances in Pre implantation Genetic diagnosis and screening it may be possible to mitigate some of the adverse reproductive outcomes associated with consanguinity.

Consanguinity Among Parents of Iranian Deaf Children

Background

It seems that there is a relationship between consanguinity and profound hearing loss but there is little data about the association of consanguinity and hearing loss in Iran.

Objectives

The aim of this study is to demonstrate the causes of profound bilateral sensorineural hearing loss among Iranian samples who are candidates for cochlear implantation.

Methods

This study was retrospective, analytical, and designed to collect information about profound hearing impaired cases referred to the Baqiyatallah Cochlear implantation center using enumeration. A total of 310 children with profound hearing impairments participated in this study. They were aged from 6 months to 4 years old. The study was done between January 2007 and April 2009. Chi-square tests were used to show whether there was any statistical difference between the incidence of marital consanguinity of their parents and the normal population.

Results

Sixty-five percent of those 310 children had parents who had married with their relatives. Of the 203 (65%) parents that had consanguineous marriages, 132 were first cousins, which includes the children of two brothers (37 [11.8%] patrilateral parallel cousins), the children of two sisters (38 [12.2%] multi-lateral parallel cousins), or the children of a brother and a sister (57 [18.3%] cross cousins). Fifty-four (17.4%) of the parents were second cousins and 17 (5.2%) were beyond second cousins. Also, hearing loss etiology was obvious in 237 (76.3%) of the patients with profound hearing loss but was unknown in 73 (23.7%). Hereditary was identified as the most common cause in 33% of the cases.

Conclusions

Our data demonstrated a 65% occurrence of consanguineous marriage among the parents of deaf children, which is statistically different from the percentage of consanguineous marriage among Iranian population (38%). This indicates an obvious relationship between severe hearing loss and consanguineous marriage.

A study of consanguineous marriage as a risk factor for developing comitant strabismus

Inheritance has an important role in the etiology of comitant strabismus. Consanguineous marriage is a leading factor in birth defects in which inheritance has a role. The aim of this study is to reveal if consanguineous marriage increases the risk of developing comitant strabismus. We included 461 patients who underwent primary surgery for comitant strabismus in Shiraz University Khalili Hospital (Fars province, southern Iran) between years 2003 and 2013 in our study. All the patients were living in Shiraz, Iran. Patients were categorized into the following 4 groups: (1) intermittent or constant exotropia, (2) infantile esotropia, (3) non-accommodative acquired esotropia, and (4) accommodative acquired esotropia. A total of 421 healthy children who were born in Shiraz, at the same period of time, were also studied as a control group. Presence and type of the consanguineous marriages were evaluated in the parents of the patients and control group by a questionnaire. Mean of inbreeding coefficient (α) was calculated in each group of patients and was compared with those of control group. The proportion of parental first cousin marriage was 37.7 and 23.5 % among patient and control groups. The mean of inbreeding coefficients (α) were 0.0236, 0.0283, 0.0288, and 0.0236 in four groups of the patients, respectively. The mean of inbreeding coefficient was 0.0263 in total patients, which was significantly higher than 0.0164 of control group (T = 5.27, df = 880, P < 0.001). Patients with non-accommodative acquired esotropia had the highest mean of inbreeding coefficient (α) (0.0288). It seems that recessive form of inheritance plays an important role in the etiology of comitant strabismus. Modified screening programs may be needed for earlier detection of strabismus in the offspring of consanguineous couples.

The effect of homozygous deletion of the BBOX1 and Fibin genes on carnitine level and acyl carnitine profile

Background

Carnitine is a key molecule in energy metabolism that helps transport activated fatty acids into the mitochondria. Its homeostasis is achieved through oral intake, renal reabsorption and de novo biosynthesis. Unlike dietary intake and renal reabsorption, the importance of de novo biosynthesis pathway in carnitine homeostasis remains unclear, due to lack of animal models and description of a single patient defective in this pathway.

Case presentation

We identified by array comparative genomic hybridization a 42 months-old girl homozygote for a 221 Kb interstitial deletions at 11p14.2, that overlaps the genes encoding Fibin and butyrobetaine-gamma 2-oxoglutarate dioxygenase 1 (BBOX1), an enzyme essential for the biosynthesis of carnitine de novo. She presented microcephaly, speech delay, growth retardation and minor facial anomalies. The levels of almost all evaluated metabolites were normal. Her serum level of free carnitine was at the lower limit of the reference range, while her acylcarnitine to free carnitine ratio was normal.

Conclusions

We present an individual with a completely defective carnitine de novo biosynthesis. This condition results in mildly decreased free carnitine level, but not in clinical manifestations characteristic of carnitine deficiency disorders, suggesting that dietary carnitine intake and renal reabsorption are sufficient to carnitine homeostasis. Our results also demonstrate that haploinsufficiency of BBOX1 and/or Fibin is not associated with Primrose syndrome as previously suggested.

Mutation analysis of the CYP21A2 gene in the Iranian population

BACKGROUND

Defects in the CYP21A2 gene cause steroid 21-hydroxylase deficiency, which is the most frequent cause of congenital adrenal hyperplasia. Forty four affected families were investigated to identify the mutation spectrum of the CYP21A2 gene.

METHODS

Families were subjected to clinical, biochemical, and molecular analyses. Allele-specific polymerase chain reaction amplification was used for eight common mutations followed by dosage analysis to exclude CYP21A2 deletions.

RESULTS

The most frequent mutations detected were gene deletions and chimera (31.8%). Other mutation frequencies were as follows: Q318X, 15.9%; I2G, 14.8%; I172N, 5.8%; gene duplication, 5.7%; R356W, 8%; and E6 cluster mutations, 2.3%. Direct sequencing of the CYP21A2 gene revealed R316X, P453S, c.484insT, and a change at the start codon. Different modules carried by patients were classified into five different haplotypes. The genotype phenotype correlation (positive predictive value) for group null, A, B, and C were 92.3%, 85.7%, 100%, and 0, respectively.

CONCLUSIONS

Methods used will be helpful for carrier detection and antenatal diagnosis, especially with inclusion of the multiplex ligation probe dependent amplification technique, which is easier for routine tests in comparison with other methods. Mutation frequencies indicate that Iranians are possible descendants of Asians and Europeans.

Clinical Application of Screening for GJB2 Mutations before Cochlear Implantation in a Heterogeneous Population with High Rate of Autosomal Recessive Nonsyndromic Hearing Loss

Clinical application of mutation screening and its effect on the outcome of cochlear implantation is widely debated. We investigated the effect of mutations in GJB2 gene on the outcome of cochlear implantation in a population with a high rate of consanguineous marriage and autosomal recessive nonsyndromic hearing loss. Two hundred and one children with profound prelingual sensorineural hearing loss were included. Forty-six patients had 35delG in GJB2. Speech awareness thresholds (SATs) and speech recognition thresholds (SRTs) improved following implantation, but there was no difference in performance between patients with GJB2-related deafness versus control (all P > 0.10). Both groups had produced their first comprehensible words within the same period of time following implantation (2.27 months in GJB2-related deaf versus 2.62 months in controls, P = 0.22). Although our findings demonstrate the need to uncover unidentified genetic causes of hereditary deafness, they do not support the current policy for genetic screening before cochlear implantation, nor prove a prognostic value.

The effect of consanguinity on congenital disabilities in the Kuwaiti population

Consanguinity has been shown to increase homozygosity and to reduce genetic variation in a group, which may protect against the expression of recessive genes that can lead to genetic disorders. Consanguineous marriages are practised widely in Kuwait. The major aim of this study is to delineate the association of consanguineous marriages with congenital disabilities in different Kuwaiti population subcultures. A total of 9104 married Kuwaiti females aged 15-79 years from different backgrounds were selected at ten primary health care centres from six governorates in Kuwait. Data were collected using a questionnaire and analysed with chi-squared tests. The data indicate significant differences in the occurrence of genetic diseases in consanguineous couples' offspring (4.88%) compared with those of non-consanguineous couples (4.13%) (p<0.002). The results also show significant differences in frequencies of genetic/environmental diseases in consanguineous couples' offspring (8.59%) compared with those of non-consanguineous couples (8.23%) (p<0.005). No significant differences between the two groups regarding environmental diseases were observed. A higher frequency of genetic diseases was found in first- (6.97%; p<0.001), second- (6.78%; p<0.001) and third-cousin (6.46%; p<0.022) couples' offspring compared with those of non-consanguineous couples. The frequency of congenital disabilities in the offspring of couples from consanguineous marriages (2.9%) is higher than that in the offspring of non-consanguineous marriages (2.3%). But this difference is not significant at the 0.05 level. First-cousin marriages have the highest frequency (3.5%) of congenital disabilities compared with other kinds of marriages (2.1-2.3%). Differences across groups are significant (p<0.036). Significant differences are found for first-cousin couples in both physical (2.37; p<0.042) and mental (0.74; p<0.037) disabilities compared with non-consanguineous couples. No significant differences were observed in deafness and blindness disabilities. The data show no significant differences between second- and third-cousin and non-consanguineous couples in physical, mental or deafness and blindness disabilities. There are no significant differences in the percentages of offspring with congenital disabilities in consanguineous and non-consanguineous marriages across sub-population groups for the total of four types of congenital disability.

PREVALENCE OF CONSANGUINEOUS MARRIAGES AMONG IRANIAN GEORGIANS

Consanguineous marriage – marriage between relatives – has received a great deal of attention as a potential risk factor for many adverse health outcomes. The present cross-sectional study was done in order to illustrate the prevalence and types of consanguineous marriages among Iranian Georgians living in Frydoonshahr (Isfahan province, central Iran). Data on consanguineous marriages were collected using a simple questionnaire. The total number of couples in this study was 646. Consanguineous marriage was classified by the degree of relationship between couples. First cousin marriages (14.2%) were the most common type of consanguineous marriages, followed by second cousin (7.0%), beyond second cousin (1.5%) and first cousin once removed (0.6%). The mean inbreeding coefficient (α) was calculated as 0.0104 for the population. The present study shows that the study population, as other Iranian populations, has a high level of consanguinity.