Consanguineous marriages, pearls and perils: Geneva International Consanguinity Workshop Report

The utility of exome sequencing in diagnosing pediatric neurodevelopmental disorders in a highly consanguineous population

Exome sequencing (ES) has been utilized in diagnosing children with neurodevelopmental manifestations, this study aimed to investigate the utility of ES in children within a highly consanguineous population that presented with neurodevelopmental complaints. A retrospective chart review was performed for 405 children with neurodevelopmental complaints who have had ES and were evaluated in multiple centers in the United Arab Emirates over a four-year period. Within the cohort of 405 children, consanguinity was reported in 35% (144/405). The primary clinical presentations were developmental delay/cognitive impairment, distinctive facial features, hypotonia, seizures, and weakness. The diagnostic yield was 57% (231/405). Novel variants were identified in 54% (125/231) of positive cases. Within the positive cases, specific treatment was available in 6% (13/231) and copy number variants (CNV) were reported in 3% (8/231) of cases. In eight children, variants in genes that have not yet been linked to human disease that could potentially be the cause of the observed phenotype "candidate genes" were identified. ES was utilized effectively within this cohort with a high diagnostic yield and through the identification of novel gene variants, CNVs, candidate genes and secondary findings as well as the alteration of the treatment plan in cases where treatment was available.

An ESHG-ESHRE survey on the current practice of expanded carrier screening in medically assisted reproduction

STUDY QUESTION

What is the current practice and views on (expanded) carrier screening ((E)CS) among healthcare professionals in medically assisted reproductive (MAR) practices in Europe?

SUMMARY ANSWER

The findings show a limited support for ECS with less than half of the respondents affiliated to centres offering ECS, and substantial variation in practice between centres in Europe.

WHAT IS KNOWN ALREADY

The availability of next-generation sequencing, which enables testing for large groups of genes simultaneously, has facilitated the introduction and expansion of ECS strategies, currently offered particularly in the private sector in the context of assisted reproduction.

STUDY DESIGN, SIZE, DURATION

A cross-sectional survey evaluating practice and current views among professionals working in MAR practice in different European countries was designed using the online SurveyMonkey tool. The web-based questionnaire included questions on general information regarding the current practice of (E)CS in MAR and questions on what is offered, to whom the test is offered, and how it is offered. It consisted mostly of multiple-choice questions with comment boxes, but also included open questions on the respondents' attitudes/concerns relevant to (E)CS practice, and room to upload requested files (e.g. guidelines and gene panels). In total, 338 responses were collected from 8 February 2022 to 11 April 2022.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The online survey was launched with an invitation email from the ESHRE central office (n = 4889 emails delivered) and the European Society of Human Genetics (ESHG) central office (n = 1790 emails delivered) sent to the ESHRE and ESHG members, and by social media posts. The survey was addressed to European MAR centres or gamete banks and to centres located in non-European countries participating in the European IVF-monitoring Consortium. Two reminder emails were sent. After exclusion of 39 incomplete responses received (e.g. only background information), 299 respondents from 40 different countries were included for analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

Overall, 42.5% (127/299) of respondents were affiliated to centres offering ECS. The perceived responsibility to enable prospective parents to make informed reproductive decisions and preventing suffering/burden for parents were the main reasons to offer ECS. A single ECS panel is offered by nearly 45% (39/87 received answers) of the centres offering ECS, 25.3% (22/87) of those centres offer a selection of ECS panels, and 29.9% (26/87) offer whole exome sequencing and a large in silico panel. Different ranges of panel sizes and conditions were included in the ECS panel(s) offered. Most of the respondents (81.8%; 72/88 received answers) indicated that the panels they offer are universal and target the entire population. Pathogenic variants (89.7%; 70/78 received answers), and to a lesser extent, likely pathogenic variants (64.1%%; 50/78 received answers), were included in the ECS report for individuals and couples undergoing MAR with their own gametes. According to 87.9% (80/91 received answers) of the respondents, patients have to pay to undergo an ECS test. Most respondents (76.2%; 61/80 received answers) reported that counselling is provided before and after the ECS test. Preimplantation genetic testing, the use of donor gametes, and prenatal diagnostic testing were the three main reproductive options discussed with identified carrier couples. The main reason, according to the respondents, for not offering ECS in their centre, was the lack of professional recommendations supporting ECS (52.5%; 73/139 received answers) and the high cost for couples or reimbursement not being available (49.6%; 69/139). The challenges and moral dilemmas encountered by the respondents revolved mainly around the content of the offer, including the variants classification and the heterogeneity of the panels, the counselling, and the cost of the test.

LIMITATIONS, REASONS FOR CAUTION

Although the total number of respondents was acceptable, the completion rate of the survey was suboptimal. In addition, the heterogeneity of answers to open-ended questions and the ambiguity of some of the answers, along with incomplete responses, posed a challenge in interpreting survey results. It is also plausible that some questions were not easily understood by the respondents. For this reason, response and non-response bias are acknowledged as further limitations of the survey.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this survey could aid in identifying potential challenges or areas for improvement in the current practice of ECS in the MAR field and contribute to the discussion on how to address them. The results underline the need to stimulate a more knowledge-based debate on the complexity and the pros and cons of a possible implementation of ECS in MAR.

STUDY FUNDING/COMPETING INTEREST(S)

All costs relating to the development process were covered from European Society of Human Reproduction and Embryology and European Society of Human Genetics funds. There was no external funding of the development process or manuscript production. A.C. is full-time employee of Juno Genetics. L.H. declared receiving a research grant during the past 36 months from the Netherlands Organisation for Health Research and Development. She has also participated in a Health Council report of the Netherlands on preconception carrier screening and collaborated with the VSOP Dutch Genetic Alliance (patient umbrella organization on rare and genetic disorders). L.H. and C.v.E. are affiliated with Amsterdam University Medical Centre, a hospital that offers ECS in a non-commercial setting. R.V. received honoraria for presentations from Merck Academy and is unpaid board member of the executive committee of the Spanish Fertility Society. The other authors had nothing to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Consanguinity in northwest Pakistan: evidence of temporal decline

Pakistan has a high burden of hereditary and congenital anomalies and their incidence rate almost doubles against the background of parental consanguinity. Consanguineous unions (CU) are customary in Pakistan and deeply rooted socio-cultural norms favour CU. This study aimed to elucidate the determinants and temporal change in CU in four northwestern populations of Pakistan. In a cross-sectional study, data on marital union types, bio-demographic factors, and paternal consanguinity were collected from 6,323 ever-married individuals in four districts of northwest Pakistan: Haripur, Muzaffarabad, Mansehra, and Shangla. We used descriptive statistics and multivariable logistic regression analysis. The CU were calculated to be 55%, and inbreeding coefficient F (ICF) was estimated to be 0.029. Eight factors, including district, rural origin, age of husband, occupational group of husband, literacy of husband, parental consanguinity, exchange marriage, and extended family type, were found to be significant predictors of consanguinity in the multivariable logistic regression analysis. The rate of consanguinity decreased significantly in the younger age categories of individuals. The rate of CU was seen to be declining over time and in marriages that started 'before 1980' and 'after 2010', respectively, and there was a decline in ICF from 0.030 to 0.027. These analyses also showed that the literacy rate improved, the average age at marriage increased, and the frequency of exchange marriages decreased over time. This study employs a sizable first-hand dataset to demonstrate a lowering CU rate in northwest Pakistan. It is anticipated that the burden of inherited and congenital anomalies may likely to diminish in the study populations along with the fall in ICF.

Unbiased phenotype and genotype matching maximizes gene discovery and diagnostic yield

PURPOSE

Widespread application of next-generation sequencing, combined with data exchange platforms, has provided molecular diagnoses for countless families. To maximize diagnostic yield, we implemented an unbiased semi-automated genematching algorithm based on genotype and phenotype matching.

METHODS

Rare homozygous variants identified in 2 or more affected individuals, but not in healthy individuals, were extracted from our local database of ∼12,000 exomes. Phenotype similarity scores (PSS), based on human phenotype ontology terms, were assigned to each pair of individuals matched at the genotype level using HPOsim.

RESULTS

33,792 genotype-matched pairs were discovered, representing variants in 7567 unique genes. There was an enrichment of PSS ≥0.1 among pathogenic/likely pathogenic variant-level pairs (94.3% in pathogenic/likely pathogenic variant-level matches vs 34.75% in all matches). We highlighted founder or region-specific variants as an internal positive control and proceeded to identify candidate disease genes. Variant-level matches were particularly helpful in cases involving inframe indels and splice region variants beyond the canonical splice sites, which may otherwise have been disregarded, allowing for detection of candidate disease genes, such as KAT2A, RPAIN, and LAMP3.

CONCLUSION

Semi-automated genotype matching combined with PSS is a powerful tool to resolve variants of uncertain significance and to identify candidate disease genes.

Assessing Students' Knowledge and Attitudes Regarding the Risks and Prevention of Consanguineous Marriage: A Cross-Sectional Online Survey

Background

Several studies indicate a correlation between consanguinity and genetic disorders, congenital malformations, harm to reproductive health, and increased child mortality.

Objective

To assess students' knowledge and attitudes about risks and prevention of consanguineous marriage.

Methods

Demographic details of the participants and data on knowledge and attitudes concerning the risks and prevention of consanguineous marriage were obtained using an online self-administered questionnaire. The factors associated with good knowledge and attitude toward consanguineous marriage were investigated by logistic regression analysis.

Results

A total of 667 participants enrolled in the study. The average knowledge score about consanguineous marriage risk and prevention was 78.6% with a 95% confidence interval (CI) [77.3, 79.8], and the average attitude was 79.7% with a 95% confidence interval (CI) [79, 80.6]. A better knowledge score was observed in older participants (OR 1.01; 95% CI 1.004-1.024), females (OR 1.69; 95% CI 1.48-1.94), participants with parental history of consanguinity (OR 1.33; 95% CI 1.17-1.52), participants with family history of consanguineous marriage (OR 5.18; 95% CI 2.19-7.10), and participants with family history of inherited disease (OR 1.52; 95% CI 1.25-1.86).

Conclusion

In general, the overall level of knowledge and attitudes toward consanguineous marriage risk and prevention was good among university students. To efficiently control and manage the adverse health impacts associated with consanguineous marriage, there is an urgent need to develop and implement evidence-based counseling and screening programs for consanguineous marriage that would significantly reduce the number of at-risk marriages.

Uptake rate of carrier screening among consanguineous couples

OBJECTIVE

To quantify the uptake rates of Carrier Screening (CS) in consanguineous couples and compare this rate to that of non-consanguineous couples.

METHODS

We performed a matched case control study of 82 consanguineous couples seen at Rutgers-Robert Wood Johnson Medical school who were offered carrier screening between January 1, 2012 and October 10, 2022. We then matched each consanguineous female patient to a non-consanguineous female control patient who was also offered CS at the time of their genetic counseling appointment. A 2 × 2 contingency table analysis was used to compare rates of acceptance and declination between the consanguineous and non-consanguineous groups.

RESULTS

The overall acceptance rate among consanguineous couples was 82.9%, whereas the overall acceptance rate among non-consanguineous couples was 56.1%. After statistical analysis, consanguineous couples were significantly more likely to accept CS as compared to non-consanguineous couples (OR = 3.801, 95% CI; p < 0.0001). We also report the carrier couple rates and individual carrier statistics between these two groups.

CONCLUSION

This study supports the idea that consanguineous couples are more likely to pursue CS and have a higher carrier couple yield.

Accelerated MEN2A in homozygous RET carriers in the context of consanguinity

BACKGROUND

Homozygous mutations, 2 identical gene versions (alleles), 1 from each biological parent, are exceptional. Clinical descriptions of affected families, comprising few carriers only, are scattered throughout the literature, hindering evidence generation.

METHODS

Included in this literature analysis were 5 RET families with ≥1 homozygous carrier and ≥3 heterozygous carriers per family.

RESULTS

In consanguineous families with first-degree cousins, homozygotes presented with node-positive medullary thyroid cancer and pheochromocytoma in their mid-teens, whereas heterozygotes presented in their end-30s and early 40s. Homozygotes developed node-positive medullary thyroid cancer 27.4 years and pheochromocytoma 23 years earlier than heterozygotes. These age differences were smaller in the 15 families carrying founder mutation p.Leu666delinsAsnSer, whereas homozygotes developed node-positive medullary thyroid cancer in their mid-40s, 6 years earlier than heterozygotes in their early 50s.

CONCLUSION

These results, limited in scope and size and modulated by extent of consanguinity, are consistent with moderate dose-response effects accelerating MEN2A development.

Αlpha-thalassemia: A practical overview

α-Thalassemia is an inherited blood disorder characterized by decreased synthesis of α-globin chains that results in an imbalance of α and β globin and thus varying degrees of ineffective erythropoiesis, decreased red blood cell (RBC) survival, chronic hemolytic anemia, and subsequent comorbidities. Clinical presentation varies depending on the genotype, ranging from a silent or mild carrier state to severe, transfusion-dependent or lethal disease. Management of patients with α-thalassemia is primarily supportive, addressing either symptoms (eg, RBC transfusions for anemia), complications of the disease, or its transfusion-dependence (eg, chelation therapy for iron overload). Several novel therapies are also in development, including curative gene manipulation techniques and disease modifying agents that target ineffective erythropoiesis and chronic hemolytic anemia. This review of α-thalassemia and its various manifestations provides practical information for clinicians who practice beyond those regions where it is found with high frequency.

Incidence of Inborn Errors of Metabolism in Newborn Infants: Five Years' Single-Center Experience, Jeddah, Saudi Arabia

Inborn errors of metabolism (IEMs) are inherited biochemical/metabolic disorders that are commonly present in the immediate neonatal period. The aim of this retrospective study was to determine the incidence and distribution of IEMs in newborn infants delivered in our hospital and to evaluate its outcome. A total of 16 494 (99.9%) newborn infants were screened for IEMs. We found 29 newborn infants diagnosed with IEMs, representing an incidence of 1 per ~569 live births and a cumulative incidence of 176 per 100 000 live births of the IEM-positive newborn infants. We detected 11 different types of IEMs, and the top 6 categories were endocrinopathies followed by carbohydrates disorders, vitamin-responsive disorders, organic acid defects, and ketogenesis and ketolysis defects. This study does reflect upon the importance of educating the general population about the perils of Consanguineous Marriages (CMs) in order to reduce related disorders significantly, especially in families who have a history of IEMs.

Exploring the complex spectrum of dominance and recessiveness in genetic cardiomyopathies

Discrete categorization of Mendelian disease genes into dominant and recessive models often oversimplifies their underlying genetic architecture. Cardiomyopathies (CMs) are genetic diseases with complex etiologies for which an increasing number of recessive associations have recently been proposed. Here, we comprehensively analyze all published evidence pertaining to biallelic variation associated with CM phenotypes to identify high-confidence recessive genes and explore the spectrum of monoallelic and biallelic variant effects in established recessive and dominant disease genes. We classify 18 genes with robust recessive association with CMs, largely characterized by dilated phenotypes, early disease onset and severe outcomes. Several of these genes have monoallelic association with disease outcomes and cardiac traits in the UK Biobank, including LMOD2 and ALPK3 with dilated and hypertrophic CM, respectively. Our data provide insights into the complex spectrum of dominance and recessiveness in genetic heart disease and demonstrate how such approaches enable the discovery of unexplored genetic associations.

Consanguinity as a Risk Factor for Autism

PURPOSE

Genetic and environmental risk factors associated with Autism Spectrum Disorders (ASD) continue to be a focus of research worldwide. Consanguinity, the cultural practice of marrying within a family, is common in cultures and societies of the Middle East, North Africa and parts of Asia. Consanguinity has been investigated as a risk factor for ASD in a limited number of studies, with mixed results. We employed registry and survey data from Qatar to evaluate the role of consanguinity as a risk factor for ASD.

METHODS

Data were sourced from a national registry and a population-based survey of autism recently conducted in Qatar. We selected a sample of 891 children (mean age: 8.3 years) with (N = 361) or without (N = 530) ASD. Data on consanguinity and covariates were collected through questionnaires and interviews.

RESULTS

The prevalence of consanguinity in the overall sample was 41.2% with no significant difference between cases and controls (42.1% vs 41.3%; p = .836). In adjusted multiple logistic regression analyses, consanguinity was not associated with risk of ASD (aOR = 1.065; 95% CI: .751-1.509; NS).

CONCLUSION

Parental consanguinity was not associated with autism risk in our study. Replication in other populations with high rates of consanguineous unions is recommended.

Consanguinity and willingness to perform premarital genetic screening in Sudan

Consanguineous marriage is prevalent in certain world regions due to cultural, economic, and social reasons. However, it can lead to negative consequences including an increased risk of genetic disorders in offspring. Premarital genetic screening (PMGS) is an important tool to identify and manage these risks before marriage. This study aimed to assess the magnitude of consanguineous marriage, knowledge of genetic diseases and PMGS, and attitudes and willingness to perform PMGS in Sudan. A national household survey was conducted using a multistage sampling technique, with a sample size of 2272 participants. Data were collected from December 2022 to March 2023 using an interviewer-administered questionnaire. A significant proportion of respondents (364/850, 42.8%) were married to consanguineal partners, with various types of relatedness. Moreover, 32.1% (242/755) of single respondents were planning to marry a close relative, signifying the likely persistence of consanguineous marriages in Sudan. The level of knowledge regarding genetic diseases and PMGS was relatively low in many states of Sudan, indicating the need for increased awareness interventions. A significant number of participants (85.2%) agreed that premarital screening is effective in reducing genetic diseases, whereas 71.2% supported the introduction of a mandatory PMGS program. Excluding married participants, 82.3% (1265/1537) of respondents were willing to perform PMGS, if implemented. These findings reflect the public positive attitude towards introducing the PMGS program and policies in Sudan and underscore the importance of addressing the knowledge gap of PMGS before such a potential implementation.

Genetic Investigation of Consanguineous Pakistani Families Segregating Rare Spinocerebellar Disorders

Spinocerebellar disorders are a vast group of rare neurogenetic conditions, generally characterized by overlapping clinical symptoms including progressive cerebellar ataxia, spastic paraparesis, cognitive deficiencies, skeletal/muscular and ocular abnormalities. The objective of the present study is to identify the underlying genetic causes of the rare spinocerebellar disorders in the Pakistani population. Herein, nine consanguineous families presenting different spinocerebellar phenotypes have been investigated using whole exome sequencing. Sanger sequencing was performed for segregation analysis in all the available individuals of each family. The molecular analysis of these families identified six novel pathogenic/likely pathogenic variants; ZFYVE26: c.1093del, SACS: c.1201C>T, BICD2: c.2156A>T, ALS2: c.2171-3T>G, ALS2: c.3145T>A, and B4GALNT1: c.334_335dup, and three already reported pathogenic variants; FA2H: c.159_176del, APTX: c.689T>G, and SETX: c.5308_5311del. The clinical features of all patients in each family are concurrent with the already reported cases. Hence, the current study expands the mutation spectrum of rare spinocerebellar disorders and implies the usefulness of next-generation sequencing in combination with clinical investigation for better diagnosis of these overlapping phenotypes.

Genetic analysis based on 15 autosomal short tandem repeats (STRs) in the Chaouia population, western center Morocco, and genetic relationships with worldwide populations

The complex demographic history of human populations in North Africa has resulted in a high degree of genetic heterogeneity across the region. However, little is known about the pattern of these genetic variations in its current populations. The present study provides new data on the genetic background of Chaouia, an Arabic-speaking North African population in the western center of Morocco. A random sample of 150 unrelated healthy individuals from Chaouia was assessed using the AmpFLSTR Identifiler kit. The most polymorphic markers were D21S11 and D18S51, with 23 and 22 alleles, respectively. After Bonferroni's correction, two loci (TH01 and D18S51) deviated from Hardy-Weinberg equilibrium. The phylogeny analysis separated North African populations into northeastern and northwestern groups. The Chaouia population was clustered with northwestern Africans. It was the closest to the Berbers of Azrou. The Chaouia shared close genetic affinities with populations from North Africa, the Middle East, and Europe, particularly Iberians, and to a lesser extent with sub-Saharan populations. The pattern of genetic admixture varied across North African populations without a clear correlation between their geographic (northeastern or northwestern) or linguistic identities (Arab or Berber), however, genetic heterogeneity among Berbers was observed. These findings suggest that the diversity observed in North African populations extends geographical and linguistic boundaries. It is further linked to each population's unique and complex demographic history. Human North African population genetics seems to present an intriguing landscape for future studies in the region and its surrounding populations to trace the origins of the genetic heterogeneity observed in these populations.

Glycogen storage disease in two sisters: A case report

Glycogen storage diseases (GSDs) are rare autosomal disorders that result from defects in glycogen metabolism. There are more than 12 types, each with distinct clinical features. Clinical scenario, biochemical abnormalities are useful for suspicion whereas liver biopsy and enzyme assay provides definite diagnosis. We report a case of two sisters with similar clinical symptoms suggestive of the disease.

Analysis of perinatal outcomes of pregnancies from consanguineous marriages in a tertiary hospital in Bursa, Turkey

Aim: In this article, we aimed to contribute to the outcomes of the consanguineous marriage literature by analyzing fetal results in this population. Material and Method: We included 185 patients in this retrospective research. Demographic, clinical, ultrasonographic and delivery data were received from electronic patient records. Also, we recorded the postnatal results, and findings of the infants. By combining all the data, we reported a descriptive analysis of the results of our consanguineous marriage cases with perinatology follow-up. Results: We had 231 pregnant women in the study, and their mean age was 28.9 years. 117 (50.6%) of the pregnant women had first-degree, and 114 (50.4%) had second-degree consanguineous marriages. Fetal findings were evaluated as usual in 157 (68%) of the pregnant in the ultrasonographic scans performed between prenatal 20-24 weeks of gestation. When we look at the first postnatal examinations of the babies, no abnormal findings were in 134 babies (58.8%). Twenty-two infants (9.6%) were followed up in the neonatal intensive care unit with the diagnosis of transient tachypnea of the newborn, and phototherapy was required in 14 infants (6.1%) due to hyperbilirubinemia. The number of cases requiring surgical intervention after delivery or with significant life-threatening anomalies included 56 findings in 32 infants. There were spina bifida cases in 8 infants and hydrocephalus in 9 infants. Conclusion: There was an increased level of congenital anomalies associated with consanguineous marriages. Health care centers should educate individuals regarding the negative role of cousin marriages leading to abnormalities in children.

Live Birth of a Healthy Child in a Couple with Identical mtDNA Carrying a Pathogenic c.471_477delTTTAAAAinsG Variant in the MOCS2 Gene

Molybdenum cofactor deficiency type B (MOCODB; #252160) is an autosomal recessive metabolic disorder that has only been described in 37 affected patients. In this report, we describe the presence of an in-frame homozygous variant (c.471_477delTTTAAAAinsG) in the MOCS2 gene in an affected child, diagnosed with Ohtahara syndrome according to the clinical manifestations. The analysis of the three-dimensional structure of the protein and the amino acid substitutions suggested the pathogenicity of this mutation. To prevent transmitting this mutation to the next generation, we used preimplantation genetic testing for the monogenic disorders (PGT-M) protocol to select MOCS2 gene mutant-free embryos for transfer in an in vitro fertilization (IVF) program. As a result, a healthy child was born. Interestingly, both parents of the proband shared an identical mitochondrial (mt) DNA control region, assuming their close relationship and thus suggesting that both copies of the nuclear rare variant c.471_477delTTTAAAAinsG may have been transmitted from the same female ancestor. Our estimation of the a priori probability of meeting individuals with the same mtDNA haplotype confirms the assumption of a possible distant maternal relationship among the proband’s direct relatives.

Comprehension of premarital screening and genetic disorders among the population of Riyadh

Objective

Premarital, unfortunately, does not cover all possible genetic diseases, such as deafness and congenital heart diseases, diabetes mellitus, and hypertension, nor does it cover unknown genetic mutations that may cause severe defects in subsequent generations. However, the Saudi population has limited knowledge regarding premarital screening tests, which do not detect all genetic disorders or diseases. Hence, we aimed to explore the knowledge and attitudes among the population of Riyadh toward premarital screening.

Methods

A cross-sectional observational study was conducted with a self-administered designed questionnaire. The survey included questions regarding sociodemographic data, genetics, genetic testing, and premarital screening. All data were entered and analyzed in the statistical package SPSS version 22.

Results

A total of 385 participants responded to the questionnaire, and good knowledge among most participants was significantly associated with education level (p < 0.001), sex (p < 0.001), and prior screening (p = 0.001). The overall attitude was positive toward premarital screening, and significant associations of sex and social/marital status with a positive response to premarital screening were observed.

Conclusion

Knowledge and attitudes among the population of Riyadh toward premarital screening must be improved through national awareness programs. In light of our results, a need exists to provide more information and education regarding screening. Further studies must be conducted in urban areas to investigate the level of satisfaction with existing programs.

Genetic Insights from Consanguineous Cardiomyopathy Families

Inherited cardiomyopathies are a prevalent cause of heart failure and sudden cardiac death. Both hypertrophic (HCM) and dilated cardiomyopathy (DCM) are genetically heterogeneous and typically present with an autosomal dominant mode of transmission. Whole exome sequencing and autozygosity mapping was carried out in eight un-related probands from consanguineous Middle Eastern families presenting with HCM/DCM followed by bioinformatic and co-segregation analysis to predict the potential pathogenicity of candidate variants. We identified homozygous missense variants in TNNI3K, DSP, and RBCK1 linked with a dilated phenotype, in NRAP linked with a mixed phenotype of dilated/hypertrophic, and in KLHL24 linked with a mixed phenotype of dilated/hypertrophic and non-compaction features. Co-segregation analysis in family members confirmed autosomal recessive inheritance presenting in early childhood/early adulthood. Our findings add to the mutational spectrum of recessive cardiomyopathies, supporting inclusion of KLHL24, NRAP and RBCK1 as disease-causing genes. We also provide evidence for novel (recessive) modes of inheritance of a well-established gene TNNI3K and expand our knowledge of the clinical heterogeneity of cardiomyopathies. A greater understanding of the genetic causes of recessive cardiomyopathies has major implications for diagnosis and screening, particularly in underrepresented populations, such as those of the Middle East.

Ancient DNA reveals admixture history and endogamy in the prehistoric Aegean

The Neolithic and Bronze Ages were highly transformative periods for the genetic history of Europe but for the Aegean-a region fundamental to Europe's prehistory-the biological dimensions of cultural transitions have been elucidated only to a limited extent so far. We have analysed newly generated genome-wide data from 102 ancient individuals from Crete, the Greek mainland and the Aegean Islands, spanning from the Neolithic to the Iron Age. We found that the early farmers from Crete shared the same ancestry as other contemporaneous Neolithic Aegeans. In contrast, the end of the Neolithic period and the following Early Bronze Age were marked by 'eastern' gene flow, which was predominantly of Anatolian origin in Crete. Confirming previous findings for additional Central/Eastern European ancestry in the Greek mainland by the Middle Bronze Age, we additionally show that such genetic signatures appeared in Crete gradually from the seventeenth to twelfth centuries BC, a period when the influence of the mainland over the island intensified. Biological and cultural connectedness within the Aegean is also supported by the finding of consanguineous endogamy practiced at high frequencies, unprecedented in the global ancient DNA record. Our results highlight the potential of archaeogenomic approaches in the Aegean for unravelling the interplay of genetic admixture, marital and other cultural practices.

Prevalence and risk factors of molar incisor hypomineralization in the Middle East: A systematic review and meta-analysis

Objectives

Molar incisor hypomineralization (MIH) is a growing global concern. Herein, we conducted a systematic review and meta-analysis of the prevalence and associated factors/risk factors of MIH in the Middle East (ME).

Methods

This systematic review and meta-analysis included studies on children with at least one first permanent molar affected by MIH, aged 5-18 years, without syndromes or congenital anomalies, and residing in the ME and included cross-sectional, case-control, and cohort studies. Keywords related to MIH and ME countries were systematically searched until January 10, 2021 in four databases, PubMed, Google Scholar, Science Direct, and the Cochrane Library, following the specified eligibility criteria. The Joanna Briggs Institute quality assessment tool was used to evaluate all included studies. Meta-analyses were conducted to assess the effect of risk factors. The study protocol was registered on the PROSPERO International Prospective Register of Systematic Reviews (Registration No. 247391).

Results

After screening 4,373 documents, 29 eligible studies with a total of 32,636 children aged 7-12 years were included from 11 countries. The frequency of MIH reported in the ME ranged from 2.3% to 40.7%, with a mean prevalence of 15.05%. Pregnancy and early childhood illnesses (odds ratio [OR]: 2.26, 95% confidence interval [CI]: 1.91-2.68; P < 0.001) and factors related to delivery (OR: 2.4, 95% CI: 1.55-3.72; P < 0.001) were statically significantly associated with MIH.

Conclusion

The mean prevalence of MIH in ME aligns with the global MIH prevalence rate. Illnesses and delivery complications are risk factors that could be controlled to prevent MIH. As included studies showed high heterogeneity in the meta-analyses, further evidence from the ME is needed to assess the prevalence and other associated environmental risk factors for MIH.

Multidisciplinary management of Papillon-Lefevre syndrome as a result of consanguineous marriage

Papillon-Lefevre syndrome (PLS) is a rare autosomal recessive syndrome, and consanguinity has been reported in 20%-40% of cases. It is characterised by palmoplantar hyperkeratosis associated with severe early-onset periodontitis and premature loss of primary and permanent teeth. This report describes a case of PLS in a female patient with consanguineously married parents. The patient reported mobile upper front teeth. Clinical examination revealed presence of marked palmoplantar hyperkeratosis.Symmetric, well-demarcated, yellowish, keratotic and confluent plaques were seen on the skin of her palms and soles. Intraoral periodontal examination revealed erythematous gingiva with generalised periodontal pockets. Generalised mobility of teeth was present with clinically missing lower anterior teeth. Based on clinical and radiographic feature and the patient's medical, dental and family history, a diagnosis of PLS was made.

Experience using singleton exome sequencing of probands as an approach to preconception carrier screening in consanguineous couples

BACKGROUND

Consanguineous couples have an increased risk of severe diseases in offspring due to autosomal recessive disorders. Exome sequencing (ES) offers the possibility of extensive preconception carrier screening (PCS) in consanguineous couples who may be at risk of rare genetic disorders.

METHODS

We retrospectively analysed ES data from 65 probands affected with rare genetic disorders born from consanguineous couples. We explored diagnostic yield and carrier status for recessive disorders.

RESULTS

The overall diagnostic yield in a singleton approach was 53.8%, mostly recessive variants. In a hypothetical exome-based PCS, only 11.7% of these causative rare variants would have been missed in the filtering process. Carrier screening for recessive conditions allowed the identification of at least one additional pathogenic or likely pathogenic variant in 85.7% of the probands, being the majority with a gene carrier frequency <1 in 200. In addition, considering only clinically actionable conditions, we estimated that 12.3% of our close consanguineous couples may be at risk for an additional recessive disease.

CONCLUSIONS

Our results demonstrate that ES outperforms panel-based screening in a PCS context in consanguineous couples and could potentially increase their reproductive autonomy and facilitate informed decision-making.

Going Back to Fundamentals: Three Marriageable Actions for Thalassemia and Carrier Population Management

We investigated the impact of three marriageable actions: normal-to-carrier, carrier-to-normal, and carrier-to-carrier marriages on thalassemia and carrier populations. The well-known strategy is limiting the carrier-to-carrier marriage to reduce the thalassemia population. Thus, the other two marriageable actions were often ignored. Other than a simple explanation of their genetic consequences, their important aspect in the thalassemia inheritance mechanism has never been studied at the population level. Moreover, there is no mathematical model investigating problem of interest for blood disorders at the population level. Hence, we developed a mathematical model to examine the possibility of eradication/reduction of thalassemia and carrier populations through each of the three marriageable actions in the long-term. We conducted computer simulations with the demographic data of the United Arab Emirates in which high thalassemia carrier prevalence is identified. We found that promoting more carrier-to-normal marriage will eventually have the same effects on marriage reconsideration for carrier-carrier couples, contributing to the reduction of the carrier population in the long-term. Interestingly, the normal-to-carrier marriage does not necessarily have a similar effect on thalassemia and carrier populations as that of the carrier-to-normal marriage. Thus, the two marriageable actions should be distinguished and also seriously considered in education and public awareness campaigns for thalassemia.

Consanguinity in the Chaouia population (Morocco): prevalence, trends, determinants, fertility, and spontaneous abortions

Background

One of the aspects that helps to understand the genetic structure of a population throughout its biological history is the description of its matrimonial practices. Thus, the objective of this study is to explore consanguinity, one of these practices, to its full extent by identifying the prevalence, determinants, and trends of a consanguineous marriage, as well as its impact on fertility and spontaneous abortions in the Chaouia population, a region located in the western center of Morocco. Therefore, a survey-based cross-sectional study was conducted between January 2019 and January 2020. The sample was collected by province using a stratified random sampling approach, yielding a sample of 788 people. The association between consanguinity and socioeconomic and demographic characteristics, as well as reproductive health and pregnancy outcomes, was described using chi-square and ANOVA analysis. Multivariate logistic regression analysis was used to determine the predictors of a consanguineous marriage.

Results

Our findings revealed a consanguinity rate of 25.38%. The mean inbreeding coefficient was 0.012214. The most common type of union was between first cousins. This practice was strongly associated with an early age at marriage for both genders and with endogamy and immobility of couples, according to their place of birth. Consanguinity was significantly associated with fertility (p < 0.001) and spontaneous abortions (p = 0.029). The average number of pregnancies and spontaneous abortions was higher in consanguineous unions (5.18 ± 0.20/0.47 ± 0.08) compared to non-consanguineous unions (4.33 ± 0.10/0.31 ± 0.03).

Conclusions

Consanguinity is a deeply rooted social and cultural tradition in this population, providing individuals with a sense of social-economic stability while assuring their attachment to the group. Despite being highly associated with fertility, this practice has a significant influence on pregnancy outcomes, namely spontaneous abortions. Therefore, further studies are needed to examine the impact of consanguinity on various aspects of reproductive health and its association with numerous genetic abnormalities and diseases.

Consanguineous Marriage and Early Pregnancy Loss in Rural to Peri-Urban India

Background

Consanguineous marriage (CM) has been linked to spontaneous abortion (SAB), although studies have largely been cross-sectional and likely underestimated early loss. We aimed to determine the relationships between CM and SAB in a prospective pregnancy cohort study in Telangana State, India.

Methods

Data from 661 participants aged 15-35 years in the Longitudinal Indian Family hEalth (LIFE) study actively followed for pregnancy and pregnancy loss were analyzed. SAB was classified as early (< 8) or late (8-22) weeks gestation. We used logistic regression to model the relationships between CM, defined by first-cousin marriage, and SAB, adjusted for maternal age.

Results

Women in CM were at a modestly increased risk of any (OR_adj 1.15, 95% CI 0.69, 1.91) and early (OR_adj 2.03, 95% CI 0.85, 4.83) SAB compared to women in non-CM, although results were not statistically significant. There was no relationship between CM and late SAB.

Conclusion

Among couples in southern India, there was a modest increase in early but not late SAB among CMs which may be explained by the expected influence of chromosomal abnormalities and lethal homozygous recessive disease on early loss. Pre- and Peri-marital Health Counseling that addresses this risk may be warranted.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13224-021-01498-7.

A Multidisciplinary Perspective Addressing the Diagnostic Challenges of Late-Onset Pompe Disease in the Arabian Peninsula Region Developed From an Expert Group Meeting

Pompe disease is a rare, metabolic, autosomal recessive disorder. Early diagnosis is critical for progressive Pompe disease as delays can significantly alter the clinical course of the disease. Diagnostic modalities, including dried blood spot testing and genetic testing, are available and are effective for diagnosing patients with late-onset Pompe disease (LOPD). However, clinicians face numerous clinical challenges related to the diagnosis of the disease. Two expert group committee meetings, involving 11 experts from the United Arab Emirates, Kuwait, the Kingdom of Saudi Arabia, and Oman, were convened in October 2019 and November 2020 respectively to develop a uniform diagnostic algorithm for the diagnosis of pediatric and adult LOPD in the Arabian Peninsula region. During the first meeting, the specialty-specific clinical presentation of LOPD was defined. During the second meeting, a diagnostic algorithm was developed after a thorough validation of clinical presentation or symptoms, which was performed with the aid of existing literature and expert judgement. A consensus was reached on the diagnostic algorithm for field specialists, such as neurologists, rheumatologists, general practitioners/internal medicine specialists, orthopedic specialists, and pulmonologists. This specialty-specific diagnostic referral algorithm for pediatric and adult LOPD will guide clinicians in the differential diagnosis of LOPD.

Outcome of pregnancies with first-trimester increased nuchal translucency and cystic hygroma in a tertiary maternity hospital in United Arab Emirates

OBJECTIVE

To study the outcome of pregnancies with first-trimester increased nuchal translucency and cystic hygromas.

METHODOLOGY

Retrospective study of 132 pregnancies with first-trimester increased nuchal translucency and cystic hygromas, between January 2015 to December 2018 at Corniche Hospital, Abu Dhabi, UAE. Fetal karyotyping, detailed ultrasound at 18-22 weeks and fetal echocardiography were offered to all women. Adverse outcomes included miscarriage, intrauterine fetal death, termination of pregnancy, neonatal death and structural abnormalities.

RESULTS

Of the 132 pregnancies, 13 had NT > 95th percentile, 89 had NT ≥3 mm and 30 had cystic hygroma. Among 13 pregnancies with NT > 95th centile, 7.6% had abnormal karyotype. Among 89 pregnancies with NT ≥3 mm, 29.2% had abnormal karyotype, 13.4% miscarriage, 7.8% underwent TOP, 5.6% intrauterine fetal death, 1.1% neonatal death and 14.6% had structural abnormalities. Among 30 pregnancies with cystic hygroma, 40% had abnormal karyotype, 20% miscarriage, 13.3% TOP, 13.3% intrauterine fetal death, 6.6% had neonatal death and 20% had structural abnormalities.

CONCLUSION

In our study, karyotype abnormalities increased with increasing nuchal translucency with highest risk in fetuses with cystic hygromas. Increased nuchal translucency was associated with adverse pregnancy outcome, which was higher in the group with NT≥6 mm and cystic hygromas.

CLCC1 c. 75C>A Mutation in Pakistani Derived Retinitis Pigmentosa Families Likely Originated With a Single Founder Mutation 2,000-5,000 Years Ago

Background: A CLCC1 c. 75C > A (p.D25E) mutation has been associated with autosomal recessive pigmentosa in patients in and from Pakistan. CLCC1 is ubiquitously expressed, and knockout models of this gene in zebrafish and mice are lethal in the embryonic period, suggesting that possible retinitis pigmentosa mutations in this gene might be limited to those leaving partial activity. In agreement with this hypothesis, the mutation is the only CLCC1 mutation associated with retinitis pigmentosa to date, and all identified patients with this mutation share a common SNP haplotype surrounding the mutation, suggesting a common founder.

Methods: SNPs were genotyped by a combination of WGS and Sanger sequencing. The original founder haplotype, and recombination pathways were delineated by examination to minimize recombination events. Mutation age was estimated by four methods including an explicit solution, an iterative approach, a Bayesian approach and an approach based solely on ancestral segment lengths using high density SNP data.

Results: All members of each of the nine families studied shared a single autozygous SNP haplotype for the CLCC1 region ranging from approximately 1–3.5 Mb in size. The haplotypes shared by the families could be derived from a single putative ancestral haplotype with at most two recombination events. Based on the haplotype and Gamma analysis, the estimated age of the founding mutation varied from 79 to 196 generations, or approximately 2,000–5,000 years, depending on the markers used in the estimate. The DMLE (Bayesian) estimates ranged from 2,160 generations assuming a population growth rate of 0–309 generations assuming a population growth rate of 2% with broad 95% confidence intervals.

Conclusion: These results provide insight into the origin of the CLCC1 mutation in the Pakistan population. This mutation is estimated to have occurred 2000–5,000 years ago and has been transmitted to affected families of Pakistani origin in geographically dispersed locations around the world. This is the only mutation in CLCC1 identified to date, suggesting that the CLCC1 gene is under a high degree of constraint, probably imposed by functional requirements for this gene during embryonic development.

Effectiveness and Adverse Effects of Risperidone in Children with Autism Spectrum Disorder in a Naturalistic Clinical Setting at a University Hospital in Oman

Objective

This study aimed at examining the effectiveness of treating children with autism spectrum disorder (ASD) who present with irritability, aggression, and disruptive behavior at the Sultan Qaboos University Hospital (SQUH) in Muscat, Oman, with risperidone, and to note any sex-based differences among this cohort.

Method

This was a retrospective study conducted at the Department of Behavioral Medicine at SQUH over two years from January 2017 to December 2018. This study included all children aged 3 to 18 years attending the Child and Adolescent Mental Health Service (CAMHS) outpatient clinic with a diagnosis of ASD, based on the DSM-5 criteria, and comorbid disruptive behavior, who had been prescribed risperidone.

Result

This study identified 95 ASD patients (72 males). Male patients' BMI score after 12 months of risperidone treatment showed an increase by 0.62 (1.57 SD; P=0.001); however, there was no significant change among female patients. Somnolence was noted in 69.6% of female patients as compared to 34.7% of males (P=0.003). Among those with a family history of ASD, 5 out of 17 patients had treatment success (29.4%), whereas 70 out of 78 patients (90.0%) who did not have a similar history had successful treatment.

Conclusion

In conclusion, low-dose risperidone monotherapy is effective and well tolerated among some children with ASD who present with disruptive behavior in a naturalistic clinical setting. However, we found that some of the side effects, such as weight gain and somnolence, were concerning.

COVID-19: Impact on linguistic and genetic isolates of India

The rapid expansion of coronavirus SARS-CoV-2 has impacted various ethnic groups all over the world. The burden of infectious diseases including COVID-19 are generally reported to be higher for the Indigenous people. The historical knowledge have also suggested that the indigenous populations suffer more than the general populations in the pandemic. Recently, it has been reported that the indigenous groups of Brazil have been massively affected by COVID-19. Series of studies have shown that many of the indigenous communities reached at the verge of extinction due to this pandemic. Importantly, South Asia also has several indigenous and smaller communities, that are living in isolation. Till date, despite the two consecutive waves in India, there is no report on the impact of COVID-19 for indigenous tribes. Since smaller populations experiencing drift may have greater risk of such pandemic, we have analysed Runs of Homozygosity (ROH) among South Asian populations and identified several populations with longer homozygous segments. The longer runs of homozygosity at certain genomic regions may increases the susceptibility for COVID-19. Thus, we suggest extreme careful management of this pandemic among isolated populations of South Asia.

Congenital Hypotonia: Cracking a SAGA of consanguineous kindred harboring four genetic variants

BACKGROUND

We aimed to determine the molecular and biochemical basis of an extended highly consanguineous family with multiple children presenting severe congenital hypotonia.

METHODS

Clinical investigations, homozygosity mapping, linkage analyses and whole exome sequencing, were performed. mRNA and protein levels were determined. Population screening was followed.

RESULTS

We have identified a novel nonsense variant in NGLY1 in two affected siblings, and compound heterozygosity for three novel RYR1 variants in two affected sisters from another nuclear family within the broad pedigree. Population screening revealed a high prevalence of carriers for both diseases. The genetic variants were proven to be pathogenic, as demonstrated by western blot analyses.

CONCLUSIONS

Revealing the genetic diagnosis enabled us to provide credible genetic counselling and pre-natal diagnosis to the extended family and genetic screening for this high-risk population. Whole exome/genome sequencing should be the first tier tool for accurate determination of the genetic basis of congenital hypotonia. Two different genetic disorders within a large consanguineous pedigree should be always considered.

Molecular Genetic Testing in Pediatric and Adult Neurology in Iraq: New Experience and Challenges from a Developing Country

Inherited neurological disorders are reasonably common in pediatric and adult neurology practices. Genetic testing for such disorders does carry promise, but is fraught with challenges and difficulties. This study was conducted to assess the utility of genetic testing in a cohort of 200 patients who had neurological disorders, suspected to be of inherited origin, and for whom molecular genetic testing was requested during the period 2014 to 2019. Two hundred and eight tests were ordered. The characteristics of that practice were reviewed. Further, we summarized the challenges and highlighted the concerns that were raised. The medical records of 200 patients were retrieved and reviewed to assess the demographic characteristics of the cohort, their clinical presentation, genetic test requested for each, and the interpretation of the test results.

A Protocol for Preconceptional Screening of Consanguineous Couples Using Whole Exome Sequencing

Genetic studies performed in consanguineous couples suggest that the reproductive risk that distinguish them from other couples in the general population is related to autosomal recessive (AR) diseases. This risk is scattered among the thousands of known and potential AR diseases. Thus, for effective preconceptional screening of consanguineous couples it is necessary a test that encompasses the largest number of genes possible. For that reason, we decided to create a protocol based on whole exome sequencing (WES). We sequenced completely the exomes of 39 consanguineous couples at high coverage (∼100×). Applying bioinformatics filters, we could detect genetic variants that were simultaneously present in both members of the couple in all genes listed in the Clinical Genomics Database as causally related to AR diseases. Shared variants were then assessed for pathogenicity. For non-truncating variants (missense and in-frame indels) we considered as pathogenic or likely pathogenic only the variants included as such in the ClinVar database. Shared truncating variants (frameshift, non-sense, and canonical splice variants) were considered likely pathogenic when loss-of-function was a known mechanism of disease. The 39 consanguineous cases included two couples with a coefficient of genetic relationship (CGR) of 0.25, 26 couples with a CGR of 0.125, three couples with a CGR of 0.0625 and eight couples with a CGR of 0.03125. In 21 of the 39 couples (53.8%) we ascertained sharing of heterozygosity for at least one variant considered pathogenic or likely pathogenic for an AR disease. In eight couples we found sharing of heterozygosity for at least two pathogenic variants. Once the specific pathogenic variant was identified, it became possible for the couple to undergo prenatal diagnosis or, if desired, preimplantation genetic diagnosis (PGD) involving in vitro fertilization and embryo screening. In conclusion, our results demonstrate that preconceptional screening by WES is a useful new procedure that should be incorporated in the genetic counseling of all consanguineous couples.

Impact of Parental Consanguinity on the Frequency of Orofacial Clefts in Jordan

ABSTRACT

Orofacial clefts (OFCs) are the most common craniofacial congenital anomalies, and its prevalence is highest among Asian populations. The aim of this retrospective case-control study is to evaluate the effect of parental consanguinity on the frequency of OFCs at Jordan University Hospital over a 15-year-period. The study group consists of all patients with OFCs presented to the major tertiary referral center in Jordan during the last 15 years, along with age and gender-matched controls. The authors analyzed the risk of different predictors, including consanguinity, on the development of OFCs, both cleft lip with or without cleft palate (CL/P) and cleft palate only. A total of 332 participants were included in this study, with a mean age of 74.36 (±48.75) months. The authors included 129 (38.9%) OFCs, and 203 (61.1%) controls. The percentage of parental consanguinity among OFCs group was 41.1%, compared to only 24.1% for controls, a difference that was statistically significant (P = 0.001). On logistic regression analysis, the authors found that parental consanguinity is a significant predictor for the occurrence of OFCs (P = 0.007), where people with consanguineous marriage have 2 times higher risk (odds ratio of 0.504, with 95% confidence interval 0.306-0.830) to have offspring with OFCs. Moreover, lower birth weight babies are also significantly more associated with OFCs (P = 0.014), with an odds ratio of 1.819 (95% confidence interval 1.131 2.926). Among the Jordanian population, the authors found that consanguinity and lower birth weight were the only variables significantly associated with the development of OFCs.

Exome-based preconception carrier testing for consanguineous couples in China

OBJECTIVE

To evaluate the utility of clinical exome sequencing (ES)-based carrier screening in Chinese consanguineous couples.

METHODS

Consanguineous couples were screened for autosomal recessive (AR) disorders using the clinical ES of 5000 genes associated with human diseases.

RESULTS

We recruited 14 couples who elected to have sequencing. One couple was related as first cousins and 13 as second cousins. Both partners carrying the same pathogenic variant were detected in four couples. One couple was found in which one partner carried a splice variant, and the other had a missence variant of the same gene. These five couples were identified as being at risk of having a child affected by an AR disorder.

CONCLUSION

Our study demonstrates that ES-based preconception screening yields a clinical value for Chinese consanguineous couples. It enables to detect at-risk couples for rare AR diseases.

Oral Phenotype and Salivary Microbiome of Individuals With Papillon-Lefèvre Syndrome

Papillon-Lefèvre syndrome (PLS) is an autosomal recessive rare disease, main characteristics of which include palmoplantar hyperkeratosis and premature edentulism due to advanced periodontitis (formerly aggressive periodontitis). This study aimed to characterize the oral phenotype, including salivary parameters, and the salivary microbiome of three PLS sisters, comparatively. Two sisters were toothless (PLSTL1 and PLSTL2), and one sister had most of the teeth in the oral cavity (PLST). Total DNA was extracted from the unstimulated saliva, and the amplicon sequencing of the 16S rRNA gene fragment was performed in an Ion PGM platform. The amplicon sequence variants (ASVs) were obtained using the DADA2 pipeline, and the taxonomy was assigned using the SILVA v.138. The main phenotypic characteristics of PLS were bone loss and premature loss of primary and permanent dentition. The PLST sister presented advanced periodontitis with gingival bleeding and suppuration, corresponding to the advanced periodontitis as a manifestation of systemic disease, stage IV, grade C. All three PLS sisters presented hyposalivation as a possible secondary outcome of the syndrome. Interestingly, PLST salivary microbiota was dominated by the uncultured bacteria Bacterioidales (F0058), Fusobacterium, Treponema, and Sulfophobococcus (Archaea domain). Streptococcus, Haemophilus, and Caldivirga (Archaea) dominated the microbiome of the PLSTL1 sister, while the PLSTL2 had higher abundances of Lactobacillus and Porphyromonas. This study was the first to show a high abundance of organisms belonging to the Archaea domain comprising a core microbiome in human saliva. In conclusion, a PLST individual does have a microbiota different from that of the periodontitis' aggressiveness previously recognized. Due to an ineffective cathepsin C, the impairment of neutrophils probably provided a favorable environment for the PLS microbiome. The interactions of Bacteroidales F0058, Caldivirga, and Sulfophobococcus with the microbial consortium of PLS deserves future investigation. Traditional periodontal therapy is not efficient in PLS patients. Unraveling the PLS microbiome is essential in searching for appropriate treatment and avoiding early tooth loss.

A novel frameshift pathogenic variant in ST3GAL5 causing salt and pepper developmental regression syndrome (SPDRS): A case report

GM3 synthase deficiency is associated with salt and pepper developmental regression syndrome (SPDRS), a rare genetic disorder. Herein, we report the first Iranian patient with SPDRS. We detected a novel pathogenic variant of ST3GAL5 (NM_003896.4: c.1030_1031del, p.Ile344Cysfs*11). The proband had intellectual disability (ID), failure to thrive, cerebral atrophy, microcephaly, and atonic seizures. The main future challenge proceeding from the results of this study is the prenatal detection of the newly discovered variant; the next step would involve further studies to elucidate the phenotypic spectrum of SPDRS and detect new variants that could cause symptoms ranging from mild to severe.

Biallelic variants in PSMB1 encoding the proteasome subunit β6 cause impairment of proteasome function, microcephaly, intellectual disability, developmental delay and short stature

The molecular cause of the majority of rare autosomal recessive disorders remains unknown. Consanguinity due to extensive homozygosity unravels many recessive phenotypes and facilitates the detection of novel gene-disease links. Here, we report two siblings with phenotypic signs, including intellectual disability (ID), developmental delay and microcephaly from a Pakistani consanguineous family in which we have identified homozygosity for p(Tyr103His) in the PSMB1 gene (Genbank NM_002793) that segregated with the disease phenotype. PSMB1 encodes a β-type proteasome subunit (i.e. β6). Modeling of the p(Tyr103His) variant indicates that this variant weakens the interactions between PSMB1/β6 and PSMA5/α5 proteasome subunits and thus destabilizes the 20S proteasome complex. Biochemical experiments in human SHSY5Y cells revealed that the p(Tyr103His) variant affects both the processing of PSMB1/β6 and its incorporation into proteasome, thus impairing proteasome activity. CRISPR/Cas9 mutagenesis or morpholino knock-down of the single psmb1 zebrafish orthologue resulted in microcephaly, microphthalmia and reduced brain size. Genetic evidence in the family and functional experiments in human cells and zebrafish indicates that PSMB1/β6 pathogenic variants are the cause of a recessive disease with ID, microcephaly and developmental delay due to abnormal proteasome assembly.

Genetic counseling and screening of consanguineous couples and their offspring practice resource: Focused Revision

There are no evidence-based guidelines to inform genetic counseling for consanguineous couples and their offspring. This focused revision builds on the expert opinions from the original publication of "Genetic Counseling and Screening of Consanguineous Couples and Their Offspring," based on a review of literature published since 2002.

Frequency and management of medically actionable incidental findings from genome and exome sequencing data; A systematic review

The application of whole genome/exome sequencing technologies in clinical genetics and research has resulted in the discovery of incidental findings unrelated to the primary purpose of genetic testing. The American College of Medical Genetics and Genomics published guidelines for reporting pathogenic and likely pathogenic variants that are deemed to be medically actionable, which allowed us to learn about the epidemiology of incidental findings in different populations. However, consensus guidelines for variant reporting and classification are still lacking. We conducted a systematic literature review of incidental findings in whole genome/exome sequencing studies to obtain a comprehensive understanding of variable reporting and classification methods for variants that are deemed to be medically actionable across different populations. The review highlights the elements that demand further consideration or adjustment.

Biallelic variants in TMEM222 cause a new autosomal recessive neurodevelopmental disorder

PURPOSE

To elucidate the novel molecular cause in families with a new autosomal recessive neurodevelopmental disorder.

METHODS

A combination of exome sequencing and gene matching tools was used to identify pathogenic variants in 17 individuals. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) and subcellular localization studies were used to characterize gene expression profile and localization.

RESULTS

Biallelic variants in the TMEM222 gene were identified in 17 individuals from nine unrelated families, presenting with intellectual disability and variable other features, such as aggressive behavior, shy character, body tremors, decreased muscle mass in the lower extremities, and mild hypotonia. We found relatively high TMEM222 expression levels in the human brain, especially in the parietal and occipital cortex. Additionally, subcellular localization analysis in human neurons derived from induced pluripotent stem cells (iPSCs) revealed that TMEM222 localizes to early endosomes in the synapses of mature iPSC-derived neurons.

CONCLUSION

Our findings support a role for TMEM222 in brain development and function and adds variants in the gene TMEM222 as a novel underlying cause of an autosomal recessive neurodevelopmental disorder.

Factors leading to neonatal mortality due to neonatal purpura fulminans through the lens of a child death review

A case of neonatal death due to neonatal purpura fulminans (NPF) was brought to community physicians' notice by the auxiliary nurse midwife in her catchment area as part of the routine demographic health surveillance. The community physician then conducted the child death review in the community. The neonate was born out of consanguineous marriage (mother married to her first-degree maternal cousin) with spontaneous conception. This neonate was fourth in the birth order. The second-order and third-order births had also suffered from NPF and died. The baby was delivered in a tertiary care setting, and the paediatric surgeon planned debridement of the affected part on the third day of the birth, as per the mother. However, due to inadequate counselling regarding the procedure, mother left the hospital without seeking care against medical advice, and the child died at home.

History of the methodology of disease gene identification

The past 45 years have witnessed a triumph in the discovery of genes and genetic variation that cause Mendelian disorders due to high impact variants. Important discoveries and organized projects have provided the necessary tools and infrastructure for the identification of gene defects leading to thousands of monogenic phenotypes. This endeavor can be divided in three phases in which different laboratory strategies were employed for the discovery of disease-related genes: (i) the biochemical phase, (ii) the genetic linkage followed by positional cloning phase, and (iii) the sequence identification phase. However, much more work is needed to identify all the high impact genomic variation that substantially contributes to the phenotypic variation.

Association of Parental Consanguinity With Papillary Thyroid Carcinoma: A Case-Control Study

CONTEXT

Papillary thyroid carcinoma (PTC) is the most common type of nonmedullary thyroid carcinoma. Uncommonly, PTC is associated with multiple genetic alterations and chromosomal abnormalities and displays familial patterns of inheritance. Parental consanguinity increases susceptibility to many genetic disorders.

OBJECTIVE

This work aimed to investigate the association of parental consanguinity with PTC.

METHODS

This case-control study of PTC patients compared with healthy controls took place in a tertiary referral hospital. We recruited 200 PTC patients who were managed at the endocrinology outpatient clinics of the Jordan University Hospital, and we recruited 515 healthy controls from a nonclinical setting. We interviewed all participants and collected sociodemographic data. We reviewed the family pedigrees of each participant four generations back and excluded any participant who was related. We established whether the parents of each participant were first cousins, first cousins once removed, second cousins, or unrelated. We then used binary logistic regression to assess the association of parental consanguinity with PTC adjusted for age, sex, smoking status, body mass index, and parental education.

RESULTS

We recruited 715 participants. The numbers of PTC patients and healthy controls were 200 (28.0%) and 515 (72.0%), respectively. The rate of parental consanguinity was 25.5% in PTC patients and 12.2% in healthy controls. Parental consanguinity was significantly associated with PTC (adjusted odds ratio, 2.60; 95% CI, 1.63-4.17; P < .001).

CONCLUSION

Parental consanguinity is a risk factor for PTC. Our findings should be considered during familial risk assessment and genetic counseling, especially in populations with high rates of consanguinity.

Consanguinity-based analysis of exome sequencing yields likely genetic causes in patients with inherited retinal dystrophy

Background

Consanguineous families have a relatively high prevalence of genetic disorders caused by bi-allelic mutations in recessive genes. This study aims to evaluate the effectiveness and efficiency of a consanguinity-based exome sequencing approach to capturing genetic mutations in inherited retinal dystrophy families with consanguineous marriages.

Methods

Ten unrelated consanguineous families with a proband affected by inherited retinal dystrophy were recruited in this study. All participants underwent comprehensive ophthalmic examinations. Whole exome sequencing was performed, followed by a homozygote-prior strategy to rapidly filter disease-causing mutations. Bioinformatic prediction of pathogenicity, Sanger sequencing and co-segregation analysis were carried out for further validation.

Results

In ten consanguineous families, a total of 10 homozygous mutations in 8 IRD genes were identified, including 2 novel mutations, c.1654_1655delAG (p. R552Afs*5) in gene FAM161A in a patient diagnosed with retinitis pigmentosa, and c.830T > C (p.L277P) in gene CEP78 in a patient diagnosed with cone and rod dystrophy.

Conclusion

The genetic etiology in consanguineous families with IRD were successfully identified using consanguinity-based analysis of exome sequencing data, suggesting that this approach could provide complementary insights into genetic diagnoses in consanguineous families with variant genetic disorders.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01902-5.

Taurine treatment of retinal degeneration and cardiomyopathy in a consanguineous family with SLC6A6 taurine transporter deficiency

In a consanguineous Pakistani family with two affected individuals, a homozygous variant Gly399Val in the eighth transmembrane domain of the taurine transporter SLC6A6 was identified resulting in a hypomorph transporting capacity of ~15% compared with normal. Three-dimensional modeling of this variant has indicated that it likely causes displacement of the Tyr138 (TM3) side chain, important for transport of taurine. The affected individuals presented with rapidly progressive childhood retinal degeneration, cardiomyopathy and almost undetectable plasma taurine levels. Oral taurine supplementation of 100 mg/kg/day resulted in maintenance of normal blood taurine levels. Following approval by the ethics committee, a long-term supplementation treatment was introduced. Remarkably, after 24-months, the cardiomyopathy was corrected in both affected siblings, and in the 6-years-old, the retinal degeneration was arrested, and the vision was clinically improved. Similar therapeutic approaches could be employed in Mendelian phenotypes caused by the dysfunction of the hundreds of other molecular transporters.

Birth prevalence of phenylalanine hydroxylase deficiency: a systematic literature review and meta-analysis

BACKGROUND

Phenylalanine hydroxylase (PAH) deficiency is an autosomal recessive disorder that results in elevated concentrations of phenylalanine (Phe) in the blood. If left untreated, the accumulation of Phe can result in profound neurocognitive disability. The objective of this systematic literature review and meta-analysis was to estimate the global birth prevalence of PAH deficiency from newborn screening studies and to estimate regional differences, overall and for various clinically relevant Phe cutoff values used in confirmatory testing.

METHODS

The protocol for this literature review was registered with PROSPERO (International prospective register of systematic reviews). Pubmed and Embase database searches were used to identify studies that reported the birth prevalence of PAH deficiency. Only studies including numeric birth prevalence reports of confirmed PAH deficiency were included.

RESULTS

From the 85 publications included in the review, 238 birth prevalence estimates were extracted. After excluding prevalence estimates that did not meet quality assessment criteria or because of temporal and regional overlap, estimates from 45 publications were included in the meta-analysis. The global birth prevalence of PAH deficiency, estimated by weighting regional birth prevalences relative to their share of the population of all regions included in the study, was 0.64 (95% confidence interval [CI] 0.53-0.75) per 10,000 births and ranged from 0.03 (95% CI 0.02-0.05) per 10,000 births in Southeast Asia to 1.18 (95% CI 0.64-1.87) per 10,000 births in the Middle East/North Africa. Regionally weighted global birth prevalences per 10,000 births by confirmatory test Phe cutoff values were 0.96 (95% CI 0.50-1.42) for the Phe cutoff value of 360 ± 100 µmol/L; 0.50 (95% CI 0.37-0.64) for the Phe cutoff value of 600 ± 100 µmol/L; and 0.30 (95% CI 0.20-0.40) for the Phe cutoff value of 1200 ± 200 µmol/L.

CONCLUSIONS

Substantial regional variation in the birth prevalence of PAH deficiency was observed in this systematic literature review and meta-analysis of published evidence from newborn screening. The precision of the prevalence estimates is limited by relatively small sample sizes, despite widespread and longstanding newborn screening in much of the world.