BACKGROUND: The high prevalence of endogamy, or inbreeding, in northeastern Brazil, is due to historical and cultural factors, with large families living in cities far from the coast and subject to low socioeconomic and infrastructure levels. This breeding practice results in low genetic variability with an increased prevalence of rare autosomal recessive and neurodegenerative diseases, such as spinal muscular atrophy (SMA).
OBJECTIVE: Understanding the impact of communicating the diagnosis of SMA on the mental health of patients and their families and the differences between the Northeast (endogamous region) and the other regions of Brazil (non-endogamous ones).
METHODS: Cross-sectional study obtained through a structured questionnaire about the moment of receiving the SMA diagnosis, containing the Impact of Event Scale-Revised.
CONCLUSIONS: The sample consisted of 100 volunteers from all regions of Brazil, 47 patients diagnosed with SMA and 53 family members present at the time of the diagnosis. There was a predominance of females (83%) and homogeneity between the groups for the variables gender, age, color, education, religion, and SMA subtype (1, 2, 3, and 4). The Northeast region, representing 43% of the sample, despite being less economically favored, showed greater satisfaction with medical care and inclusion in health services, with less self-reported psychological trauma and fewer signs of post-traumatic stress disorder (PTSD) related to the moment of receiving the diagnosis. The non-endogamous regions, in turn, reported the presence of strong waves of emotion, sleep problems, feelings of irritability, anger, and the presence of bad thoughts related to this situation.
CONCLUSIONS: The feeling of inclusion in health services and satisfaction with medical care in the endogamous region had a positive impact on the mental health of those involved, reducing psychological trauma and signs of PTSD arising from the communication of the SMA diagnosis.

People tend to select romantic partners who belong to the same social group as themselves (i.e., endogamy). However, there is limited research on the proximal psychological motivations for choosing endogamous relationship partners. The purpose of this research was to develop a measure of motivations for endogamous relationship preferences and to assess whether such motivations were associated with actual dating experiences and attitudes toward endogamy across four common social categories: race and/or ethnicity, religion, social class, and education. Data from an online sample of participants (Study 1, n = 341) were used to generate items assessing motivations for endogamous relationship preferences. This initial set of items was administered to a new sample of participants (Study 2, n = 193) to establish the component structure of the measure and to examine whether the motivational components were associated with participants\' past exogamous dating experiences as well as the perceived importance of dating within one\'s own racial and/or ethnic, religious, socioeconomic, and educational group. Endogamy motivations characterized by intergroup prejudice were the strongest and most consistent correlates of endogamous relationships and the perceived importance of endogamy. Study 3 (n = 332) replicated the component structure of the measure and the general pattern of associations documented in Study 2, and provided evidence for the measure\'s construct validity. The overall findings suggest that intergroup prejudice partially explains preferences for endogamous relationships.

The genetic disease spectrum in Tunisia arises from the founder effect, genetic drift, selection, and consanguinity. The latter represents a deviation from panmixia, characterized by a non-random matrimonial choice that may be subject to several rules, such as socio-cultural, economic, or other factors. This shifts the genetic structure away from the Hardy-Weinberg equilibrium, increasing homozygous genotypes and decreasing heterozygotes, thus raising the frequency of autosomal recessive diseases. Similar to other Arab populations, Tunisia displays high consanguinity rates that vary geographically. Approximately 60% of reported diseases in Tunisia are autosomal recessive, with consanguinity possibly occurring in 80% of families for a specific disease. In inbred populations, consanguinity amplifies autosomal recessive disease risk, yet it does not influence autosomal dominant disease likelihood but rather impacts its phenotype. Consanguinity is also suggested to be a major factor in the homozygosity of deleterious variants leading to comorbid expression. At the genome level, inbred individuals inherit homozygous mutations and adjacent genomic regions known as runs of homozygosity (ROHs). Short ROHs indicate distant inbreeding, while long ROHs refer to recent inbreeding. ROHs are distributed rather irregularly across the genome, with certain short regions featuring an excess of ROH, known as ROH islands. In this review, we discuss consanguinity\'s impact on population health and genome dynamics, using Tunisia as a model.

Despite increasing diversity within many societies, ethnically endogamous unions remain common. In contexts where one ethnic minority has lived alongside the majority for centuries, understanding who partners with whom is central to understanding how ethnic boundaries are maintained or dissolved. This study examines the role of own and parental ethnolinguistic affiliation for the first partner choice in Finland. We provide a unique test of the relevance of ethnic endogamy across two generations, in a context where both groups are native, but one (Finnish speakers) overwhelmingly outnumbers the other (Swedish speakers). Using register data on the total population, we examine how a person\'s ethnolinguistic affiliation and background affect the choice of the first cohabiting partner in terms of the partner\'s ethnolinguistic affiliation and background. We apply discrete-time competing risk models for men and women born 1970-1983. Results indicate that Swedish-registered individuals with two Swedish-registered parents are, by far, the most likely to partner with another Swedish-registered person with endogamous background. Partnering with a Swedish-registered person with exogamous background is most likely among individuals who themselves come from mixed unions. Patterns are remarkably consistent across gender, and adjustments for education and residential area only marginally alter the results.

Introduction  Cancer is a multifactorial disease dependent on the influence of genetic and environmental factors. About 10% of cancers are associated with germline mutations, which predispose to a higher risk of developing cancer. Currently, the use of panels that identify susceptibility and/or association genes cancer has been increasingly used, both in clinical practice and in scientific research. Objective  To investigate genetic mutations in patients with a profile for hereditary cancer in individuals from a region of northeast Brazil, where there is a high frequency of endogenous and consanguineous marriages. Methods  A set of 17 genes ( BRCA1 , BRCA2 , APC , TP53 , PTEN , RET , VHL , RB1 , CDKN2 , CDH1 , CHEK2 , MLH1 , MSH2 , MSH6 , MUTYH , XPA , and XPC ) associated with cancer and hereditary syndromes were analyzed. Fifteen patients with a hereditary cancer profile were evaluated. Results  The pathogenic variant found was c.1187G > A (p.Gly396Asp), rs36053993 in the MUTYH gene in a male patient diagnosed with melanoma at the age of 43 years and a family history for this tumor. This gene encodes an important enzyme related to DNA repair and has been associated with other types of cancer, this is the first report of an association with melanoma, the biological plausibility of this association is given once the MUTYH protein is expressed in the skin tissue and is responsible for repairing damage caused, for example, by sun exposure. Conclusion  The results of this study suggest that this mutation may be important for the hereditary predisposition to melanoma, but a broader investigation of this mutation is needed.

Recessive alleles have been shown to directly affect both human Mendelian disease phenotypes and complex traits. Pedigree studies also suggest that consanguinity results in increased childhood mortality and adverse health phenotypes, presumably through penetrance of recessive mutations. Here, we test whether the accumulation of homozygous, recessive alleles decreases reproductive success in a human population. We address this question among the Namibian Himba, an endogamous agro-pastoralist population, who until very recently practiced natural fertility. Using a sample of 681 individuals, we show that Himba exhibit elevated levels of \"inbreeding,\" calculated as the fraction of the genome in runs of homozygosity (FROH). Many individuals contain multiple long segments of ROH in their genomes, indicating that their parents had high kinship coefficients. However, we do not find evidence that this is explained by first-cousin consanguinity, despite a reported social preference for cross-cousin marriages. Rather, we show that elevated haplotype sharing in the Himba is due to a bottleneck, likely in the past 60 generations. We test whether increased recessive mutation load results in observed fitness consequences by assessing the effect of FROH on completed fertility in a cohort of postreproductive women (n = 69). We find that higher FROH is significantly associated with lower fertility. Our data suggest a multilocus genetic effect on fitness driven by the expression of deleterious recessive alleles, especially those in long ROH. However, these effects are not the result of consanguinity but rather elevated background identity by descent.

BACKGROUND: Dysferlinopathy has a high prevalence in relatively isolated ethnic groups where consanguineous marriages are characteristic and/or the founder effect exists. However, the frequency of endemic mutations in most isolates has not been investigated.
METHODS: The prevalence of the pathological DYSF gene variant (NM_003494.4); c.200_201delinsAT, p. Val67Asp (rs121908957) was investigated in an isolated Avar population in the Republic of Dagestan. Genetic screenings were conducted in a remote mountainous region characterized by a high level of consanguinity among its inhabitants. In total, 746 individuals were included in the screenings.
RESULTS: This pathological DYSF gene variant causes two primary phenotypes of dysferlinopathy: limb-girdle muscular dystrophy (LGMD) type R2 and Miyoshi muscular dystrophy type 1. Results indicated a high prevalence of the allele at 14% (95% confidence interval [CI]: 12-17; 138 out of 1518 alleles), while the allele in the homozygous state was detected in 29 cases-3.8% (CI: 2.6-5.4). The population load for dysferlinopathy was 832.3 ± 153.9 per 100,000 with an average prevalence of limb-girdle muscular dystrophies ranging from 0.38 ± 0.38 to 5.93 ± 1.44 per 100,000.
CONCLUSIONS: A significant burden of the allele was due to inbreeding, as evidenced by a deficiency of heterozygotes and the Wright fixation index equal to 0.14 (CI 0.06-0.23).

We use data on research collaboration among 5,230 scholars in the University of São Paulo between 2000 and 2019 to understand how a network with high academic endogamy is structured, to identify if academic collaboration is more commonly found among those who share endogamy status, and to analyze if the likelihood of tie formation is distinct among inbred and non-inbred scholars. Results show growth of collaborations over time. However, ties between scholars are more likely to occur when endogamy status is shared by both inbred and non-inbred ones. Furthermore, such homophily effect seems to gradually be more influential on non-inbred scholars, suggesting this institution could be missing out on opportunities of exploring non-redundant information from within its own faculty members.

Hemoglobinopathy is a major concern among the tribal population which constitutes 8.6% of the total population, and West Bengal (WB) is the home to 5.3 million tribes. The present study was conducted on 52,880 tribal school students from all the districts of WB. Written informed consent and peripheral blood were collected for complete blood count and high-performance liquid chromatography analysis. Beta trait was 5.3%, sickle trait was 2.35%, and hemoglobin (Hb) E (HbE) trait was 1.4% in this population. About 37.8% of beta trait belonged to the Santal tribe and 21.5% belonged to Oraon. HbS is mainly found in Alipurduar and Jalpaiguri districts at the prevalence of 3.69% and 5.96%, respectively. HbE trait is found at 6.06% in Alipurduar, of which 51% of cases are from Mech tribe only found in this district. Unlike central and Western parts of India, HbS trait in WB was significantly low among the tribes. A high prevalence of consanguinity among the tribes is considered responsible for the high rate of hemoglobinopathy.

Thalassemia is a major health challenge in the United Arab Emirates (UAE), however previous studies have focused on genetics and molecular characterisation while neglecting culture and society. In this commentary, we discuss how tradition and religion in the UAE (e.g. consanguinity, endogamy, illegality of abortion and in vitro fertilisation, adoption restrictions), and limited academic research, affect the prevention and management of the blood disorder. It is suggested that changing attitudes towards traditional marriage practices, education and awareness campaigns targeting families and young people, and earlier genetic testing, are culturally acceptable solutions to curbing the high incidence of thalassemia in the UAE.