Data from: Deciphering the fine-structure of tribal admixture in the Bedouin population using genomic data

The Bedouin Israeli population is highly inbred and structured with a very high prevalence of recessive diseases. Many studies in the past two decades focused on linkage analysis in large, multiple consanguineous pedigrees of this population. The advent of high-throughput technologies motivated researchers to search for rare variants shared between smaller pedigrees, integrating data from clinically similar yet seemingly non-related sporadic cases. However, such analyses are challenging because, without pedigree data, there is no prior knowledge regarding possible relatedness between the sporadic cases. Here, we describe models and techniques for the study of relationships between pedigrees and use them for the inference of tribal co-ancestry, delineating the complex social interactions between different tribes in the Negev Bedouins of southern Israel. Through our analysis, we differentiate between tribes that share many yet small genomic segments because of co-ancestry versus tribes that share larger segments because of recent admixture. The emergent pattern is well correlated with the prevalence of rare mutations in the different tribes. Tribes that do not intermarry, mostly because of social restrictions, hold private mutations, whereas tribes that do intermarry demonstrate a genetic flow of mutations between them. Thus, social structure within an inbred community can be delineated through genomic data, with implications to genetic counseling and genetic mapping.

以色列贝都因人群体高度近亲繁育且群体结构清晰，隐性疾病患病率居高不下。过去二十年间，诸多研究均聚焦于该群体中大型多血缘近亲家系的连锁分析。随着高通量技术的问世，研究者们转而探索小型家系间共有的罕见变异，并整合了临床表型相似但看似无亲缘关系的散发病例数据。然而此类分析颇具挑战：由于缺乏家系数据，无法预先获知散发病例间可能存在的亲缘关系。本研究详述了用于家系间亲缘关系分析的模型与技术，并将其应用于部落共祖关系的推断，以此刻画以色列南部内盖夫地区贝都因人不同部落间复杂的社会互动模式。通过本次分析，我们区分了两类部落：一类因远古共祖而共享大量短小基因组片段，另一类则因近期族群融合而共享更长的基因组片段。该结果呈现的模式与不同部落中罕见突变的患病率高度相关。大多因社会限制而避免异族通婚的部落拥有专属突变；而存在跨部落通婚行为的部落则呈现出突变在部落间的遗传流动。由此可见，可通过基因组数据刻画近亲繁育社群的社会结构，该发现对遗传咨询与基因定位研究均具有重要应用价值。