Inbreeding levels in Northeast Brazil: strategies for the prospecting of new genetic disorders

Abstract

A new autosomal recessive genetic condition, the SPOAN syndrome (an acronym for spastic paraplegia, optic atrophy and neuropathy syndrome), was recently discovered in an isolated region of the State of Rio Grande do Norte in Northeast Brazil, in a population that was identified by the IBGE (Brazilian Institute of Geography and Statistics) as belonging to the Brazilian communities with the highest rates of “deficiencies” (Neri, 2003), a term used to describe diseases, malformations, and handicaps in general. This prompted us to conduct a study of consanguinity levels in five of its municipal districts by directly interviewing their inhabitants. Information on 7,639 couples (corresponding to about 40% of the whole population of the studied districts) was obtained. The research disclosed the existence of very high frequencies of consanguineous marriages, which varied from about 9% to 32%, suggesting the presence of a direct association between genetic diseases such as the SPOAN syndrome, genetic drift and inbreeding levels. This fact calls for the introduction of educational programs for the local populations, as well as for further studies aiming to identify and characterize other genetic conditions. Epidemiological strategies developed to collect inbreeding data, with the collaboration of health systems available in the region, might be very successful in the prospecting of genetic disorders.

Estimated birth prevalence of mucopolysaccharidoses in Brazil

“…Most patients with a history of consanguinity were from the Southeast and Northeast regions. In the latter, previous studies have reported high rates of consanguinity in specific areas of such states as Bahia (Costa‐Motta et al, ), Paraíba (Weller et al, ) e Rio Grande do Norte (Santos et al, ). According to a March of Dimes report, an estimated 1 to 10% of unions in South America are consanguineous (Christianson, Howson, & Modell, ), a rate far below that found in the present study and in the aforementioned investigations.…”

Consanguinity and Geographic Origin of Patients With Autosomal Recessive Metabolic Disorders Evaluated in a Reference Service in Campinas, Brazil

“…3 In Brazil, changes in sociodemographic characteristics shrank the rates of consanguineous marriages from 4.8% 4 to 1.87% 3 in less than a half-century, but consanguinity remains high in some regions. In the northeast states, studies reported frequencies from 9% to 32% in Rio Grande do Norte 5 and from 6% to 41% in Paraíba. 6 Brazil has continental size in geographic dimension and population presenting with multiple ethnical backgrounds, although the majority is composed by bi-and trihybrids from Caucasians, African descendants, and Native Indians.…”

A Community-Based Study of Mucopolysaccharidosis Type VI in Brazil: The Influence of Founder Effect, Endogamy and Consanguinity

“…As in other states of Northeast Brazil, e.g. Rio Grande do Norte and Paraíba [18,19] , there is a strong tradition of community endogamy and consanguineous marriage, in part due to geographical and social isolation. To date, 13 cases of MPS VI, 9 living and 4 now deceased, have been confirmed by clinical examination and genomic analysis, and each of these patients was shown to be homozygous for the ARSB p.H178L missense mutation.…”