Inbreeding effect on precocious mortality in Japanese communities of Brazil

Reproductive pattern in a rural Mediterranean population: La Alpujarra, Spain

The reproductive pattern of a sample of nuclear families from La Alpujarra (Andalusia, Spain) is analysed. The origin of the wife or consanguinity of the couple does not influence fertility. Variability in number of pregnancies is most closely associated with marriage duration followed by the wife's year of birth. Differences in the number of births are explained more by the number of pregnancies than by the number of miscarriages. The number of survivors to the first birthday is dependent on the number of births and to a lower extent on infant mortality. Data from incomplete families show that reproductive performance of the wife below the age of 45 cannot be accepted as a reliable estimate of complete reproduction.

The effect of consanguinity on the reproductive wastage in the Turkish population

Analysis of data from 56,664 marriages in Turkey studied from 1970 to 1988 showed an overall rate of consanguineous marriages, of 21.25%, and increases in the rates of abortions, stillbirths, prenatal losses and neonatal deaths.

Effects of consanguineous marriages on morbidity and precocious mortality: genetic counseling

The excess risks of morbidity and precocious mortality for the offspring of incestuous matings and of matings of uncles-nieces and aunts-nephews, first cousins, first cousins once removed, and second cousins have been estimated as 32%, 18%, 9%, 5%, and 2.5%, respectively. These estimates are based on the theory of Morton et al [1956], assuming a damage (genetic and nongenetic) of 20% for the offspring of nonconsanguineous couples and two "deleterious" equivalents per gamete. Other possibilities (a damage of 40%; 2.5 deleterious equivalents per gamete), a partition of the total risk into prenatal and postnatal events, and some aspects of the inbreeding theory are also presented. Comments intended for persons interested in counseling are provided.

Inbreeding effect on morbidity: III. A review of the world literature

A review of the international literature on the inbreeding effect on morbidity is presented. For anomalies in general, the estimates of B vary from 0.2 to 5.8, of A from 0.01 to 0.23, and of B/A from 3 to 77. The respective modal estimates are roughly around 0.5, 0.03, and 20. A review of the estimates for specific anomalies also shows a wide range of values; from B = 0.0008, A = 68 X 10(-8), and B/A = 1,176 (for acheiropodia) to B = 2.9, A = 0.24, and B/A = 12 (for "incapacity for military service"). Some estimates of B/A lower than 12 have been obtained for congenital malformations in some countries. An overall analysis of the whole body of data suggests that most of the anomalies are either entirely or predominantly mutational in origin.

Inbreeding studies in Brasilian schoolchildren

We present results of comparisons between consanguineous and control couples and their children in Southern Brasil. Multiple regression, t-test and chi 2 analyses were applied to the data. The following variables were investigated; Parents: structure of first cousin marriages, latitude and longitude of birthplaces, cohabitation time, rurality, marriage age, occupation, number of liveborn children, and frequency of twinning. Schoolchildren: clinical data as classified into 24 discontinuous traits, each one subdivided into two categories (number and severity), and seven continuous traits (weight, height, pulse rate, respiratory rate, systolic pressure, diastolic pressure, and temperature); nutrition indices and biotype; family names; intelligence tests and school performance; birth order, age, hair color, hair type, eye color, and skin color; twinning in the sibship, and infant mortality among sibs of the propositi. Our study showed a) nonrandomness of consanguineous marriages as detected on structural, racial, geographical, and temporal levels; b) a heavy mutational load of about 1.5 lethons acting on infant mortality; c) no inbreeding effect on morbidity in general (with a possible exception of "ear morbidity", including hearing deficit); d) a modest inbreeding depression on height (a decrease of 2 cm with an increase of 10% of inbreeding); 3) a suggestion of inbreeding depression on "intelligence".