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PubMed2006

Does marriage between first cousins have any predictive value for maternal and perinatal outcomes in pre-eclampsia?

AIM: To assess the consequences of consanguineous unions between first cousins on the severity of pre-eclampsia and associated perinatal morbidity. METHODS: Six hundred and eighty-six women admitted with a diagnosis of pre-eclampsia were included. The study group consisted of 62 preeclamptic women with a union between first cousins. The remaining patients admitted throughout the same period (n = 624) served as controls. The groups were compared regarding the presence of severe pre-eclampsia, hemolysis elevated liver enzymes low platelets (HELLP) syndrome, eclampsia, placental abruption, hematological complications, renal failure, requirement for antihypertensive or magnesium sulfate treatments, cesarean section for acute fetal distress, birthweight, Apgar scores, perinatal mortality and neonatal morbidity including admission to the neonatal intensive care unit, respiratory distress syndrome, sepsis, convulsions, intracranial hemorrhage, hypoglycemia, hypocalcemia, and jaundice. Student's t-test, chi(2)-test and logistic regression analysis were used for statistical evaluation. RESULTS: Univariate analysis yielded significant differences in parity (P = 0.034), maternal platelet counts (P = 0.02), and maternal serum potassium levels (P = 0.016) among the groups. Respiratory distress syndrome was more frequent (P = 0.043) in infants of unrelated couples. Multivariate analysis, controlling for the confounding factors, revealed that marriages between first cousins had no effect on any of our outcome variables including neonatal respiratory distress syndrome. CONCLUSIONS: Third-degree consanguinity in terms of a union between first cousins seems to have no effect on the development of maternal and perinatal complications in established pre-eclampsia.

Analysis of Variance↗

PubMed2004

Gender assignment in female congenital adrenal hyperplasia: a difficult experience.

OBJECTIVE: To report experience of gender (re)assignment in genotypic female (46XX) patients with congenital adrenal hyperplasia (f-CAH), a difficult and stressful experience if complicated with delayed presentation and inadvertent assignment. PATIENTS AND METHODS: Between 1983 and 2002, 70 patients with f-CAH were counselled for gender assignment. The age at diagnosis and operation, the degree of virilization, parental consanguinity, the gender preference of the families, and the factors governing the decision-making process were determined. RESULTS: Forty-one (59%) patients presented after the neonatal period. All parents had already assumed or were advised of a gender for their children, based on the suggestive appearance of the external genitalia. Consequently, 49 patients were reared as female and 21 as "male". Only nine of these "males" could be reassigned as females (mean age at presentation 7.87 months, sd 10.42). Twelve children had to be reared as "male"(mean age at presentation 55.8 months, sd 32.42) in compliance with the parents' and the study group's decision, and appropriate masculinizing reconstructive surgery was undertaken. The difference in the mean age of those reassigned as female and those who remained "male" was significant (P < 0.001). The parental consanguinity rate among the families was especially high in the 'male' patients. CONCLUSIONS It is extremely difficult to correct the gender of patients with f-CAH when they present at >2.5 years old. Furthermore, the delay in diagnosis and the male bias in choice of gender in our population might be a result of strong social pressures on families, influenced by cultural, traditional and economic factors.

Adrenal Hyperplasia, Congenital↗

PubMed2004

Clinico-epidemiological features of congenital nonbullous ichthyosiform erythroderma in the eastern province of Saudi Arabia.

BACKGROUND: A total of 10 455 new dermatology patients were seen in the dermatology clinics of King Fahd Hospital of the University (KFHU), Al-Khobar, Eastern Saudi Arabia, between January 1990 and December 1995. We identified 21 patients with a histopathologically confirmed diagnosis of congenital nonbullous ichthyosiform erythroderma (CNBIE). We have reviewed the epidemiological and clinical features of these patients. OBJECTIVE: To document the epidemiological and clinical features of patients with CNBIE in eastern Saudi Arabia. METHODS: We used the dermatology outpatient department (OPD) logbooks to identify diagnosed cases of CNBIE from new patients presenting with different dermatological problems over a 6-year period. We used specifically designed data-collection protocol forms to extract epidemiological and clinical data from the patients' medical records. These were entered into a computer database and analysed using standard statistical software. RESULTS: A total of 21 patients (five males, 16 females) with a male : female ratio of 0.31 : 1 were identified from a total of 10 455 new patients seen in our dermatology clinics over the study period. The occurrence rate of CNBIE in our clinics was 0.2%, or two per 1000 new dermatology cases. Nineteen (90%) of 21 CNBIE patients were born with collodion membranes. Eighty-one per cent of our patients had a positive family history of CNBIE. Consanguinity among the parents of our CNBIE patients was significantly high at 95%. CONCLUSIONS: To the best of our knowledge, this preliminary study is the first report of its kind from Saudi Arabia (documenting the clinico-epidemiological features of CNBIE patients in the Eastern Province). The high rate of parental consanguinity among the parents of our Saudi CNBIE patients may account for the high incidence rate of this genodermatosis in eastern Saudi Arabia. In comparison with results of other studies that reported a low occurrence rate of CNBIE among dermatology patients, our results were of a significantly higher rate.

Consanguinity↗

PubMed1983

Surnames in Sardinia. I. Fit of frequency distributions for neutral alleles and genetic population structure.

Distributions of surnames were examined using data from about 40 000 individuals from consanguineous marriages (1930-59) in the island of Sardinia. They fit the Karlin-McGregor (1967) distribution for neutral alleles. The logarithmic distribution by Fisher (1943) and the Karlin-McGregor (1967) distribution give practically indistinguishable fits to these data. The two parameters underlying the Fisher distribution, alpha and nu, are fully interdependent, given the sample size N. From the latter and from the number of surnames S, they can be easily and satisfactorily estimated. The quantity nu measures immigration to the area and can be taken as a measure of the richness of the gene pool, being closely related to the quantity theta = Nemu (Ne = effective population size, mu = mutation rate) after the necessary corrections have been taken care of. Surnames behave like genes transmitted by the male line. Differences of female and male migrations require correction for comparison with data from autosomal gene frequencies but there seem to be no important differences between female and male migration in this area, as judged by analysis of pedigrees of consanguineous marriages. It is probable that the migration estimates obtained in this material are lower than real ones, mostly because of a bias characteristic of the particular source of surnames here employed. The distribution of surnames from areas which have very recently undergone economic development is not at equilibrium and is not fitted as well as that of areas which have had less important recent changes. As might be expected, the disturbance is particularly marked in the class most sensitive to effects of recent increases in migration, that of rarest surnames (represented by only one individual). In fact in this material it is noticeable only in this class and correction can be made for it. At equilibrium of migration and drift, the number of surnames in a population sample of given size can give a complete description of the population structure for that sample, in the same sense that the number of alleles is a sufficient statistic for the study of neutral evolution. The study of surnames, given their nature of 'neutral' alleles, the large number of alleles and the ease with which large numbers of individual data can be collected, can be a valuable help in the study of genetic population structure.

Alleles↗

PubMed1989

Familiarity, recessivity and germline mosaicism.

In man evidence of autosomal recessive disease is usually based on a high sib risk, absence of parent-child transmission and increased consanguinity. Discrimination from what are sometimes termed multifactorial disorders and their associated environmental effects is usually based on the latter having a lower recurrence risk, an increased recurrence risk after a second affected child and no increase in consanguinity. Another cause of familial disorders with recurrence restricted to sibs which has received little attention is germline mosaicism for a mutation expressed as a dominant. If, for example, an embryonic mutation resulted in half the precursors of the germ cells carrying a mutation with dominant expression, then the proportion of haploid nuclei conveying the mutation, which is the recurrence risk, would be a quarter. If severity precluded reproduction the disorder would tend to be classified as a recessive. While germline mosaicism will rarely be expressed with such a high recurrence risk, the estimation of this risk in rare disorders is difficult due to extreme and unpredictable bias in ascertainment.

Consanguinity↗

PubMed1989

Inbreeding in the Utah Mormons: an evaluation of estimates based on pedigrees, isonymy, and migration matrices.

Using a computerized genealogical database, inbreeding coefficients were calculated for a sample of 435777 Utah Mormons. The population was divided into ten ten-year birth cohorts (1846-1945) and 22 geographic subdivisions in order to assess temporal and spatial variation in inbreeding. The average inbreeding coefficient for this population is 0.000 106. The average within-groups random kinship coefficient is 0.000 312, reflecting consanguinity avoidance. Random kinship matrices were formed by estimating the average kinship within each spatial subdivision and between all pairs of subdivisions. These matrices were compared statistically with kinship matrices previously estimated using migration matrices and isonymy data. The isonymy approach consistently overestimates random and total inbreeding as well as Wright's Fst. This can be attributed primarily to the assumption of monophyletic origin of surnames. The migration matrix method underestimates random inbreeding and Fst. This is due mainly to the assumption that outside immigrants are derived from a genetically homogeneous population. While the absolute values of the kinship coefficients estimated by each method differ substantially, the patterns of between-groups kinship coefficients given by each method are highly congruent. Logistic and linear regression analyses of 85,235 marriages demonstrate that consanguinity is significantly dependent upon year of marriage, geographic distance between husband's and wife's birthplaces, and the population size of husband's and wife's birthplaces.

Biometry↗

PubMed2006

Ignoring distant genealogic loops leads to false-positives in homozygosity mapping.

Distant consanguineous loops are often unknown or ignored during homozygosity mapping analysis. This may potentially lead to an increased rate of false-positive linkage results. We show that failure to take into account the distant loops may seriously underestimate the degree of consanguinity, especially for people from genetically isolated populations; in 6 Alzheimer's disease (AD) patients the distant loops accounted for 57.7 % of inbreeding on average. Theoretical evaluation showed that ignoring distant loops, which account for 18-75% of inbreeding, inflates the frequency of false positive conclusions substantially in 2-point linkage analysis, up to several hundred times. In multipoint linkage analysis of the 6 AD patients a chromosome-wide "empirical" significance of 5% corresponded to a true false positive rate of 11.1%. We show that converting multiple loops to a hypothetical loop capturing all inbreeding may be a convenient solution to avoid false positive results. When extended genealogic data are not available a hypothetical loop may still be constructed based on genomic data.

Alzheimer Disease↗

PubMed1996

Partial expression of the Papillon-Lefèvre syndrome in 2 unrelated families.

The Papillon-Lefèvre syndrome (PLS) is a rare, autosomal recessive trait that is characterized by palmar plantar keratosis (PPK) and severe, early onset periodontitis, affecting both deciduous and permanent dentitions. The clinical presentation of PLS is variable; the disease occurs so infrequently as to limit clinical cases for study. The exception is a few families with extensive consanguinity in which numerous cases occur. Of particular interest to mapping the genetic origin of the syndrome is the co-expression of the major traits of hyperkeratosis and periodontitis, and their severity. In this paper, we report 2 families with multiple affected individuals from geographically remote areas. A large extended family, from the Cochin region of India, currently residing in Israel, in which there is documented consanguinity and a family from the southwest region of Germany. In each family, 1 individual presents with hyperkeratotic lesions with the complete absence of periodontal lesions. Further, the difference in severity of the hyperkeratotic lesions between families is marked, and one sibling in the German family expressed rapid, early onset periodontitis in the absence of PPK. The genetic nature and penetrance of the genetic defect are discussed.

Adult↗

PubMed1983

Increased incidence of Glanzmann's thrombasthenia in Jordan as compared with Scandinavia.

12 Jordanian patients from 9 families with Glanzmann's thrombasthenia are described. All of them are products of consanguinous marriages. All cases are children with varying severity of mucosal bleeding. The clinical and laboratory findings are described. The importance of consanguinity is discussed and emphasized. Glanzmann's thrombasthenia is the second most common inherited haemorrhagic disorder in Jordan.

Adolescent↗

PubMed1986

Malformations in 10,000 consecutive births in Tunis.

Malformations were assessed in 10,000 consecutively born infants, dead or alive, at the Wassila Bourgiba Maternity Hospital in Tunis. The medical and social history including the rate of consanguinity was studied in the malformed group as well as in a control group of 229 infants. Three hundred and ninety-six infants were malformed; 248 had major malformations and 148 had minor ones. Thirteen per cent of the stillborn were malformed compared to 3.7% of the liveborn. The rates of most specific malformations were comparable to those in other studies but a relatively high rate of neural tube defects, 2.2/1000, can be noted. There is a significant overrepresentation of consanguinity (65%) in parents of non syndromic multi-malformed infants.

Abnormalities, Multiple↗

PubMed1997

Congenital adrenal hyperplasia in Turkey: a review of 273 patients.

In this study the clinical and epidemiological characteristics of congenital adrenal hyperplasia were evaluated retrospectively from the records of 273 patients managed in our clinic over a 25-year period. 21-Hydroxylase deficiency was present in 234 patients (85.7%), simple virilizing form in 134 (110 F, 24 M), salt-losing form in 85 (71 F, 14 M) and late on-set form in 15 girls. 11 beta-Hydroxylase deficiency was diagnosed relatively frequently (13.5%) among our patients with congenital adrenal hyperplasia; one girl had 17 alpha-hydroxylase deficiency and one boy had 3 beta-hydroxy steroid dehydrogenase deficiency. The median chronological age of diagnosis was 12 months (1 day-16.6 years) in patients with classical congenital adrenal hyperplasia. Chromosomal sex was 46, XX in a total of 221 patients and 46, XY in 52. Ninety-one girls were considered to be male before diagnosis was established and male sex was assigned in 31 of them due to development of male gender identity at diagnosis. Parental consanguinity rate among families of patients was higher than the general population in Turkey (56.4% vs 21%). Our overall figures show that the incidence of congenital adrenal hyperplasia is expected to be high due to a high rate of consanguinity in our populations and the patients remain frequently undiagnosed during the neonatal period. Therefore screening may be beneficial in our population.

Adolescent↗

PubMed1989

Type II hyperprolinaemia in a pedigree of Irish travellers (nomads).

We describe a study of 312 subjects in 71 families near related to a proband with type II hyperprolinaemia. The subjects were Irish travellers (nomads) among whom consanguineous marriage and high fertility are common. Thirteen additional cases of type II hyperprolinaemia were discovered; all were offspring of consanguineous unions. A further 50 subjects were found to have mild hyperprolinaemia. We found a strong association between type II hyperprolinaemia and seizures during childhood but no significant association with mental handicap. Most adults with type II hyperprolinaemia enjoyed normal health and there was no evidence that maternal hyperprolinaemia compromised fetal development. The documented association between type II hyperprolinaemia and seizures may be related to the neuromodulatory or reducing-oxidising effects of proline and pyrroline-5-carboxylate, respectively, that has been shown in vitro. Alternatively, another genetic defect closely linked to the type II hyperprolinaemia allele could be the explanation.

1-Pyrroline-5-Carboxylate Dehydrogenase↗

PubMed1985

Changing pattern of childhood blindness in Saudi Arabia.

We studied 187 patients attending special educational institutions in Saudi Arabia who were blind before the age of 14. All patients underwent complete ophthalmological evaluation. The visual acuity in 31% of the patients was no light perception and in 58% light perception to counting fingers at 3 feet (1 m). 70% were blind before age 2. Prior to 1962 acquired diseases led to blindness in 75% of the patients. From 1962 onwards genetically determined diseases accounted for 84% of childhood blindness. 56% of this group were the product of consanguineous marriages. On the other hand in the group who acquired blindness only 14% were from consanguineous marriages (p less than 0.0001). We here describe guidelines for the prevention of childhood blindness in Saudi Arabia.

Adolescent↗

PubMed2003

The familial contribution to non-syndromic ocular coloboma in south India.

AIMS: To identify the proportion of familial cases of isolated ocular colobomatous malformations in a case series from south India. METHODS: Children with ocular coloboma without systemic features were recruited from multiple sources in Andhra Pradesh, India. Their families were traced, pedigrees drawn, and family members examined. RESULTS: 56 probands, 25 females (44.6%) and 31 males (57.4%) with a colobomatous malformation were identified. In 12 cases (21.4%) another family member was affected. The risk to siblings was 3.8%. The parents were consanguineous in 25 cases (44.6%). CONCLUSIONS: 21.4% of cases of isolated ocular coloboma in this highly consanguineous population of south India were familial, with both autosomal dominant and autosomal recessive mechanisms likely in different families.

Adolescent↗

PubMed1987

Recurrence risks and prognosis in severe sporadic osteogenesis imperfecta.

A study was carried out in the United Kingdom of patients with severe osteogenesis imperfecta (OI), born with fractures to normal parents, in order to determine recurrence risks. A total of 105 cases from 98 families survived the perinatal period and 60 cases from 57 families were stillborn or died during the first week of life. The majority of the perinatal survivors correspond to the overlapping group of Sillence type III and sporadic type IV OI. In 40 of these, the radiograph at birth was available and in 37 it showed a characteristic appearance similar to that described previously for type III OI. The other three cases had radiological type IIB OI at birth and died before 26 months of age. The patients with perinatally lethal OI were subdivided on radiological appearance into Sillence type IIA (30 cases, described in the previous paper), type IIB (12 cases from 11 families), and type IIC (three cases from three families), and in five cases from three families the radiological appearance was the same as that of the 37 perinatal survivors described above. Ten cases from 10 families were not classified because their radiographs were unavailable. To analyse the empirical recurrence risks, patients were grouped according to radiological appearance at birth. Those with a type III-like pattern numbered 42 cases and they were grouped with the other cases of severe deforming OI who survived the perinatal period, for whom no x ray at birth was available, making a total of 107 cases. Taking one affected child per family as the proband, there were 98 probands. They had 146 sibs, of whom 10 were affected, giving an empirical recurrence risk of 6.9%. This is consistent with the disease arising as a new dominant mutation in about three quarters of families and as a recessive in about one quarter in this heterogeneous group. It is reasonable to give a recurrence risk of up to 25% in cases with parental consanguinity and a risk of 4.4% in cases with unrelated parents. Fifteen patients (14 probands) with Sillence type IIB OI had 13 sibs, one affected, giving an empirical recurrence risk of 7.7%. The parents were consanguineous in three families and the evidence for autosomal recessive inheritance for the majority in this group is probably stronger. The three patients with type IIC OI had three healthy sibs and the 10 unclassifiable perinatally lethal cases had 22 sibs, all normal. The radiological appearance at birth predicts prognosis to some extent; essentially, the better the bone morphology and mineralisation the longer the survival.

Consanguinity↗

PubMed1987

Homozygosity in piebald trait.

A severely affected child born to consanguineous parents is interpreted as being a homozygote for the dominantly inherited piebald trait. The striking phenotypic difference between the parents and the child implies intermediate inheritance of this condition, and the family also illustrates that consanguinity should not always be taken to indicate genetic heterogeneity and recessive inheritance.

Albinism↗

PubMed1994

Thalassaemia in Azerbaijan.

beta thalassaemia is present throughout the southern regions of the former USSR. We have defined the clinical picture of the disorder, the spectrum of beta thalassaemia mutations, and the role of customary consanguineous marriage in Azerbaijan, where thalassaemia presents a public health problem of the same order as that in Greece. Contrary to earlier suggestions, we found that the common form of the disorder is typically severe. Typical Turkish, Mediterranean, Azeri, Kurdish, and Asian Indian mutations were found, consistent with the history of the region. The common Mediterranean beta 0 thalassaemia mutation (codon 39) was not found. Three mutations (codon 8-AA, IVS2-1 and IVS1-110) account for over 80% of beta thalassaemia genes. Consanguineous marriage appears to contribute relatively little to the frequency of affected births. These observations provide the basis for a thalassaemia prevention programme in Azerbaijan.

Adolescent↗

PubMed1994

Apparent SMA I unlinked to 5q.

A proband with a clinical picture indistinguishable from SMA type I is described. The parents are second cousins. On DNA analysis it appeared that the proband and his healthy 2 year old sib had inherited the same haplotypes for DNA markers flanking the SMA locus on 5q. This supports non-linkage of SMA to chromosome 5q in this family. The consanguinity of the parents raises the possibility of a second locus for autosomal recessive SMA type I outside the 5q12-13 region. This may have implications for genetic counselling after prenatal diagnosis in consanguineous families. Furthermore, this case illustrates the importance of the inclusion of all healthy sibs in prenatal DNA studies for SMA type I.

Chromosomes, Human, Pair 5↗