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PubMed1996

Inbreeding patterns in the Gredos Mountain Range (Spain).

The relationships among the frequency of consanguineous marriages, inbreeding coefficient, period, village size, and altitude are analyzed for three rural valleys belonging to the Sierra de Gredos (central Spain). These valleys occupy an area of about 30 x 80 km2, and the average total number of inhabitants for the period 1877-1970 was 58,621. Information about a sample of 23,744 weddings celebrated between 1875 and 1974 was obtained from 48 village parish registers. The mean inbreeding level up to second cousins for the whole area was 0.0012. A high percentage of inbreeding variation (83%) can be explained by each village's census size, resulting in a different interslope consanguinity pattern consisting of higher inbreeding levels in most northern localities in the Gredos mountains. This north-south geographic trend is consistent with results on blood polymorphisms from the same area (Mesa et al. 1994).

Altitude↗
PubMed1996

Retinitis pigmentosa genetics: a study in Indian population.

A total of 151 retinitis pigmentosa (RP) patients from 83 families were screened and the frequencies of different genetic categories studied. One hundred and ten patients out of 151 had a positive inheritance pattern, and autosomal recessive (AR) emerged as the predominant (53 out of 151), genetic pattern followed by isolated or sporadic (41 out of 151) cases. Further study of autosomal recessive cases revealed consanguinity as the main characteristic (49 out of 53) in the Indian population studied. Early onset and severe progression of disease was seen in the consanguineous group.

Consanguinity↗
PubMed1997

Epidemiology and etiology of hearing impairment among infants and children in a developing country. Part I.

OBJECTIVES: The study identifies children at risk for hearing impairment and determines the etiology, type, degree, and onset of deafness of Saudi children living in the city of Riyadh. The relationship to other anomalies is also explored, and a review of the literature is included. METHOD: This study features an extensive screening programme involving interviews, clinical and laboratory examinations, anthropometric and audiologic measurements, and family demographic data gathering of subjects both in the field and in clinics randomly selected throughout Riyadh. A control group of normal-hearing children was also selected. RESULTS: Of the 6421 children surveyed (55% male), aged 2 months to 12 years, the mean birth weight was 3050 g; the average number of siblings was 5.39; and the majority were from consanguineous families. Male children, lower birth weights, ocular problems, consanguinity, perinatal problems, lower socioeconomic level, and a family history of hearing impairment or other disease (e.g., meningitis) correlated with an increased risk of impairment in these children, as did the attendance of their mothers at an antenatal clinic. CONCLUSION: The study points to the significance of hearing impairment and its effect on communication and psychological and educational development, as well as the necessity for programmes to address these issues in children, both in management and prevention.

Child↗
PubMed1997

Inheritable and acquired hyperalgesia associated to abnormal opioid receptor set-up seem to act as opiate addiction preventors.

Hyperalgesia is known to depend on neuroplastic changes chiefly represented by long-term potentiation. These phenomena are proved to depend on excitatory amino acids (EAAs) action at the level of NMDA receptors. This action is known to be related to nitric oxide (NO) release. We found a visceral/vascular hyperalgesia state in migraine (M) sufferers as well as an inheritable systemic hyperalgesia in healthy subjects who are first-degree consanguineous with M sufferers; this type was labelled 'third hyperalgesia'. We discovered that a hyper-increase of plasma L-citrulline, equimolar co-product in the synthesis of NO, characterizes both M sufferers and their first-degree relatives who are exempt from primary headache. A similar pattern never occurred in healthy subjects having both a personal and family history negative for primary headache. We conclude that both 'third hyperalgesia' and a pattern of NO synthase (NOS) hyperactivity seems to be inheritable and can constitute, at least in part, a ground for developing headache. Morphine, proved to be unable to relieve M attack, was given in low doses that caused pain and side-effects in M sufferers only. This outcome seemingly indicates that M sufferers are characterized by a set-up of opioid receptor subtypes different from that of healthy headache-exempts. Following a period of morphine addiction and a withdrawal period, 65.07% of a group of 63 opiate addicts developed M syndrome. All these subjects were first-degree consanguineous relatives of primary headache sufferers. Discussion topics concern the activity of morphine in NO release and the role of NO in sensory transmission of both controls and hyperalgesia sufferers. It is suggested that the inheritable couple consisting of hyperalgesia and NOS hyperactivity can play some role in setting off the pain occurring following morphine in M sufferers.

Adult↗
PubMed1997

Acro-oto-ocular syndrome: further evidence for a new autosomal recessive disorder.

We report on a patient born to consanguineous parents and presenting with pseudopapilledema, mixed hearing loss, and minor facial and limb anomalies. To our knowledge, there is just one similar description of this syndrome in three members of a Brazilian kindred whose parents were also consanguineous, suggesting autosomal recessive inheritance. We compare the findings of our patient with these previous reported cases and discuss the differential diagnoses of this new syndrome, which we suggest be named the acro-oto-ocular syndrome.

Adolescent↗
PubMedDate not supplied

Juvenile and adult hemochromatosis are distinct genetic disorders.

Juvenile Hemochromatosis (JH) is a rare genetic disorder that causes iron overload. JH clinical features are similar to those of hemochromatosis (HFE), but the clinical course is more severe and is characterized by an earlier onset and by a prevalence of cardiac symptoms and endocrine dysfunctions. Here we describe seven Italian patients belonging to five unrelated families with clinical features typical of JH. In four out of five families the parents were consanguineous. Analysis of HFE gene mutations in all the cases and nucleotide sequence of the gene in one case excluded this gene as responsible for JH. Segregation analysis of 6p markers closely associated with HFE in families with consanguineous parents clearly showed that JH is unlinked to 6p and thus genetically distinct from HFE.

Adolescent↗
PubMed1997

Rett syndrome: the Swedish Genealogic Research Project. New data and present position.

Using the genealogical method on both classical and atypical cases of Rett syndrome (RS) the assumption that atypical RS are true variants of the classical or nuclear group of RS was investigated. Also common ancestry, common geographical origins, and consanguinity were investigated. The pedigrees of 96 classical and 32 atypical ("forme fruste") RS individuals were examined. None of the RS females was born to first-cousin couples, but 7.3 +/- 1.9% of the classical and 6.6 +/- 3.2% of the atypical RS females had grandparents who were consanguineous. Eleven or 34% of the atypical RS females and 49 or 51% of the classical RS females could be traced to the same small, separate "Rett area". Furthermore, no less than 6 (19%) of the atypical and 28 (29%) of the classical RS females had originated in the same homestead as another RS female examined by us. Nineteen of the explored pedigrees of RS females belonged to 8 pedigrees. The pedigrees contained a mixture of typical and atypical forms of RS indicating that many or most of the variants of RS and the classical types have a common genetic background. The data gathered suggest that transmission starts with a premutation that can result over generations in a full mutation giving rise to RS. Both the X-chromosomes and an autosome pair of chromosomes may be involved.

Consanguinity↗
PubMed1998

Ethnohistorical evidence for inbreeding among the pre-Hispanic Mixtec royal caste.

Pre-Columbian Mixtec social organization was distinguished by the tight endogamy of the ruling class, which included many consanguineous marriages. It was also characterized by a vigorous historical and genealogical tradition. The historical documents, or codices, provide materials for the calculation of the levels of inbreeding present before the Spanish Conquest. A genealogical analysis of inbreeding was performed on the combined pedigree, which spanned the tenth through sixteenth centuries, of all individuals connected by ancestry, descent, or marriage with Lord 8 Deer Jaguar Claw of Tilantongo (A.D. 1063-1115). Sixty of the 217 couples (27.65%) were consanguineous. When only couples of wholly known grandparentage were considered (N = 39), F = 0.1051. The mean F of all couples, even those where one spouse was of unknown parentage, was 0.0243. Over the 550 years of the pedigree the maximum F in any 52-year period was 0.1324. This level of inbreeding is sufficient to produce noticeable effects on population structure and affinities over time.

Consanguinity↗
PubMed1976

Estimating the risks for offspring of first-cousin matings. An approach.

Effects of parental consanguinity on morbidity and mortality can be estimated from observations on families ascertained through a child with a disease or defect, provided that appropriate corrections are made for the ascertainment bias. The risk of first-cousin parents having a child with a recessively inherited disease appears to be low (less than 1%). Data obtained by this approach suggest that the increased infant mortality associated with inbreeding (upon which calculations of lethal equivalents are based) may result in part from environmental differences between consanguineous and nonconsanguineous matings, which may be changing. Thus estimates of the number of lethal equivalents in a population can change as the environment changes.

Abortion, Spontaneous↗
PubMed1997

Hand and foot postaxial polydactyly: two different traits.

The aim of this work was to test whether postaxial hexadactyly had different clinical and epidemiological characteristics depending on hand or foot involvement. In the period 1967-1993, the Latin-American Collaborative Study of Congenital Malformations (ECLAMC) enrolled 1,582,289 births, and 2,271 cases with isolated (nonsyndromal) postaxial polydactyly (5th-digit hexadactyly). The prevalence was 14.3/10,000 births. Postaxial polydactyly (PP) of the hand (HPP) was the most frequent type (N:1,733; 76.3%; prevalence: 11.0/10,000), followed by foot PP (FPP=N:351; 15.5%; prevalence: 2.2), and hand and foot PP (BPP=N:187; 8.2%; prevalence: 1.2). Unlike HPP (55.0% bilateral; 77.2% left), FPP was less frequently bilateral (19.4%), with lower preference for the left side (55.5%). As expected, HPP was associated with African Black ethnicity, male sex, twinning, low maternal education, parental consanguinity, and there was frequent recurrence in 1st-degree relatives. Conversely, FPP was associated with Amerindian racial background, parental subfertility, and bleeding in the 1st trimester of pregnancy. BPP displayed the highest frequency of associated congenital defects (23.4%, vs HPP:6.6%, FPP: 15.4%). In its isolated form, BPP resembled HPP more than FPP with respect to left preference (90.9%), familial recurrence (11.0% of 1st degree relatives), and low maternal education. Although male sex preference and high frequency of twinning was observed in the 3 PP subtypes, statistical significance was present only in HPP. None of the 3 PP subtypes showed abnormal values for perinatal mortality, birth weight, length of gestation, parental ages, or parity. A logistic regression analysis showed Black race only to be associated with HPP, parental subfertility with FPP, parental consanguinity with BPP, and non-Black race with both FPP and BPP. The data presented here are the first indication that HPP and FPP are 2 different entities, with a larger genetic component in HPP than in FPP.

Ethnicity↗
PubMed1999

Heterotaxy-neural tube defect and holoprosencephaly occuring independently in two sib fetuses.

We report on two sib fetuses, products of a consanguineous union, who had multiple and apparently unrelated malformations. The first fetus, a female, had trilobed lungs, a single cardiac ventricle, asplenia, situs ambiguus of the liver, and a lumbosacral meningomyelocele. The brain of this fetus was normal. The second fetus, a male, had bilobed lungs, a single cardiac ventricle, situs solitus of the abdominal organs and spleen, and a semilobar holoprosencephaly. The occurrence of these malformations in sibs of different sexes and the parental consanguinity suggest a recessive mutation in a gene responsible for both heterotaxy and midline defects, including holoprosencephaly.

Female↗
PubMed1998

Familial aggregation of colorectal cancer in Egypt.

We have investigated the familial aggregation of colorectal cancer and hereditary nonpolyposis colorectal cancer (HNPCC) in Egypt because of the high incidence of colorectal cancer in Egyptian children and young adults and the prevalence of consanguinity there. In a pilot study, we conducted detailed interviews with 111 Egyptian colorectal cancer patients and 111 healthy Egyptian controls about their family histories of colorectal cancer, and other cancers, consanguinity, age at diagnosis, symptoms and recurrence. Eight patients (7.2%) had one or more first- or second-degree relatives under age 40 with colorectal cancer, suggestive of HNPCC by the Amsterdam criteria. One of these families had a typical history of HNPCC, with 4 relatives having colorectal cancer in 3 generations; 3 of these relatives were younger than age 45 at colon cancer diagnosis, and other relatives had extracolonic tumors. Another 14 patients (12.6%) had a first- or second-degree relative with a family history of other neoplasms such as endometrial, urinary and hepatobiliary cancers that could also be related to HNPCC. Four patients with early-onset colon cancer and a family history of other HNPCC-related cancers reported that their parents were first-degree cousins.

Adolescent↗
PubMed1996

Prenatal diagnosis of beta-thalassaemia and sickle cell anaemia in Turkey.

This paper reports our experience of molecular analysis and diagnosis of beta-thalassaemia and sickle cell anaemia (HbS) in 70 prospective parents of Turkish descent and their fetuses. Molecular screening was carried out by allele-specific oligonucleotide (ASO) hybridization of amplified DNA to the 12 most common mutations in the Turkish population. By using this approach, we were able to define the mutation in 95 per cent of chromosomes investigated. Genomic sequencing led to the additional detection of three rare mutations: Cd 44 (-C), IVS-I-5 (G-C), and IVS-I-116 (T-G). All diagnoses were successfully accomplished and no misdiagnosis occurred. Consanguineous marriage appears to contribute significantly to the frequency of affected births in Turkey. Out of the 14 homozygous fetuses, six were the result of close consanguinity. This study indicates that fetal diagnosis of beta-thalassaemia and HbS may be obtained in practically all cases, even in a heterogeneous population like the Turkish population, when early methods of fetal sampling are combined with polymerase chain reaction (PCR)-based techniques. Until gene therapy becomes a reality, the only approaches to the control of haemoglobinopathies are prevention and avoidance. The most relevant and common aspects of the programmes, which have been very effective in reducing the birth rate of beta-thalassaemia major in several at-risk areas of the Mediterranean basin, are the continuous educational campaigns directed at the population at large, the voluntary basis, and non-directive counselling. The most important challenge for the eradication of the haemoglobinopathies in Turkey is the organization of a nation-wide and comprehensive genetic preventive programme based on DNA technology.

Anemia, Sickle Cell↗
PubMed1998

Lethal neonatal autosomal recessive axonal sensorimotor polyneuropathy.

Peripheral neuropathy is an uncommon cause of generalized hypotonia and weakness in infancy. It occurs as a part of the clinical syndrome in some neurodegenerative disorders of infancy, but seldom causes respiratory failure or swallowing difficulties. We report a lethal autosomal recessive axonal polyneuropathy with neonatal onset in a large kindred from Northern Mississippi. One patient was studied in detail at our medical center and the information on 12 other affected infants in this large family were gathered from medical records and by interviewing the family members. Patients were symptomatic for the polyneuropathy before birth and died in the first year of life from respiratory complications. Thirteen babies were affected by this clinical phenotype in four generations of this family with a high frequency of consanguinity. Affected babies were of both sexes and were born to healthy consanguineous parents. The clinical phenotype of polyneuropathy in our index patient and other affected babies in this family was similar, and represents a unique form of hereditary neonatal polyneuropathy.

Age of Onset↗
PubMed1990

Immune deficiency in family members of patients with Hodgkin's disease.

Indirect data supporting a preexisting immunologic impairment in patients with Hodgkin's disease (HD) have been presented in recent years. These immunologic defects are supposed to be related to genetic and/or environmental factors. In this study, 65 first-degree relatives and 12 spouses of 21 consecutive patients with HD were studied immunologically. Furthermore, seven twin pairs in which one partner had HD and four additional nonmatched healthy co-twins were also included in the study. A decreased lymphocyte DNA synthesis induced by Concanavalin A, a high spontaneous DNA synthesis, or a low CD4+/8+ ratio was found in 21 (32%) consanguineous, two (17%) nonconsanguineous relatives, and five (50%) healthy co-twins. The corresponding figures for the untreated patients with HD and the control series were 14 of 21 (65%) and 21 of 127 (16%), respectively. Total lymphocyte counts or lymphocyte subpopulations did not differ between HD relatives and controls. The increased frequency of blood lymphocyte defects among consanguineous first-degree relatives favors the existence of a genetically determined immune deficiency in at least a proportion of apparently healthy relatives of patients with HD. However, nongenetic factors such as age and environment may add to the defect.

Adolescent↗
PubMed1981

Factor VII deficiency.

This report describes three patients with factor (F) VII deficiency: two adult siblings and an unrelated 5 1/2-month-old child who succumbed after several central nervous system (CNS) hemorrhages. This event prompted a review of the literature concerning the incidence and characteristics of intracranial hemorrhage in congenital F VII deficiency. Of 138 patients reported to have F VII deficiency, only 75 were considered to have a true deficiency. There was a 1:1 sex distribution with a 19% incidence of consanguinity in the 63 families which these 75 patients represented. CNS hemorrhage occurred in 12 of the 75 proven factor-deficient patients -- an incidence of 16.0%. There was a 1.4:1 female predominance in this group with a 44.4% incidence of consanguinity in their nine families. Except for one patient with hypertension, there was no history of preceding trauma or previous underlying CNS abnormality, though head trauma with a difficult vaginal delivery may have occurred in five infants. Diagnostic lumbar puncture or ventricular tap revealed bloody, xanthochromic cerebrospinal fluid in five. Five patients with F VII deficiency developed a CNS hemorrhage prior to 1 week of age, and none survived. Seven patients older than 1 week of age suffered such an event, and four of these survived. It is concluded that the greatest risk factor for development of CNS hemorrhage is trauma related to the birth process.

Adult↗
PubMed1987

Familial rhizomelic dysplasia: phenotypic variation or heterogeneity?

In a consanguineous kindred of mixed ancestry in Cape Town we observed a boy with severe shortness of stature and an unusual skeletal dysplasia with marked shortness of the humeri. A male one-half second cousin had gross abnormalities of the lower limbs, which were worst in the femora, but his skeleton was otherwise virtually normal. A brother and sister of this latter individual had been similarly affected and their parents were consanguineous. The question arises as to whether two similar but separate disorders are present in this family or whether the condition in these two persons represents extreme phenotypic variability of the same autosomal recessive entity.

Bone Diseases, Developmental↗