Admixture and population stratification in African Caribbean populations

Throughout biomedical research, there is growing interest in the use of ancestry informative markers (AIMs) to deconstruct racial categories into useful variables. Studies on recently admixed populations have shown significant population substructure due to differences in individual ancestry; however, few studies have examined Caribbean populations. Here we used a panel of 28 AIMs to examine the genetic ancestry of 298 individuals of African descent from the Caribbean islands of Jamaica, St. Thomas and Barbados. Differences in global admixture were observed, with Barbados having the highest level of West African ancestry (89.6%+/- 2.0) and the lowest levels of European (10.2%+/- 2.2) and Native American ancestry (0.2%+/- 2.0), while Jamaica possessed the highest levels of European (12.4%+/- 3.5) and Native American ancestry (3.2%+/- 3.1). St. Thomas, USVI had ancestry levels quite similar to African Americans in continental U.S. (86.8%+/- 2.2 West African, 10.6%+/- 2.3 European, and 2.6%+/- 2.1 Native American). Significant substructure was observed in the islands of Jamaica and St. Thomas but not Barbados (K=1), indicating that differences in population substructure exist across these three Caribbean islands. These differences likely stem from diverse colonial and historical experiences, and subsequent evolutionary processes. Most importantly, these differences may have significant ramifications for case-control studies of complex disease in Caribbean populations.

Germline BCL-2 sequence variants and inherited predisposition to prostate cancer

Apoptosis is an essential physiological process that regulates cellular proliferation. Here, we explored the effect of DNA sequence variation within the BCL-2 gene on prostate cancer susceptibility in three clinical populations, consisting of 428 African Americans, 214 Jamaicans and 218 European Americans. We observed a 70% reduced risk for prostate cancer among the European Americans who had possessed two copies of a promoter variant -938C/A. Additionally, common BCL-2 haplotypes appeared to influence prostate cancer risk; however, studies in larger data sets are needed to confirm our findings. Our data suggest that inherited BCL-2 variants may be associated with a decrease in prostate cancer susceptibility.

Nondisjunction of chromosome 21

Chromosome heteromorphisms and restriction fragment length polymorphisms were used to study the origin of the extra chromosome in 54 trisomy 21 conceptuses. The parental origin was determined in 43 cases, with 39 (91%) being maternally and 4 (9%) parentally derived. Analysis of recombination demonstrated the presence of one or two cross-overs in most cases for which sufficient information was available, suggesting that failure to pair/exchange at meiosis I is relatively unimportant in the genesis of trisomy 21.

Survival of patients with SLE admitted to an intensive care unit—a retrospective study

We examined the demography, reasons for admission and cause of death in systemic lupus erythematosus (SLE) patients admitted to a medical intensive care unit (ICU) over a 7-year period. Fourteen patients were admitted during this period-all were female, 13 were of mixed ethnic ancestry and one a black South African. Of the 14 patients, 12 were admitted as a result of lupus activity, 2 had sepsis as the major cause of admission, although 5 other patients developed infection during their admission. Five patients had a generalised flare of their disease or progressive renal failure. Seven patients were admitted with a variety of lupus-related pathologies. In general the precise cause of death was difficult to determine. Of the 14 patients, 9 had impaired renal function on admission including 1 with sepsis and 1 of the survivors. Three patients (21%) survived, one with respiratory failure due to shrinking lung, a second with an acute flare of SLE and a third with pulmonary emboli. This study demonstrates that lupus in our community may produce life-threatening flares. Although cause of death was not always definitely identified, admission to the ICU was primarily due to active SLE and not sepsis or iatrogenic disease.

Evaluation of left ventricular enlargement in the lateral position of the chest using the Hoffman and Rigler sign

OBJECTIVE

To evaluate left ventricular enlargement in the lateral projection of the chest using the Hoffman and Rigler sign.

BACKGROUND

The Hoffman and Rigler sign for determining left ventricular enlargement was suggested as early as 1965 before the routine use of echocardiography.

METHODS

We studied 136 patients who had had cardiac ultrasound and chest X-rays with lateral projections. We assessed left ventricular size on the lateral projection using the Hoffman and Rigler method (measurement A) and compared this measurement to the value obtained by cardiac ultrasound. The effect of right ventricular size on this measurement was also evaluated. RESULTS The average value of measurement A in all patients with echocardiographic evidence of left vetricular enlargement (LVED above 59 mm) was 19 mm (SD +/- 4.03) (95% CI 17.96 to 20.04). Of the 48 patients with a normal size left ventricle on echocardiography, 25.58% had measurement A 18 mm and above, and 13.95% had a value 19 mm and above. Of the 19 patients with right ventricular enlargement (normal left ventricle) on echocardiography, 36.84% had measurement A18 mm and above, whereas 21.05% had this value 19 mm and above. Measurement A in patients with left ventricular enlargement compared with those with right ventricular enlargement showed a significant difference (p < 0.05).

CONCLUSIONS

When the crossing of the inferior vena cava and the left ventricle can be adequately visualised, the Hoffman and Rigler sign of evaluating left ventricular enlargement in the lateral projection of the chest is a valuable alternative where cardiac ultrasound is not readily available.

Prevalence of iron deficiency in 12-mo-old infants from 11 European areas and influence of dietary factors on iron status (Euro-Growth study)

A prospective longitudinal cohort study was performed to assess the prevalence of iron deficiency in European infants at 12 mo of age, and to study the influence of socio-economic status, dietary factors, growth and morbidity on iron status. The cohort consisted of 488 normal term infants from primary healthcare centres in 11 European areas. Assessed were socio-economic variables, dietary intake, anthropometry and morbidity at regular intervals from birth to 12 mo, and haemoglobin, serum ferritin, mean corpuscular volume, transferrin saturation and serum transferrin receptor concentrations at age 12 mo. The prevalence of anaemia was 9.4%, of iron deficiency 7.2%, and of iron deficiency anaemia 2.3%. More than 40% of anaemia was associated with normal iron status and associated with an increased frequency of recent infections. Iron deficiency anaemia was significantly more frequent with low (5.1%) than high socio-economic status (0%). Dietary factors accounted for most of this variation in multiple regression analysis. Early introduction of cows' milk was the strongest negative determinant of iron status. Feeding of iron-fortified formula was the main factor positively influencing iron status. Other dietary factors, including breastfeeding, did not play a significant role as determinants of iron status at age 12 mo. Conclusion. Iron deficiency anaemia is present in 2.3% of 12-mo-old European infants. The prevalence of iron deficiency anaemia varies strongly with socio-economic status. Avoidance of cows' milk feeding during the first year of life is the key measure in the prevention of iron deficiency.

Patterns of milk and food intake in infants from birth to age 36 months: the Euro-growth study

BACKGROUND

Little detailed information is available on feeding practices of infants in Europe. The Euro-Growth Study is a longitudinal, observational, multicenter study of milk feeding, the introduction of complementary solid foods, and vitamin and mineral supplementation. Current practice is compared with international feeding recommendations.

METHOD

Healthy term infants (n = 2,245) were recruited at birth or during the first month of life. Dietary records were completed at the ages 1, 2, 3, 4, 5, 6, 9, 12, 18, 24, 30, and 36 months by semiquantitative dietary recall.

RESULTS

At the age of I month, 52% of the infants were exclusively breast fed and 26% were exclusively formula fed. At the age of 9 months, 18% of infants were fed only cow's milk. At the ages of 3, 4, and 5 months, 50%, 67%, and 95% of infants were fed solid foods, respectively.

CONCLUSIONS

Feeding practices vary considerably throughout Europe. High rates of breast-feeding initiation are found in Umea, Sweden, and in Athens, Greece; and low rates in Dublin, Ireland, in Toulouse, France, and in Glasgow, United Kingdom. The use of cow's milk as the main milk drink before the age of 12 months is still common in certain European centers.

Wolf-Hirschorn syndrome resulting from partial monosomy 4p/trisomy 9p

An infant girl was referred for a genetic consultation because of facial appearance suggestive of Wolf-Hirschorn syndrome (WHS), growth retardation and generalized hypotonia. She had an unbalanced karyotype 46,XX,der(4)t(4;9)(p15.2;p22)mat resulting in the deletion of the critical region for WHS and duplication of the critical region for the 9p duplication syndrome. The mother and the grandmother of proposita were the carriers of an apparently balanced translocation 46,XX,t(4;9)(p15.2;p22). The infant's phenotype was characteristic of WHS syndrome rather than that of duplication 9p phenotype. This is probably the first description of WHS phenotype resulting from a familial 4;9 translocation.

De novo deletion 12q: report of a patient with 12q24.31q24.33 deletion

We report on a patient with de novo interstitial deletion of the long arm of chromosome 12: 46,XY,del(12)(q24.31q24.33). To our knowledge this is the first patient with this chromosomal abnormality reported. He was born with minor anomalies, ambiguous genitalia, tracheomalacia, and he was developmentally delayed at age 9 months. The phenotype associated with this deletion may be characteristic. However, because of the absence of reported cases of other patients with loss of this chromosomal region, we cannot delineate the specific phenotype further. Ambiguous genitalia or hypogonadism has been reported in other patients with chromosomal rearrangements involving 12q24.

Hypertension prevalence, awareness, treatment, and control among African Americans in the 1990s: estimates from the Maywood Cardiovascular Survey

During the last decade, the decline in cardiovascular disease mortality slowed among African Americans, compared to the general population. Hypertension control is likely to play an important role in determining these trends. The Maywood Cardiovascular Survey provides estimates of the prevalence, awareness, treatment, and control of hypertension among African Americans. Between 1991 and 1993, we conducted a cardiovascular disease survey among 1,524 African Americans living in the Chicago suburb of Maywood, Illinois. Estimates of the prevalence, awareness, treatment, and control of hypertension (defined as blood pressure [BP] > or = 140/90 mm Hg or self-reported taking of antihypertensive medications) were calculated and compared to U.S. population estimates for African Americans from NHANES II and III. The prevalence of hypertension in our sample was 32.7% (30.3, 35.1). After age-adjustment to the U.S. population, prevalence was 29.9% (27.9, 31.9), which is nonsignificantly lower than that reported for African Americans in NHANES III (32.4% [30.2, 34.6]). Awareness, pharmacologic treatment, and control on pharmacologic treatment were 81%, 56%, and 55%, respectively. These estimates are, respectively, 15%, 27%, and 42% higher than NHANES II and 7%, 9%, and 11% higher than NHANES III. Nonpharmacologic treatment alone may have accounted for up to 34% of hypertension control overall. Among previously diagnosed hypertensive subjects, risk factors for being untreated were male gender (odds ratio [OR] = 5.3 [1.3, 21.3]) and age < 45 years (OR = 3.8 [1.1, 12.8]), and for being uncontrolled was age > or = 65 years (OR = 1.9 [1.1, 3.0]). Rates of hypertension awareness, pharmacologic treatment, and control on pharmacologic treatment are higher in this sample of African Americans than among African Americans in NHANES II and are comparable to those in NHANES III. The impact of nonpharmacologic treatments on control needs further consideration. Medical Subject Headings (MeSH): hypertension, nonpharmacologic treatment, African-American males.

A comparative study of hypertension prevalence, awareness, treatment and control rates in St Lucia, Jamaica and Barbados

BACKGROUND

Cardiovascular diseases represent the most common cause of death in the English-speaking Caribbean, and hypertension represents the most important predisposing condition. However, direct between-country comparative studies in the Caribbean have not previously been undertaken.

OBJECTIVE

To obtain estimates of hypertension prevalence, awareness, treatment and control in three countries in the Caribbean.

DESIGN

Population-based samples of adults aged 25-74 years in St Lucia, Barbados and Jamaica were surveyed regarding their cardiovascular health and their blood pressures were measured using a highly standardized protocol. A reference site was available from a collaborative study among blacks in metropolitan Chicago, Illinois, USA.

RESULTS

At the 160/95 mmHg threshold, age-adjusted hypertension prevalence estimates for Jamaica, St Lucia and Barbados were 17.5, 18.3 and 21.5%, respectively, and 24.7, 26.9 and 27.9%, respectively, at the 140/90 mmHg threshold. The corresponding estimate for the Chicago site at the 140/90 mmHg threshold was 33.2%. The gradient in prevalence resembled the gradient in body mass index (25.7 kg/m2 in Jamaica to 29.3 kg/m2 in the USA). At the 160/95 mmHg threshold, the proportion of all hypertensives who were aware of their disease, pharmacologically treated and controlled was highest in Barbados (90, 85 and 72%, respectively) and lowest in St Lucia (74, 59 and 35%, respectively). Men, particularly those aged less than 55 years, were less likely to have their hypertension treated and controlled.

CONCLUSIONS

Compared with estimates from earlier independent surveys, considerable progress has been made in hypertension detection and control in these countries, which should lead to sizable reductions in the burden of cardiovascular disease.

Trisomy 21: association between reduced recombination and nondisjunction

To assess the association between recombination and nondisjunction of chromosome 21, we analyzed cytogenetic and DNA markers in 104 trisomy 21 individuals and their parents. Our DNA marker studies of parental origin were informative in 100 cases, with the overwhelming majority (94) being maternal in origin. This value is significantly higher than the 75%-80% maternal nondisjunction rate typically observed in cytogenetic studies of trisomy 21 and illustrates the increased accuracy of the molecular approach. Using the maternally derived cases and probing at 19 polymorphic sites on chromosome 21, we created a genetic map that spans most of the long arm of chromosome 21. The map was significantly shorter than the normal female linkage map, indicating that absence of pairing and/or recombination contributes to nondisjunction in a substantial proportion of cases of trisomy 21.