Endoscopic surveillance for familial intestinal gastric cancer in low-incidence areas: An effective strategy

While clinical practice guidelines for hereditary diffuse gastric cancer are well established, there is no consensus on the approach for familial intestinal gastric cancer (FIGC). In low-incidence gastric cancer (GC) areas such as the United States or most European countries, there are no evidence-based recommendations on endoscopic assessment in FIGC families. We aim to describe the yield of GC surveillance in these families, and to identify epidemiological risk factors for the development of GC and its precursor lesions. This is a multicenter observational study involving nine tertiary Spanish hospitals, in which all individuals fulfilling FIGC criteria who underwent endoscopic surveillance were included between 1991 and 2020. Forty-one healthy individuals of 31 families were recruited. The median number of upper gastrointestinal endoscopies per individual was 3 (interquartile range, IQR, 1-4). The median interval time between tests was 2 years (IQR 1.5-2.5), and the median follow-up was 9 years (IQR 3-14.5). In 18 (43.9%) subjects, a precursor lesion of GC was found during follow-up, and in 2 (4.9%), an early GC was identified, in which curative treatment was offered. Helicobacter pylori (Hp) infection proved to be independently associated with an increased risk of developing precursor lesions or GC, adjusted by age, gender and follow-up, with an Odds Ratio of 6.443 (1.36-30.6, P value .019). We present the first outcomes that support endoscopic surveillance with biopsies and detection of Hp in FIGC families, although the periodicity has yet to be defined.

Mutational signature profiling classifies subtypes of clinically different mismatch-repair-deficient tumours with a differential immunogenic response potential

BACKGROUND

Mismatch repair (MMR) deficiency is the hallmark of tumours from Lynch syndrome (LS), sporadic MLH1 hypermethylated and Lynch-like syndrome (LLS), but there is a lack of understanding of the variability in their mutational profiles based on clinical phenotypes. The aim of this study was to perform a molecular characterisation to identify novel features that can impact tumour behaviour and clinical management.

METHODS

We tested 105 MMR-deficient colorectal cancer tumours (25 LS, 35 LLS and 45 sporadic) for global exome microsatellite instability, cancer mutational signatures, mutational spectrum and neoepitope load.

RESULTS

Fifty-three percent of tumours showed high contribution of MMR-deficient mutational signatures, high level of global exome microsatellite instability, loss of MLH1/PMS2 protein expression and included sporadic tumours. Thirty-one percent of tumours showed weaker features of MMR deficiency, 62% lost MSH2/MSH6 expression and included 60% of LS and 44% of LLS tumours. Remarkably, 9% of all tumours lacked global exome microsatellite instability. Lastly, HLA-B07:02 could be triggering the neoantigen presentation in tumours that show the strongest contribution of MMR-deficient tumours.

CONCLUSIONS

Next-generation sequencing approaches allow for a granular molecular characterisation of MMR-deficient tumours, which can be essential to properly diagnose and treat patients with these tumours in the setting of personalised medicine.

Quality of Colonoscopy Is Associated With Adenoma Detection and Postcolonoscopy Colorectal Cancer Prevention in Lynch Syndrome

BACKGROUND & AIMS

Colonoscopy reduces colorectal cancer (CRC) incidence and mortality in Lynch syndrome (LS) carriers. However, a high incidence of postcolonoscopy CRC (PCCRC) has been reported. Colonoscopy is highly dependent on endoscopist skill and is subject to quality variability. We aimed to evaluate the impact of key colonoscopy quality indicators on adenoma detection and prevention of PCCRC in LS.

METHODS

We conducted a multicenter study focused on LS carriers without previous CRC undergoing colonoscopy surveillance (n = 893). Incident colorectal neoplasia during surveillance and quality indicators of all colonoscopies were analyzed. We performed an emulated target trial comparing the results from the first and second surveillance colonoscopies to assess the effect of colonoscopy quality indicators on adenoma detection and PCCRC incidence. Risk analyses were conducted using a multivariable logistic regression model.

RESULTS

The 10-year cumulative incidence of adenoma and PCCRC was 60.6% (95% CI, 55.5%-65.2%) and 7.9% (95% CI, 5.2%-10.6%), respectively. Adequate bowel preparation (odds ratio [OR], 2.07; 95% CI, 1.06-4.3), complete colonoscopies (20% vs 0%; P = .01), and pan-chromoendoscopy use (OR, 2.14; 95% CI, 1.15-3.95) were associated with significant improvement in adenoma detection. PCCRC risk was significantly lower when colonoscopies were performed during a time interval of less than every 3 years (OR, 0.35; 95% CI, 0.14-0.97). We observed a consistent but not significant reduction in PCCRC risk for a previous complete examination (OR, 0.16; 95% CI, 0.03-1.28), adequate bowel preparation (OR, 0.64; 95% CI, 0.17-3.24), or previous use of high-definition colonoscopy (OR, 0.37; 95% CI, 0.02-2.33).

CONCLUSIONS

Complete colonoscopies with adequate bowel preparation and chromoendoscopy use are associated with improved adenoma detection, while surveillance intervals of less than 3 years are associated with a reduction of PCCRC incidence. In LS, high-quality colonoscopy surveillance is of utmost importance for CRC prevention.

The "diagnose and leave in" strategy for diminutive rectosigmoid polyps in Lynch syndrome: a post hoc analysis from a randomized controlled trial

BACKGROUND

The "diagnose-and-leave-in" policy has been established to reduce the risks and costs related to unnecessary polypectomies in the average-risk population. In individuals with Lynch syndrome, owing to accelerated carcinogenesis, the general recommendation is to remove all polyps, irrespective of size, location, and appearance. We evaluated the feasibility and safety of the diagnose-and-leave-in strategy in individuals with Lynch syndrome. METHODS : We performed a post hoc analysis based on per-polyp data from a randomized, clinical trial conducted by 24 dedicated colonoscopists at 14 academic centers, in which 256 patients with confirmed Lynch syndrome underwent surveillance colonoscopy from July 2016 to January 2018. In vivo optical diagnosis with confidence level for all detected lesions was obtained before polypectomy using virtual chromoendoscopy alone or with dye-based chromoendoscopy. Primary outcome was the negative predictive value (NPV) for neoplasia of high-confidence optical diagnosis among diminutive (≤ 5 mm) rectosigmoid lesions. Histology was the reference standard.

RESULTS

Of 147 rectosigmoid lesions, 128 were diminutive. In 103 of the 128 lesions (81 %), the optical diagnostic confidence was high and showed an NPV of 96.0 % (95 % confidence interval [CI] 88.9 %-98.6 %) and accuracy of 89.3 % (95 %CI 81.9 %-93.9 %). By following the diagnose-and-leave-in policy, we would have avoided 59 % (75/128) of polypectomies at the expense of two diminutive low grade dysplastic adenomas and one diminutive sessile serrated lesion that would have been left in situ.

CONCLUSION

In patients with Lynch syndrome, the diagnose-and-leave-in strategy for diminutive rectosigmoid polyps would be feasible and safe.

Risk of Cancer in Family Members of Patients with Lynch-Like Syndrome

Lynch syndrome (LS) is a common cause of hereditary colorectal cancer (CRC). Some CRC patients develop mismatch repair deficiency without germline pathogenic mutation, known as Lynch-like syndrome (LLS). We compared the risk of CRC in first-degree relatives (FDRs) in LLS and LS patients. LLS was diagnosed when tumors showed immunohistochemical loss of MSH2, MSH6, and PMS2; or loss of MLH1 with BRAF wild type; and/or no MLH1 methylation and absence of pathogenic mutation in these genes. CRC and other LS-related neoplasms were followed in patients diagnosed with LS and LLS and among their FDRs. Standardized incidence ratios (SIRs) were calculated for CRC and other neoplasms associated with LS among FDRs of LS and LLS patients. In total, 205 LS (1205 FDRs) and 131 LLS families (698 FDRs) had complete pedigrees. FDRs of patients with LLS had a high incidence of CRC (SIR, 2.08; 95% confidence interval (CI), 1.56–2.71), which was significantly lower than that in FDRs of patients with LS (SIR, 4.25; 95% CI, 3.67–4.90; p < 0.001). The risk of developing other neoplasms associated with LS also increased among FDR of LLS patients (SIR, 2.04; 95% CI, 1.44–2.80) but was lower than that among FDR of patients with LS (SIR, 5.01, 95% CI, 4.26–5.84; p < 0.001). FDRs with LLS have an increased risk of developing CRC as well as LS-related neoplasms, although this risk is lower than that of families with LS. Thus, their management should take into account this increased risk.

White-Light Endoscopy Is Adequate for Lynch Syndrome Surveillance in a Randomized and Noninferiority Study

BACKGROUND & AIMS

Dye-based pancolonic chromoendoscopy is recommended for colorectal cancer surveillance in patients with Lynch syndrome. However, there is scarce evidence to support its superiority to high-definition white-light endoscopy. We performed a prospective study assess whether in the hands of high detecting colonoscopists, high-definition, white-light endoscopy is noninferior to pancolonic chromoendoscopy for detection of adenomas in patients with Lynch syndrome.

METHODS

We conducted a parallel controlled study, from July 2016 through January 2018 at 14 centers in Spain of adults with pathogenic germline variants in mismatch repair genes (60% women; mean age, 47 ± 14 years) under surveillance. Patients were randomly assigned to groups that underwent high-definition white-light endoscopy (n = 128) or pancolonic chromoendoscopy (n = 128) evaluations by 24 colonoscopists who specialized in detection of colorectal lesions in high-risk patients for colorectal cancer. Adenoma detection rates (defined as the proportion of patients with at least 1 adenoma) were compared between groups, with a noninferiority margin (relative difference) of 15%.

RESULTS

We found an important overlap of confidence intervals (CIs) and no significant difference in adenoma detection rates by pancolonic chromoendoscopy (34.4%; 95% CI 26.4%-43.3%) vs white-light endoscopy (28.1%; 95% CI 21.1%-36.4%; P = .28). However, pancolonic chromoendoscopy detected serrated lesions in a significantly higher proportion of patients (37.5%; 95% CI 29.5-46.1) than white-light endoscopy (23.4%; 95% CI 16.9-31.4; P = .01). However, there were no significant differences between groups in proportions of patients found to have serrated lesions of 5 mm or larger (9.4% vs 7.0%; P = .49), of proximal location (11.7% vs 10.2%; P = .68), or sessile serrated lesions (3.9% vs 5.5%; P = .55), respectively. Total procedure and withdrawal times with pancolonic chromoendoscopy (30.7 ± 12.8 minutes and 18.3 ± 7.6 minutes, respectively) were significantly longer than with white-light endoscopy (22.4 ± 8.7 minutes and 13.5 ± 5.6 minutes; P < .001).

CONCLUSIONS

In a randomized parallel trial, we found that for Lynch syndrome surveillance, high-definition white-light endoscopy is not inferior to pancolonic chromoendoscopy if performed by experienced and dedicated endoscopists. ClinicalTrials.gov no: NCT02951390.

Chronic intestinal pseudo-obstruction: a diagnosis to be considered

Chronic intestinal pseudoobstruction (CIPO) is a rare entity characterized by recurrent clinical episodes of intestinal obstruction in which no mechanical cause is identified. There are multiple causes for this syndrome but two main groups can be distinguished: a) secondary to a systemic non-gastrointestinal disease; and b) primary or idiopathic originated from alterations in the components of the intestinal wall. The latter forms are the most uncommon and their diagnosis is generally difficult. In the present article, we describe nine patients with CIPO that were diagnosed in our center over the last six years. Four of them were diagnosed with primary or idiopathic form of CIPO and another four were clearly secondary to a systemic disease. The ninth case, which was initially diagnosed as secondary, is probably also a primary form of the disease. The number of patients diagnosed in our center, even thought small, makes us to hypothesize that the prevalence of CIPO is probably greater than is generally believed and that the reasons of its rarity are the incomplete understanding of its physiopathology and the difficulties to achieve a correct diagnosis.

Age trends of sibling resemblance for height, weight and BMI during growth in a mixed longitudinal sample from Sarsuna-Barisha, India

BACKGROUND

Even though some studies have considered that sibling resemblance remains constant throughout the life cycle, several investigations emphasize the importance of age and its interactions with genetic and environmental factors in determining sibling similarity in several bodily traits. In fact, the study of age changes in familial resemblance is of great importance for the analysis of certain sources of variation observed in growth processes.

AIM

The study examined sibling resemblance for height, weight and body mass index (BMI) in a mixed longitudinal sample from West Bengal, ages 2-19 years, in order to analyse the variations with age of the sibling resemblance for these phenotypes during growth.

SAMPLE AND METHODS

Two hundred and forty-five brothers and 213 sisters from 138 middle-class nuclear families living in a semi-urban area of South Kolkata, India were analysed. The analysis of sibling resemblance was performed through correlations estimated by the maximum-likelihood method. The patterns of different trends of sibling resemblance with age were examined by fitting a cubic non-linear regression to the observed correlations.

RESULTS

The results show clear variations with age in the sibling resemblance for the traits height and weight, though to a lesser extent for BMI. In general, we found the highest correlation values during the period of infancy, a remarkable decrease during puberty, and a trend of increase towards the end of the growth cycle.

CONCLUSION

The study confirms the effect of age on the degree of similarity among siblings for height, weight and BMI in the sample. The sharp decline of correlation at adolescence can be interpreted in terms of the individual variation in age of reaching the adolescent growth spurt.

Heritability of the somatotype components in Biscay families

The anthropometric somatotype is a quantitative description of body shape and composition. Familial studies indicate the existence of a familial resemblance for this phenotype and they suggest a substantial action by genetic factors on this aggregation. The aim of this study is to examine the degree of familial resemblance of the somatotype components and of a factor of shape, in a sample of Biscay nuclear families (Basque Country, Spain). One thousand three hundred and thirty nuclear families were analysed. The anthropometric somatotype components [Carter, J.E.L., Heath, B.H., 1990. Somatotyping. Development and applications. Cambridge University Press, Cambridge, p. 503] were computed. Each component was fitted for the other two through a stepwise multiple regression, and also fitted through the LMS method [Cole, T., 1988. Fitting smoothed centile curves to reference data. J. Roy. Stat. Soc. 151, 385-418] in order to eliminate the age, sex and generation effects. The three raw components were introduced in a PCA from which a shape factor (PC1) was extracted for each generation. The correlations analysis was performed with the SEGPATH package [Province, M.A., Rao, D.C., 1995. General purpose model and computer programme for combined segregation and path analysis (SEGPATH): automatically creating computer from symbolic language model specifications. Genet. Epidemiol. 12, 203-219]. A general model of transmission and nine reduced models were tested. Maximal heritability was estimated with the formula of [Rice, T., Warwick, D.E., Gagnon, J., Bouchard, C., Leon, A.S., Skinner, J.S., Wilmore, J.H., Rao, D.C., 1997. Familial resemblance for body composition measures: the HERITAGE family study. Obes. Res. 5, 557-562]. The correlations were higher between offspring than in parents and offspring and a significant resemblance between mating partners existed. Maximum heritabilities were 55%, 52% and 46% for endomorphy, mesomorphy and ectomorphy, respectively, and 52% for PC1. In conclusion, the somatotype presents a moderate degree of familial aggregation. For the somatotype components, as well as for PC1, the degree of familial resemblance depends on age. The sex only has a significant effect on ectomorphy.

Heritability variations of morphometric traits in West Bengal (India) children aged 4-19 years: a mixed-longitudinal growth study

BACKGROUND

Longitudinal and semi-longitudinal growth studies on siblings reflecting heritability changes during growth are very scarce. Moreover, studies of variables other than height, weight and BMI are virtually non-existent.

AIM

The study compared changes in the heritability of six body lengths, four body breadths, and three indices between ages 4 and 19 years on the basis of a mixed-longitudinal sample of siblings, and examined whether heritability estimates change during the growth period. The data consisted of 238 brothers and 214 sisters from 134 middle-class nuclear families living in Kolkata (India). The analysis of sibling correlation was performed by maximum likelihood. The age-related patterns of heritabilities of the various traits were described by a cubic spline.

RESULTS

The heritability was very high and significant in most traits, and at all considered ages. Mean heritability in the 10 morphometric traits was 69.3%, which was higher than the heritability values for the three indices.

CONCLUSIONS

These results confirmed the existence of age-related trends in heritability of the considered morphometric traits. The sharp decline of the heritabilities at adolescence in most of the morphometric traits, and the acromio-iliac index in particular, may be due to the large inter-individual variation in the age at which the adolescent growth spurt is reached in both sexes.

Tissue CA-19.9 content in colorectal adenomas and its value in the assessment of dysplasia

BACKGROUND

occasionally, the risk of malignant transformation may be difficult to establish in adenomatous polyps due to the fact that they contain areas with variable grades of dysplasia. A measurement of tissue tumor markers may be useful to recognize these adenomas.

OBJECTIVES

the aims of this study were: to established firstly the relationship between carbohydrate antigen 19.9 (CA-19.9) content in the colorectal mucosa and the characteristics of polyps, and secondly, the diagnostic value of the formers measurement.

PATIENTS AND METHODS

tissue CA-19.9 concentration was measured in 155 colorectal samples obtained from 145 patients (21 normal mucosa; 113 adenomatous polyps; 21 adenocarcinoma). Cytosol CA-19.9 content was determined by enzyme-linked immunoadsorbant assay, and the measurement of this protein was achieved by quantitative assay. Tissue samples were also processed for histological examination.

RESULTS

we demonstrated that CA-19.9 levels in adenomatous polyps and adenocarcinomas were significantly higher than in the normal mucosa. These levels varied significantly according to polyp size, histological type, and grade of dysplasia. CA-19.9 contents were higher in polyps with a high risk of malignant transformation than in those with a low risk of severe dysplasia. The cut-off value 214 U/mg of protein properly differentiated both types of risk. The area under the receiver operating characteristic (ROC) curves showed that cytosol CA-19.9 levels allow classifying polyps according to their histological features.

CONCLUSIONS

we concluded that the measurement of CA-19.9 content in adenomatous polyps may be useful to classify these tumors and confirm the feasibility to separate adenomas into two groups: low and high risk of malignant change.

Evidence of phenotypic and social assortative mating for anthropometric and physiological traits in couples from the Basque country (Spain)

This study examined 28 anthropometrical and physiological traits in 107 married couples living in the province of Biscay (Basque Country, Spain). The aim was to verify the existence of a phenotypic and/or social preference when choosing a mate. For this, correlations between pairs of spouses were estimated by maximum likelihood, and a model of familial transmission (path analysis) was applied in order to test if social homogamy between mates existed. The results provide significant evidence of phenotypic as well as social homogamy in several of the studied traits. Even if an assortment existed when choosing a mate for bony traits such as height, the effect of cohabitation cannot be discounted as the main causal factor for the high phenotypic resemblance observed between spouses for body composition traits. In addition, with the social homogeneity of the studied sample, significant evidence of the existence of social homogamy between mates was only found for 20% of the studied variables.

Genetic and environmental sources on familial transmission in Biscayan families – III. The dynamometric strength

The present research analyses a cross-sectional sample of 284 individuals (86 fathers, 86 mothers, 54 sons and 58 daughters) in 86 nuclear families living in the province of Biscay (Basque Country, Spain), with the aim of estimating both transmissible and non-transmissible components acting on familial resemblance for the maximum dynamometric strength of both hands, by means of a path analysis. Standardised data of each generation and sex were adjusted to a BETA model of path analysis independent of sex effects, allowing nevertheless the possibility to differentiate between transmissible (genetic and cultural) and non-transmissible (environmental) components acting on the observed phenotypic variance in Biscayan offspring. The results supported the full model of familial transmission for the two variables, in addition to other reduced models that gave rise to transmission effects regardless of any influence from the siblings' shared environment on the environmental transmitted component from their parents (b = 0), and without social homogamy between mates (u = 0). The most parsimonious model created, based on the previous ones, was accepted for both traits. The total transmissible variance (t2) explained between 21% (right hand) and 44% (left hand) of the observed phenotypic variation. These values are close to those from the literature (t2 = 37%). However, we should take into account that these kinds of estimations are specific for each group or population.

Genetic and environmental sources on familial transmission in Basque families. II. Stature, weight and body mass index

PRIMARY OBJECTIVE

The present research analyses a cross-sectional sample of 359 individuals (107 fathers, 107 mothers, 71 sons and 74 daughters) in 107 nuclear families from the Basque Country (Spain). The aim was the estimation of both transmissible and non-transmissible components acting on familial resemblance for stature, weight and body mass index (BMI).

METHODS

Standardized data of each generation and sex were adjusted to a BETA model of path analysis independent of sex effects, allowing the possibility of differentiating between transmissible (genetic and cultural) and non-transmissible (environmental) components acting on the observed phenotypic variance in Biscayan offspring.

RESULTS

The results supported the full model of familial transmission for the three variables, in addition to other reduced models that gave rise to transmission effects regardless of any influence from the siblings' shared environment on the environmental transmitted component from their parents (b = 0), and without genetic effects on the phenotype (h = z = 0). The most parsimonious model was accepted for weight and rejected for stature and BMI. The correlations existing between children and their mothers were higher than those with their fathers.

CONCLUSION

The results confirmed the hypothesis of maternal effects influencing the inheritance of stature.

Family resemblance for anthropometric traits. II. Assessment of maternal occupational and age effects

The present study was based on a cross-sectional sample of 1326 subjects (197 fathers, 466 mothers, 307 sons and 356 daughters) belonging to 488 nuclear families from the province of Biscay (Basque Country, Spain), with the purpose of estimating the degree of familial resemblance, for several anthropometric traits, by analysing the correlation coefficients between parent-offspring pairs. Height, weight, biacromial and bicrystal breadths, humerus and femur biepicondylar breadths, arm, waist and hip circumferences, biceps, triceps, subscapular, suprailiac, abdominal, thigh and calf skinfolds were taken from each individual. BMI, WHR and the sum of the seven skinfolds was computed. The mother's occupation and the age of offspring were taken into account, since the combination of all these factors might have an effect on familial resemblance. The mothers were classified into housewife (HM) and working mothers (WM). The offspring were divided into prepuberal, puberal and postpuberal subgroups. Standardised residuals were used to compute father-offspring (FO) and mother-offspring (MO) relations through correlation coefficients computed by maximum likelihood. The results confirm the influence of age on the correlations, since FO correlations revealed an increasing trend in HM's children for weight and another six variables as they grew older. On the other hand, the weight change tends to decrease with age in FO correlations within the WM group. Depending on mother's occupation and children's age, the global trend in the sample results in higher correlations in the second group (WM) than in the first one (HM) for the whole age range, but specially in FO correlations before puberty, where four variables (weight, bicrystal breadth, triceps and subscapular skinfolds) yield statistically significant differences.

Nutritional status by socioeconomic level in an urban sample from Bilbao (Basque Country)

Anthropometry, records of food intake, and bioelectric impedance were gathered from a sample of 297 adults of both sexes who lived in marginal districts in the town of Bilbao and benefited from a program of social assistance. This survey aimed to determine present nutritional status and to ascertain the relationship between food intake and nutritional conditions. A comparative evaluation of anthropometry and food intake was then carried out using a reference from the Basque Country and a control sample from the same area but from better-off nutritional and socioeconomic conditions. Males from low socioeconomic status (SES) displayed lower heights and weights compared to the local reference and control sample. They showed higher skinfold thickness than males in the local reference but lower thicknesses than those in the control sample. All anthropometric variables, except height, were higher in women of low socioeconomic status compared to the local reference and control sample. Low socioeconomic males had lower estimated percentage of body fat than the control sample, while females showed the opposite pattern. On the other hand, estimates of food intake in males did not reveal great differences among samples from different socioeconomic backgrounds, while low SES females had greater intakes of food than the better-off control sample. Estimated zinc intake showed differences by SES in both sexes.

Familial resemblance for the age at menarche in Basque population

A cross-sectional sample from Biscay province (Basque Country, Spain) composed of 296 subjects from 143 nuclear families was analysed. The aim of this research was to study familial resemblance for the age at menarche and to investigate the influence that BMI, fatness and several socio-familial variables have on the menarcheal age. The influence of these variables on the degree of similarity of mother-daughter and sister-sister pairs for the age at onset of menstruation will be determined. Mean ages at menarche of mothers estimated by retrospective methodology (12.88 years, SD = 1.57) and daughters assessed by probit analysis (12.34 years. SD= 1.00) showed no statistically significant differences. Mother-daughter and sister-sister correlations increased after controlling for BMI, fatness and several socio-familial variables (0.25 vs 0.36 and 0.28 vs 0.44, respectively). The results revealed the importance of BMI, fatness, socio-economic level and the number of people living together in the household on menarcheal age and on the estimation of correlations. However, no influence from sibship size (possibly because this variable is a part of the people living together in the household) nor from birth order of the subjects was observed.

Analysis of sibling resemblance in anthropometric somatotype components

We analysed the Heath-Carter somatotype familial resemblance degree in a sample of 1350 siblings (685 males and 665 females) from 634 nuclear families in the province of Biscay (Basque Country, Spain). Sibling correlations were estimated according to maximum likelihood procedures for endomorphy, mesomorphy, ectomorphy and somatotypical attitudinal distance (SADi), after having adjusted for age, sex and the two other components (Model I), and after taking into account several environmental variables shared by all members of each sibship (Model II). All sibling correlations of the somatotype components were significant, tending to be higher in the case of mesomorphy than in the case of endomorphy. Same-sex siblings (BB and SS) displayed significant mesomorphic and ectomorphic resemblances, but in the case of endomorphy, sisters (SS) revealed relatively low correlation compared with brothers (BB). The sex of sibs had a significant influence on correlations of mesomorphy, but not on the other two components. Further control of socio-familial variables such as the father's occupation and education, and the sibship size, resulted in lower mesomorphy correlation coefficients, but had no effect whatsoever on the other two components. SADi correlations were very low and not significant, indicating high degrees of dispersion in the individual somatotypes of the sample.

Sibling correlations of skin pigmentation during growth

The present study is focused on the analysis of skin color correlations in a sample of 1039 siblings aged 4 to 20 years from the province of Biscay (Basque Country, Spain). Measurements were taken at the upper inner arm and forehead by means of an EEL DS29 Digital Unigalvo reflectance spectrophotometer fitted with filters 601, 605, and 609. The reflectance data were internally standardized according to sex and age of the individuals, and the analysis of the degree of similarity between siblings was based on the calculation of intraclass correlation coefficients. All 3 filters gave fairly high and statistically significant correlations regarding forehead skin color (between 0.28 and 0.45) for all types of siblings under consideration. However, with respect to filter 609 the arm reflectance values did not reveal correlation either between brothers (0.01) or between siblings (0.02), even though it did reveal correlation between sisters (0.29). When other filters or type of sibling were considered (also for arm), all coefficients happened to be statistically significant and relatively high (0.35-0.43). This study confirms that the degree of sibling resemblance with regard to skin pigmentation is influenced by growth factors and that the upper inner arm and the forehead skin patterns change with age in the sense that, during and especially after puberty, the coefficients of correlation are higher for arm reflectance than for forehead reflectance; the forehead is a site that is more influenced by environment.

Age variations in sibling correlations for height, sitting height and weight

Familial correlations for height, sitting height and weight have been studied in a sample of 1278 siblings for the Biscay province (Basque Country), aged 4+ to 24+ years. The data have been internally standardized according to sex and age of individuals. The degree of resemblance among sibling has been expressed by intraclass correlation coefficients. The total sample has been divided into three age categories: < 12 years, 12-15 years, and > or = 15 years, in order to examine the effect of age on sibling correlations. In general, changes with age have been observed: sibling correlations for height show a clear upward trend through the considered growth period, reaching a value of 0.48 from 15 years of age. Intra-correlations for weight show a slight downward trend with age. Sitting height shows a rather low correlation before 12 years of age, but equally high values in the other two ranges of age (0.48 and 0.47, respectively). This study confirms that the sibling resemblance for the analysed trait fluctuated through the growth period--height and sitting height showing similar patterns of variation with age--and that, after puberty, the degree of genetic determination is higher for bone measurements than for weight.