Genetic and environmental influences on blood pressure and physical activity: a study of nuclear families from Muzambinho, Brazil

Blood pressure (BP) and physical activity (PA) levels are inversely associated. Since genetic factors account for the observed variation in each of these traits, it is possible that part of their association may be related to common genetic and/or environmental influences. Thus, this study was designed to estimate the genetic and environmental correlations of BP and PA phenotypes in nuclear families from Muzambinho, Brazil. Families including 236 offspring (6 to 24 years) and their 82 fathers and 122 mothers (24 to 65 years) were evaluated. BP was measured, and total PA (TPA) was assessed by an interview (commuting, occupational, leisure time, and school time PA). Quantitative genetic modeling was used to estimate maximal heritability (h²), and genetic and environmental correlations. Heritability was significant for all phenotypes (systolic BP: h² = 0.37 ± 0.10, P < 0.05; diastolic BP: h² = 0.39 ± 0.09, P < 0.05; TPA: h² = 0.24 ± 0.09, P < 0.05). Significant genetic (r g) and environmental (r e) correlations were detected between systolic and diastolic BP (r g = 0.67 ± 0.12 and r e = 0.48 ± 0.08, P < 0.05). Genetic correlations between BP and TPA were not significant, while a tendency to an environmental cross-trait correlation was found between diastolic BP and TPA (r e = -0.18 ± 0.09, P = 0.057). In conclusion, BP and PA are under genetic influences. Systolic and diastolic BP share common genes and environmental influences. Diastolic BP and TPA are probably under similar environmental influences.

Estudo da funçäo tireóidea na síndrome de Down / Study of the thyroid function in Down syndrome

Os autores investigam o funcionamento da tireóide em 43 crianças com síndrome de Down e 48 controles em faixas etárias entre três meses e 18 anos, através de dosagens séricas de T3 livre (T3L), T4 L livre (T4L), tireotropina (TSH), T3 reverso (rT3) e anticorpos antimicrossomais (AcAM) e antitireoglobulina (AcAT). A idade óssea e as habilidades intelectuais também foram estimadas. Das 43 crianças com síndrome de Down, uma tinha hipotireoidismo clínico e em 12 havia hipotireoidismo subclíníco (27,9 por cento). A percentagem de AcAM titulável no grupo dos Down foi de 37,2 por cento. Em 25,6 por cento dos pacientes submetidos a radiografia de maos e punhos havia retardo na idade óssea. As médias hormonais dos casos de síndrome de Down sem disfunçao tireóidea detectável, quando comparadas às dos controles, mostraram-se significativamente mais elevadas quanto ao TSH e mais reduzidas quanto ao rT3. É possível que o déficit relativo de rT3 na síndrome de Down, confirmado neste trabalho, represente tao somente mais uma manifestaçao do hipotireoidismo. O rendimento intelectual dos casos de síndrome de Down com hipotireoidismo exclusivamente subclínico revelou-se comparável ao daqueles sem alteraçoes hormonais, embora o paciente com hipotireoidismo clínico mostrasse importante déficit mental. Crianças com síndrome de Down têm elevado risco de desenvolver hipotireoidismo, devendo portanto ser submetidas a estudos laboratoriais especializados, objetivando a prevençao de danos progressivos à funçao intelectual.