David K. Manchester

Possible association between maternal indomethacin therapy and primary pulmonary hypertension of the newborn

Indomethacin purportedly arrests premature labor by inhibiting the production of prostaglandins. Animal experimentation has demonstrated that prostaglandins are involved in the neonatal rerouting of the circulation. Experience with two neonates with disorders circulatory adjustment at birth following prenatal exposure to indomethacin indicates that indomethacin may interfere with these adjustments in man and favor the development of the serious oxygen dependency known as primary pulmonary hypertension of the newborn.

Recessive mutations in EPG5 cause Vici syndrome, a multisystem disorder with defective autophagy

Vici syndrome is a recessively inherited multisystem disorder characterized by callosal agenesis, cataracts, cardiomyopathy, combined immunodeficiency and hypopigmentation. To investigate the molecular basis of Vici syndrome, we carried out exome and Sanger sequence analysis in a cohort of 18 affected individuals. We identified recessive mutations in EPG5 (previously KIAA1632), indicating a causative role in Vici syndrome. EPG5 is the human homolog of the metazoan-specific autophagy gene epg-5, encoding a key autophagy regulator (ectopic P-granules autophagy protein 5) implicated in the formation of autolysosomes. Further studies showed a severe block in autophagosomal clearance in muscle and fibroblasts from individuals with mutant EPG5, resulting in the accumulation of autophagic cargo in autophagosomes. These findings position Vici syndrome as a paradigm of human multisystem disorders associated with defective autophagy and suggest a fundamental role of the autophagy pathway in the immune system and the anatomical and functional formation of organs such as the brain and heart.

Relationship between ambient air pollution and DNA damage in Polish mothers and newborns.

Industrialized regions in Poland are characterized by high ambient pollution, including polycyclic aromatic hydrocarbons (PAHs) from coal burning for industry and home heating. In experimental bioassays, certain PAHs are transplacental carcinogens and developmental toxicants. Biologic markers can facilitate evaluation of effects of environmental PAHs on the developing infant. We measured the amount of PAHs bound to DNA (PAH-DNA adducts) in maternal and umbilical white blood cells. The cohort consisted of 70 mothers and newborns from Krakow, Poland, an industrialized city with elevated air pollution. Modulation of adduct levels by genotypes previously linked to risk of lung cancer, specifically glutathione S-transferase MI (GSTM1) and cytochrome P4501A1 (CYP1A1) Msp restriction fragment length polymorphism (RFLP), was also investigated. There was a dose-related increase in maternal and newborn adduct levels with ambient pollution at the womens place of residence among subjects who were not employed away from home (p < or = 0.05). Maternal smoking (active and passive) significantly increased maternal (p < or = 0.01) but not newborn adduct levels. Neither CYP1A1 Msp nor GSTM1 polymorphisms was associated with maternal adducts. However, adducts were significantly higher in newborns heterozygous or homozygous for the CYP1A1 Msp RFLP compared to newborns without the RFLP (p = 0.04). Results indicate that PAH-induced DNA damage in mothers and newborns is increased by ambient air pollution. In the fetus, this damage appears to be enhanced by the CYP1A1 Mspl polymorphism. ImagesFigure 1

Sensitivity of human placental monooxygenase activity to maternal smoking

The in vitro oxidation of 7‐ethoxyresorufin was studied in placental microsomes from 47 full‐term pregnancies. Placental activities were compared in four groups formed on the basis of maternal smoking history as follows: nonsmokers (n = 12), passive smokers (n = 16), 1 to 20 cigarettes/day (n = 13), and 20+ cigarettes/day (n = 5). Passive smoking was defined as living with someone who smoked cigarettes. Umbilical cord plasma thiocxanate concentrations were measured to confirm histories and were higher when mothers smoked (80 ± 10 μM, 1 to 20 cigarettes/day, 116 ± 8 μM, 20+ cigarettes/day) than when mothers did not smoke (34 ± 3 μM, nonsmokers; 35 ± 3 μM, passive smokers). 7‐Ethoxyresorufin O‐deethylase activity was increased 10‐ to 30‐fold in placentas from smokers. Activity toward 7‐ethoxyresorufin in placentas from smokers was markedly inhibited in vitro by addition of 7,8‐benzofiavone. Among nonsmokers, percent inhibition of O‐deethylase activity by 7,8‐benzoflavone was greater (P < 0.05) in placentas from women passively exposed to cigarette smoke. Human placental monooxygenase activity is sensitive to both active and passive cigarette smoke exposure.

Use of the Internet by patients and their families to obtain genetics-related information

OBJECTIVE To characterize use of the Internet by patients and their families referred to general genetics clinics. PATIENTS AND METHODS We developed a survey to assess Internet use among patients visiting urban and rural clinics in Colorado and Wyoming. One hundred eighty-nine surveys were distributed to patients and their family members visiting outpatient general genetics clinics in spring 2000. The 8-page anonymous survey instrument asked about use of the Internet to obtain genetics-related information (GRI). All participants were asked whether a physician or health professional had referred them to the Internet for GRI. Subjects who had previously used the Internet to search for GRI were asked to rate whether they considered the GRI they encountered to be accurate, inaccurate, easy to understand, confusing, or trustworthy. RESULTS One hundred fifty-seven surveys (83%) were returned (52% urban; 48% rural). Ninety (60%) of 149 respondents were at the clinic for a new-patient visit, and 59 (40%) were follow-up visits. All respondents were older than 17 years; 141 (91%) of 155 respondents were the patients parent or guardian. Seventy-three (47%) of 155 respondents had searched the Internet for GRI prior to their clinic visit. The patients and families themselves initiated the majority of such efforts; only 8 (5%) of 148 respondents had been referred to a site on the World Wide Web by a physician. Interestingly, 136 (92%) of 147 respondents indicated that they would be likely to visit a Web site that was recommended by a geneticist. The most compelling reasons for searching the Internet for GRI were to get information in laypersons terms (60/131 [46%]); to get information about treatment (16/131 [12%]); and to get information about genetic research (16/131 [12%]). Among respondents who reported visiting GRI Web sites, 24 (41%) of 58 agreed that information was confusing or difficult to understand, 35 (53%) of 66 agreed that information was accurate and trustworthy, and 44 (77%) of 57 agreed that using the Internet was a positive experience. CONCLUSION Internet use among patients referred to general genetics clinics and their family members appears to be widespread. Respondents reported that they found some of the information confusing and questioned its accuracy. Referral to Web sites by physicians was reported rarely, although the majority of respondents said they would visit a Web site recommended by a genetics physician. Further studies are needed to establish the accuracy of Internet information and how best to integrate and/or accommodate the data into the genetics clinic.

Mutations in the δ-sarcoglycan gene are a rare cause of autosomal recessive limb-girdle muscular dystrophy (LGMD2)

ABSTRACTThe dystrophin-based membrane cytoskeleton of muscle fibers has emerged as a critical multiprotein complex which seems to impart structural integrity on the muscle fiber plasma membrane. Deficiency of dystrophin causes the most common types of muscular dystrophy, Duchenne and Becker muscular dystrophies. Muscular dystrophy patients showing normal dystrophin protein and gene analysis are generally isolated cases with a presumed autosomal recessive inheritance pattern (limb-girdle muscular dystrophy). Recently, linkage and candidate gene analyses have shown that some cases of limb-girdle muscular dystrophy can be caused by deficiency of other components of the dystrophin membrane cytoskeleton. The most recently identified component, δ-sarcoglycan deficiency occurred in other world populations, to identify the range of mutations and clinical phenotypes, and to test for the biochemical consequences of δ-sarcoglycan gene mutations, we studied Duchenne-like and limb-girdle muscular dystrophy patients who we had previously shown not to exhibit gene mutations of dystrophin, α-, β-, or γ-sarcoglycan for δ-sarcoglycan mutations (n = 54). We identified two American patients with novel nonsense mutations of δ-sarcoglycan (W30X, R165X). One was apparently homozygous, and we show likely consanguinity through homozygosity for 13 microsatellite loci covering a 38 cM region of chromosome 5. The second was heterozygous. Both were girls who showed clinical symptoms consistent with Duchenne muscular dystrophy in males. Our data shows that δ-sarcoglycan deficiency occurs in other world populations, and that most or all patients show a deficiency of the entire sarcoglycan complex, adding support to the hypothesis that these proteins function as a tetrameric unit.

Maternal Smoking Increases Xenobiotic Metabolism in Placenta but Not Umbilical Vein Endothelium

ABSTRACT. It is unclear whether placental xenobiotic metabolism can protect the human conceptus. In particular, the role of placental metabolism of toxic components of cigarette smoke such as polycyclic aromatic hydrocarbons (PAHs) is poorly understood. We hypothesized that increased aryl hydrocarbon hydroxylase (AHH) activity observed in placentas from smokers might help clear PAHs from maternal circulation and thereby prevent transplacental induction of AHH by PAHs. Our studies of AHH activity in human placentas and umbilical vein endothelium support this premise. While AHH activity was significantly increased in placentas from smokers compared with activity in placentas from nonsmokers, AHH activity in umbilical vein endothelium from these same pregnancies was unaffected by maternal smoking and remained low. In order to confirm that AHH present in endothelium was inducible, we also demonstrated dose-dependent increases in AHH activity in primary cultures of human umbilical vein endothelial cells exposed to PAHs. These findings may indicate first pass protection of the fetus by placental xenobiotic metabolism, or that endogenous factors suppress AHH induction in the fetus but not placenta.ABSTRACT. It is unclear whether placental xenobiotic metabolism can protect the human conceptus. In particular, the role of placental metabolism of toxic components of cigarette smoke such as polycyclic aromatic hydrocarbons (PAHs) is poorly understood. We hypothesized that increased aryl hydrocarbon hydroxylase (AHH) activity observed in placentas from smokers might help clear PAHs from maternal circulation and thereby prevent transplacental induction of AHH by PAHs. Our studies of AHH activity in human placentas and umbilical vein endothelium support this premise. While AHH activity was significantly increased in placentas from smokers compared with activity in placentas from nonsmokers, AHH activity in umbilical vein endothelium from these same pregnancies was unaffected by maternal smoking and remained low. In order to confirm that AHH present in endothelium was inducible, we also demonstrated dose-dependent increases in AHH activity in primary cultures of human umbilical vein endothelial cells exposed to PAHs. These findings may indicate first pass protection of the fetus by placental xenobiotic metabolism, or that endogenous factors suppress AHH induction in the fetus but not placenta.

Harnessing genomics to identify environmental determinants of heritable disease

Next-generation sequencing technologies can now be used to directly measure heritable de novo DNA sequence mutations in humans. However, these techniques have not been used to examine environmental factors that induce such mutations and their associated diseases. To address this issue, a working group on environmentally induced germline mutation analysis (ENIGMA) met in October 2011 to propose the necessary foundational studies, which include sequencing of parent-offspring trios from highly exposed human populations, and controlled dose-response experiments in animals. These studies will establish background levels of variability in germline mutation rates and identify environmental agents that influence these rates and heritable disease. Guidance for the types of exposures to examine come from rodent studies that have identified agents such as cancer chemotherapeutic drugs, ionizing radiation, cigarette smoke, and air pollution as germ-cell mutagens. Research is urgently needed to establish the health consequences of parental exposures on subsequent generations.

EPG5-related Vici syndrome: a paradigm of neurodevelopmental disorders with defective autophagy

Vici syndrome is a progressive neurodevelopmental multisystem disorder caused by mutations in the autophagy gene EPG5. Byrne et al. characterise the phenotype of 50 affected children, revealing callosal agenesis, cataracts, hypopigmentation, cardiomyopathy, immune dysfunction, developmental delay and microcephaly. Downregulation of epg5 in Drosophila results in autophagic abnormalities and progressive neurodegeneration.

Range of environmentally responsive monooxygenase activities in human placental microsomes determined by direct fluorescence techniques

Abstract Two direct fluorometric assays of in vitro xenobiotic oxidation have been adapted for use with placental microsomes. A total of 103 placentas were studied. NADPH-dependent disappearance of benzo[a]pyrene was found in the majority of placental preparations from pregnancies in which maternal smoking had occurred, but was observed only rarely in its absence. O -Deethylation of 7-ethoxyresorufin (ERR) was demonstrable in all cases. O -Deethylase activity correlated positively with benzo[ a ]pyrene disappearance ( r = 0.87 ± 0.16) when mothers smoked cigarettes and was significantly higher than activity in preparations from nonsmokers. A shift in apparent K m toward ERR from 10 −5 M to 10 −7 M was observed as a consequence of maternal smoking. Addition of α-naphthoflavone markedly inhibited O -deethylation in induced placentas, whereas stimulation of in vitro metabolism occurred in noninduced placentas. These results establish operational definitions of induction in human placental monooxygenase systems and provide a basis for quantitative descriptions of fetal environmental responses.