Cyanotoxins in inland lakes of the United States: Occurrence and potential recreational health risks in the EPA National Lakes Assessment 2007.

A large nation-wide survey of cyanotoxins (1161 lakes) in the United States (U.S.) was conducted during the EPA National Lakes Assessment 2007. Cyanotoxin data were compared with cyanobacteria abundance- and chlorophyll-based World Health Organization (WHO) thresholds and mouse toxicity data to evaluate potential recreational risks. Cylindrospermopsins, microcystins, and saxitoxins were detected (ELISA) in 4.0, 32, and 7.7% of samples with mean concentrations of 0.56, 3.0, and 0.061µg/L, respectively (detections only). Co-occurrence of the three cyanotoxin classes was rare (0.32%) when at least one toxin was detected. Cyanobacteria were present and dominant in 98 and 76% of samples, respectively. Potential anatoxin-, cylindrospermopsin-, microcystin-, and saxitoxin-producing cyanobacteria occurred in 81, 67, 95, and 79% of samples, respectively. Anatoxin-a and nodularin-R were detected (LC/MS/MS) in 15 and 3.7% samples (n=27). The WHO moderate and high risk thresholds for microcystins, cyanobacteria abundance, and total chlorophyll were exceeded in 1.1, 27, and 44% of samples, respectively. Complete agreement by all three WHO microcystin metrics occurred in 27% of samples. This suggests that WHO microcystin metrics based on total chlorophyll and cyanobacterial abundance can overestimate microcystin risk when compared to WHO microcystin thresholds. The lack of parity among the WHO thresholds was expected since chlorophyll is common amongst all phytoplankton and not all cyanobacteria produce microcystins.

Two is better than one: a case of homozygous myotonic dystrophy type 1.

Myotonic dystrophy type 1 is an autosomal dominant condition caused by a trinucleotide CTG repeat expansion in the 3' untranslated region of the dystrophia myotonica protein kinase gene. The phenotypic features of myopathic facies, generalized weakness, and myotonia are thought to be dependent on repeat number, with larger expansions generally leading to earlier and/or more severe disease. The vast majority of individuals are heterozygous for an expanded allele and an allele in the normal range. In this clinical report, we describe two brothers with congenital myotonic dystrophy type 1. The younger of the two siblings is one of only 13 homozygous patients ever reported in the literature. He carries two expanded alleles: one with 1,170 repeats and the other with >100 repeats. We present his clinical picture in relation to his more severely affected heterozygous brother as well as other published homozygous cases. Finally, we discuss the inconsistency between repeat size and symptomatic expression as it applies to the current proposed mechanisms of myotonic dystrophy type 1 pathogenicity.

Positive cell-free fetal DNA testing for trisomy 13 reveals confined placental mosaicism.

PURPOSE: We report on a case in which cell-free fetal DNA was positive for trisomy 13 most likely due to confined placental mosaicism. Cell-free fetal DNA testing analyzes DNA derived from placental trophoblast cells and can lead to incorrect results that are not representative of the fetus. METHODS: We sought to confirm commercial cell-free fetal DNA testing results by chorionic villus sampling and amniocentesis. These results were followed up by postnatal chromosome analysis of cord blood and placental tissue. RESULTS: First-trimester cell-free fetal DNA test results were positive for trisomy 13. Cytogenetic analysis of chorionic villus sampling yielded a mosaic karyotype of 47,XY,+13[10]/46,XY[12]. G-banded analysis of amniotic fluid was normal, 46,XY. Postnatal cytogenetic analysis of cord blood was normal. Karyotyping of tissues from four quadrants of the placenta demonstrated mosaicism for trisomy 13 in two of the quadrants and a normal karyotype in the other two. CONCLUSION: Our case illustrates several important aspects of this new testing methodology: that cell-free fetal DNA may not be representative of the fetal karyotype; that follow-up with diagnostic testing of chorionic villus sampling and/or amniotic fluid for abnormal test results should be performed; and that pretest counseling regarding the full benefits, limitations, and possible testing outcomes of cell-free fetal DNA screening is important.

Genital anomalies in three male siblings with Simpson-Golabi-Behmel syndrome.

Simpson-Golabi-Behmel syndrome is an X-linked recessive overgrowth disorder characterized by prenatal onset of overgrowth, characteristic facies, and frequently mild to severe mental retardation. In addition, a number of other characteristics including supernumerary nipples, a grooved tongue or chin, chest wall malformations, and mild genital anomalies are frequently seen as well. Here we present three brothers with Simpson-Golabi-Behmel syndrome, all of which had cryptorchidism with one also having chordee of the penis, hypospadius, and penoscrotal transposition. While severe genital anomalies have been reported rarely in patients with Simpson-Golabi-Behmel syndrome, no individuals with such anomalies prior to this report had survived beyond the neonatal period.

Phenotypic variability in trisomy 13 mosaicism: two new patients and literature review.

Trisomy 13 mosaicism occurs when two cell lines, one with a normal complement of chromosomes and the other with an additional chromosome 13, are present in the same individual. We present two children with trisomy 13 mosaicism and summarize the literature in 47 published cases. Our first patient is a 4-year-old male with normal development and dysmorphic features that include right microtia, tall forehead, bulbous nose, and high arched palate. The second patient died at 1 day of life secondary to laryngeal stenosis, a previously undocumented finding in trisomy 13. His other dysmorphic features included micrognathia, cleft soft palate, and an axillary pterygium. Several published case reports of patients with trisomy 13 mosaicism have had the typical phenotype of complete trisomy 13 with death in the neonatal period, while others have had few dysmorphic features and prolonged survival. The most common malformations in all 49 cases included ear anomalies, cleft lip and palate, and various congenital heart defects. Intelligence varied from normal in six patients to significant delays and mental retardation in the remainder of cases. There is no clear correlation between the percentage of trisomic cells and the level of intellectual function. The dysmorphic features seen vary considerably from one patient to the next, often making the clinical diagnosis of trisomy 13 mosaicism difficult. In counseling families, medical professionals should state that trisomy 13 mosaicism may lead to physical abnormalities and poor intellectual outcomes, but that the condition does not do so universally with normal development occurring in some individuals.