Prenatal diagnosis of glucose-6-phosphate-dehydrogenase deficiency.

Prior to the development of the DNA-based technology reliable prenatal diagnosis of G6PD deficiency was not possible. We show that, using PCR amplification and restriction endonuclease digestion, prenatal diagnosis is possible. We have now been able to determine that the male fetus of a mother heterozygous for G6PD Mediterranean had inherited the maternal X chromosome with the normal G6PD gene.     

N-acetylglucosamine 6-sulphatase deficiency in a Nubian goat: A model of Sanfilippo syndrome type D (mucopolysaccharidosis IIID)

Summary A male Nubian goat (SD-1) presented at birth with neurological manifestations consistent with a lysosomal storage disease. Histological studies of tissue obtained at autopsy suggested glycosaminoglycan storage. Total urinary glycosaminoglycan levels, as measured by the uronic acid method, were elevated but overlapped with levels in a younger control goat. However,N-sulphate content was increased 2- to 5-fold, suggestive of heparan sulphate excretion, and this elevation was confirmed by cellulose acetate electrophoresis. Further, urinary levels of freeN-acetylglucosamine 6-sulphate were increased 6-fold over controls, SD-1 cultured skin fibroblasts, labelled with [³⁵S]sulphate, incorporated twice as much radioactivity into macromolecular material as did normal fibroblasts. Forty-eight hours after removal of [³⁵S]sulphate from the medium the SD-1 fibroblasts retained 58% of the label, whereas in control fibroblasts it had declined to 20%, indicative of [³⁵S]proteoglycan storage in SD-1. The assay of fibroblast extracts revealed a profound deficiency ofN-acetylglucosamine 6-sulphatase whereas eight other activities including-mannosidase, arylsulphatase B, iduronate 2-sulphatase,N-acetylgalactosamine 6-sulphatase, and heparin sulphamidase were normal. Mixing of SD-1 sonicates with normal sonicates showed no evidence of an inhibitor, and mixing of SD-1 sonicates with Sanfilippo D cell sonicates yielded no activity. These data ruled out multiple sulphatase deficiency and suggested the first example of the human Sanfilippo syndrome, type D (N-acetylglucosamine 6-sulphatase deficiency) in goats.     

Prenatal diagnosis for arginase deficiency: A case study

Arginase deficiency is a rare, autosomal recessive, disorder of the urea cycle characterized by mild hyperammonaemia, hyperargininaemia, dibasic aminoaciduria and orotic aciduria, associated with progressive spastic tetraplegia, seizures, psychomotor retardation, and growth failure. We report a family who presented with their daughter at 4 years 11 months of age with an acute encephalopathy. Initial laboratory results revealed hyperammonaemia (160 μmol/L; normal 0–34), hyperargininaemia (512 μmol/L; normal 23–86) and orotic aciduria. A diagnosis of arginase deficiency was confirmed by enzyme assay, and treatment with a modified protein-restricted diet along with sodium benzoate therapy was initiated. Over time, intellectual development has been normal, but the child developed spasticity in her lower extremities. Subsequently, the mother presented at 6 weeks of pregnancy seeking prenatal diagnosis. Prenatal testing for arginase deficiency has only been reported in one other case. Arginase is not expressed in cultured amniotic fluid cells or chorionic villus samples. Testing for arginase activity assay in red blood cells, isolated by cordocentesis, was performed and predicted an unaffected fetus. The result was confirmed by postnatal enzyme analysis of red cells from the newborn. On the basis of our experience, prenatal diagnosis of arginase deficiency by cord red blood cell arginase activity assay appears possible. This revised version was published online in August 2006 with corrections to the Cover Date.     

Prenatal diagnosis of triosephosphate isomerase deficiency

First-trimester prenatal diagnosis was undertaken by chorionic villus DNA analysis in two unrelated families with the inherited glycolytic disorder triosephosphate isomerase (TPI) deficiency. The propositus in each family was shown to be homozygous for a missense mutation (GAG --> GAC) at codon 104 of the TPI gene. In the first case the fetus was heterozygous for the codon 104 mutation and therefore clinically unaffected. Prenatal diagnosis in the second case showed the fetus to be homozygous for the codon 104 mutation and thus affected by TPI deficiency. This represents the first molecular diagnosis during early pregnancy of a human glycolytic enzyme disorder.     

Prenatal diagnosis of pyruvate kinase deficiency

Prenatal testing for pyruvate kinase deficiency is often requested by parents who already have an affected child. However, before the development of molecular biologic techniques there were no suitable diagnostic methods. We present here two cases in which the diagnosis was established, one using amniotic fluid cells, the other cord blood. Two different approaches were used. The first, using a direct method of PCR amplification and restriction endonuclease analysis, detected mutations in fetus genomic DNA. The second method, using two polymorphic sites linked to the PKRL gene, enabled us to establish which chromosome had been inherited from each parent.     

Prenatal and early postnatal treatment in 3-phosphoglycerate-dehydrogenase deficiency

3-phosphoglycerate-dehydrogenase (3-PGDH) deficiency is an L-serine biosynthesis disorder, characterised by congenital microcephaly, severe psychomotor retardation, and intractable seizures. We report prenatal diagnosis of an affected fetus by DNA mutation analysis. Ultrasound assessment showed a reduction in fetal head circumference from the 75th percentile at 20 weeks' gestation to the 29th percentile at 26 weeks. L-serine was then given to the mother, which resulted in an enlarged fetal head circumference to the 76th percentile at 31 weeks. At birth, the girl's head circumference was normal, and at 48 months' follow-up, her psychomotor development has been unremarkable. 3-PGDH deficiency is an inborn metabolic error that can be successfully treated antenatally.     

Laboratory testing for cobalamin deficiency in megaloblastic anemia

Cobalamin (vitamin B12) deficiency is a common cause of megaloblastic anemia in Western populations. Laboratory evaluation of megaloblastic anemia frequently includes the assessment of patient cobalamin and folate status. Current total serum cobalamin measurements are performed in the clinical laboratory with competitive binding luminescence assays, whose results may not always accurately reflect actual cobalamin stores. Surrogate markers of cobalamin deficiency such as methylmalonic acid and homocysteine have been utilized to improve diagnostic accuracy; however, the specificity of these tests by themselves is rather low. Measurement of the biologically active fraction of cobalamin, holotranscobalamin, has been proposed as a replacement for current total cobalamin assays. Although holotranscobalamin measurements appear to have slighter better sensitivity, the specificity of this assay remains to be determined. The relative merits and demerits of commonly available methods to assess cobalamin deficiency in patients with suspected megaloblastic anemia are discussed. Am. J. Hematol. 88:522–526, 2013. © 2013 Wiley Periodicals, Inc.     

Rationale for identification and susceptibility testing of anaerobic bacteria

Anaerobic bacteria are involved in a wide variety of human infections. In recent years there have been major refinements in technical materials used for transporting specimens, growing and identifying anaerobic bacteria and performing antimicrobial susceptibility tests. Because of the major importance of anaerobic bacteria and their changing susceptibility patterns, it has become increasingly important to identify these organisms and, in certain situations, to determine susceptibilities. The commercial availability of prereduced, anaerobically sterilized systems for identification has been helpful. However, the recent development of rapid identification systems based on tests for preformed enzymes has been a major advance. Finally, the commercial availability of broth microdilution susceptibility systems makes routine testing feasible. Guidelines for using these procedures are presented.     

Changes in incidence and sex ratio of glucose-6-phosphate dehydrogenase deficiency by population drift in Taiwan

We analyzed data from a single screening center in Taiwan from January 1, 1996 to December 31, 2005 to evaluate the change in incidence and female to male ratio of G6PD deficiency. During the study period, 1,211,632 of 2,667,922 (45.41%) neonates delivered in Taiwan were screened at the National Taiwan University Hospital. Of these, 21,997 neonates (1.82%) were confirmed to have G6PD deficiency. The annual incidence has decreased since 2002, from 1.94% to 1.61%. During this period, the male to female ratio in the screened population was 1.091 (range 1.073-1.098), the incidences in male and female neonates were 2.81% (2.57-3.07%), and 0.7% (0.45-0.95%), respectively. The change in sex ratio of the disease was unrelated to the change in incidence. During 2000-2005, 15-25% of newborns were born from newly immigrated females. G6PD deficiency screening has confirmed a subtle genetic flow in Taiwan. Besides the psychosocial effects, medical issues caused by population movements should be carefully watched in the future in Taiwan.     

A specific fluorogenic assay for N-acetylgalactosamine-4-sulphatase activity using immunoadsorption

Summary A method combining immune capture and enzyme detection by fluorochemistry has been developed for the diagnostic assay of N-acetylgalactosamine-4-sulphatase (4-sulphatase). The procedure uses a monoclonal antibody 4-S 4.1 to immunoadsorb 4-sulphatase specifically from complex protein samples containing other sulphatases, and 4-methylumbelliferyl sulphate to detect captured 4-sulphatase. The assay provides an accurate and simple method for the diagnosis of Maroteaux-Lamy syndrome (Mucopolysaccharidosis type VI).     

Screening and familial testing of patients for alpha 1-antitrypsin deficiency

alpha(1)-Antitrypsin deficiency (AATD) is an autosomal-codominant genetic disorder that predisposes individuals to the development of liver and lung disease. AATD is greatly underrecognized and underdiagnosed. Early identification allows preventive measures to be taken, the most important of which is the avoidance of smoking (including the inhalation of second-hand smoke) and exposure to environmental pollutants. Early detection also allows careful lung function monitoring and augmentation therapy while the patient still has preserved lung function. Cost factors and controversies have discouraged the initiation of large-scale screening programs of the newborn and adult populations in the United States and Europe (except for Sweden). There are sound medical reasons for targeted screening. Evidence-based recommendations for testing have been published by the American Thoracic Society/European Respiratory Society task force, which take potential social, psychological, and ethical adverse factors into consideration. This review discusses rationales for testing and screening for AATD in asymptomatic individuals, family members, and the general population, weighing benefits against potential psychological, social, and ethical implications of testing. For most, negative issues are outweighed by the benefits of testing. AATD testing should be routine in the management of adults with emphysema, COPD, and asthma with incompletely reversible airflow obstruction.     

Prenatal exposure to sex steroid hormones and behavioral/cognitive outcomes

Experimental studies in animals indicate that androgen exposure in fetal or neonatal life largely accounts for known sex differences in brain structure and behavior. Clinical research in humans suggests similar influences of early androgen concentrations on some behaviors that show sex differences, including play behavior in childhood and sexual orientation in adulthood. Available research also suggests that sex steroid hormone exposure may contribute to sex differences in the risk of autism and affective disorders in schizophrenia. However, findings have been inconsistent for other characteristics that show sex differences, including aggression and spatial ability. Moreover, social and environmental factors may modulate some of the associations observed. This article reviews the evidence that early-life exposure to sex steroid hormones contributes to sexually dimorphic behavior and cognitive abilities in humans.     

Fecal occult blood testing for iron deficiency: a reappraisal

Fecal occult blood (FOB) tests have been evaluated primarily for the application of colorectal cancer screening. Less is known about the performance characteristics of FOB tests for the evaluation of iron deficiency, the most common other application. As most clinically important occult gastrointestinal bleeding arises from the proximal gut, it is critical that FOB tests target analytes that are stable during the enteric transit. Available data indicate that guaiac-type and immunochemical tests are insensitive for the detection of proximal gut bleeding, and their use may confound the evaluation of iron deficiency. In contrast, the heme porphyrin test is sensitive for both proximal and distal sources of occult gastrointestinal bleeding, and this FOB test would appear to be the most rational selection for use in patients with iron deficiency or anemia. Outcome data are needed to better assess the impact of FOB testing on algorithms for evaluation of iron deficiency.     

Myoadenylate deaminase deficiency and forearm ischemic exercise testing

Myoadenylate deaminase (MADA) deficiency has been associated with symptoms of postexertional aches, cramps, weakness, and skeletal muscle dysfunction. Measurement of plasma lactate and ammonia concentrations after forearm ischemic exercise has been suggested as a screening test for this disorder. We performed forearm ischemic tests on 3 patients with histochemically defined MADA deficiency and 13 healthy control subjects, in a standardized fashion. Our results demonstrated that subject effort and/or performance during the exercise portion of testing is a critical variable. In addition to lactate and ammonia, plasma purine compounds (adenosine, inosine, and hypoxanthine) were measured. The finding of decreased purine release after exercise in MADA-deficient patients compared with that in normal individuals increases the specificity of the test and supports the hypothesis that disordered purine metabolism occurs in MADA deficiency.