Undiagnosed maternal phenylketonuria: the need for prenatal selective screening or case finding.

OBJECTIVES: The aims of this article are to report on a review of cases of maternal phenylketonuria in the International Maternal Phenylketonuria Collaborative Study that were initially diagnosed during or after a pregnancy, to alert health care practitioners to the possible existence of women with undiagnosed phenylketonuria whose fetuses are at risk, and to emphasize that not all adults with untreated phenylketonuria are mentally retarded. STUDY DESIGN: The study was conducted through retrospective database review. RESULTS: Of 414 women with live-born infants, 17 fulfilled our criteria. Six had phenylketonuria diagnosed after they had produced >/=1 affected offspring, 2 had phenylketonuria diagnosed as a result of transient postnatal hyperphenylalaninemia in an offspring, and 9 had phenylketonuria diagnosed by prenatal screening. Undiagnosed maternal phenylketonuria in North America and Europe is currently estimated at 1 case/100,000 births; this rate could be higher elsewhere. CONCLUSIONS: Physicians and midwives should consider a protocol of selective prenatal screening or case finding to detect undiagnosed phenylketonuria among their patients.

German Maternal Phenylketonuria Study.

The German maternal phenylketonuria (MPKU) Study began in 1989 and since 1992 works together with the American-Canadian MPKU Study. Main goals of the study are: (1) to find women with phenylketonuria (PKU) and mild untreated hyperphenylalaninaemia (HPA); (2) to inform them about the risks of an untreated pregnancy with PKU and HPA; (3) to evaluate the efficacy of the phenylalanine (Phe) restricted dietary treatment prior to and during pregnancy by following the physical and cognitive development of offspring from treated pregnancies. An interim report of the study is presented. Until now, 43 pregnancies have been followed. They resulted in 34 live births, 24 from women with PKU and 10 form women with HPA. There are significant negative correlations between the gestational age in which the dietary control (blood Phe level < 360 mumol/l) was reached and pregnancy outcome as measured by growth parameters and early cognitive and motor developmental quotients at the age of 2 years. For minimizing risks of MPKU, preconceptional dietary control is strongly recommended. Tracking and timely information of young women about risks of MPKU is of outmost importance.

Mutations of the iduronate-2-sulfatase (IDS) gene in patients with Hunter syndrome (mucopolysaccharidosis II).

Genomic DNA and cDNA from fibroblasts from nine unrelated German patients with X-linked iduronate-2-sulfatase (IDS) deficiency showing variable clinical manifestation were screened for point mutations and small structural aberrations. Direct sequencing revealed a splice mutation skipping exon A, one nonsense mutation, and five missense mutations concerning the exons B, F and I of the IDS gene. Several novel missense mutations were found: A68E, S426X, I485R, Q293H, and D478G. One of the point mutations eliminating a recognition site for the restriction enzyme MspI was used as a direct marker for a prenatal diagnosis. A relationship between type of mutation and clinical picture could not be recognized.

Results of selective screening for inborn errors of metabolism in the former East Germany.

Since the early 1970s selective screening for inherited metabolic disorders has been performed in larger children's hospitals or metabolic centres of the former East-Germany. As a rule the following methods were employed: initially paper chromatography, drop, dip and spot tests, later on thin-layer chromatography and more recently enzyme analysis, gas chromatography, mass spectrometry and HPLC. Normally urine, blood or leucocytes were investigated. The diagnoses were confirmed in metabolic centres in Greifswald, Berlin or Leipzig or in collaboration with specialized laboratories abroad. About 130,000 subjects from former East Germany as well as from different East European countries were investigated, of which 365 patients were diagnosed and classified into roughly 40 various metabolic diseases. The proportion of positive diagnoses was 1 in 400.

Carrier detection of Hunter syndrome (MPS II) by biochemical and DNA techniques in families at risk.

DNA based and biochemical diagnosis of MPS II was performed on 13 unrelated families using Southern blotting. The 35S-sulphate accumulation in cultured fibroblasts was investigated and the iduronate-2-sulphatase (IDS) activity in the serum determined. Sixteen patients and 36 females at risk were screened for structural aberrations and by RFLP analysis using the intragenic probe pc2S15 and probes VK23B, VK21A, and II-10 for the flanking loci DXS297, DXS296, and DXS466. Structural alterations were found in the DNA of two patients. One of them showed a major deletion including the whole coding sequence of the IDS gene. An aberrant Southern fragment occurred in the HindIII/pc2S15 blot of the other patient suggesting a new HindIII restriction site by point mutation in an IDS gene intron. Twenty-nine females were confirmed as carriers, and for five women the heterozygous state could be excluded. Prenatal diagnosis can be offered to 27 women if requested.

Molecular analysis of patients with Hunter syndrome: implication of a region prone to structural alterations within the IDS gene.

Hunter syndrome or mucopolysaccharidoses type II (MPS-II), is a lysosomal storage disorder caused by a deficiency in the activity of the enzyme iduronate-2-sulphatase (IDS). We have investigated the occurrence of rearrangements and deletions of the IDS gene in a Southern analysis of 46 unrelated MPS-II patients of different ethnic origins using a cDNA clone containing the entire IDS gene as a probe. Structural alterations of the IDS gene were found in DNA from 9 patients two of whom showed large deletions including all coding sequences of the gene. The distal and proximal breakpoint of these deletions were determined by hybridization of markers flanking the IDS gene. Seven of the observed alterations constitute major rearrangements of the gene. Interestingly, six of these rearrangements showed similar or identical patterns by Southern analysis suggestive for a region prone to structural alterations within the IDS gene. We also demonstrate the potential use of the IDS probe for carrier detection in families with a rearranged IDS gene. A contiguous gene deletion syndrome characterized by Hunter syndrome and epilepsy is also discussed.

[Mucopolysaccharidoses. Genetics, clinical pathology, therapeutic regimes]. / Mucopolysaccharidosen. Genetik, klinische Pathologie, Therapieansätze.

In recent years, several clinical and biochemical studies have been published contributing to better understanding of mucopolysaccharide storage diseases. Our purpose, therefore, is, to give an updated survey of this group of lysosomal diseases for diagnostic orientation to the pathologist. The present classification of mucopolysaccharidoses is based on a mixture of clinical symptoms, demonstration of enzyme defects, analysis of urinary excretion of glycosaminoglycans (mucopolysaccharides) and historical eponyms. A broad heterogeneity has been revealed: identical enzyme defects may lead to severe mental and physical deterioration and death during childhood or to mild forms with normal adult height, intelligence, and life expectancy. Conversely, identical phenotypes may result from mutations of different genes. Various types of mucopolysaccharidoses are mostly characterized by quantitative differences of main symptoms (coarse facial features, various skeletal abnormalities, hepatosplenomegaly, corneal clouding, mental retardation, and cardiac failure). Morphologically, storage material can be observed practically in all tissues by light and/or electron microscopy. Until recently, no more than palliative treatment could be offered. In the last decade, bone marrow transplantation has become available and may have beneficial effects in selected cases. The genes of several lysosomal enzymes have been identified, and comprehensive studies to introduce the gene into defective cells are currently undertaken. However, substantial efforts are still necessary until gene transfer will become available for patients with mucopolysaccharidoses.

[Maternal phenylketonuria. Problems in detecting and risk educating identified females]. / Maternale Phenylketonurie. Problematik der Auffindung und Risikoaufklärung betroffener Frauen.

Maternal PKU is an embryo-fetopathy caused by elevated plasmaphenylalanine levels in pregnant women with hyperphenylalaninemia and phenylketonuira. Leading symptoms are microcephaly, mental retardatioin and congenital malformations, especially congenital heart disease. Maternal PKU becomes more important since early treated and normally developed girls with PKU are reaching their reproductive age in increasing numbers. There is a lack of adequate knowledge about the dangers of maternal PKU in at-risk women. Only 43% of these women in the Federal Republic of Germany are located by now and can be informed and instructed. Ways and conditions of tracking are described.

Tryptophan metabolic studies in patients with presenile cataracts.

In 43 patients with presenile cataracts an oral tryptophan loading test with 5 g L-tryptophan was performed and the 24-hour urinary excretion of kynurenine and xanthurenic acid was determined. 5 cases showed pathological deviations and an excretion pattern of tryptophan metabolites via kynurenine, similar as in vitamin B6-dependent xanthurenic aciduria.

[Pathomorphology of mucopolysaccharidoses]. / Pathomorphologie der Mucopolysaccharidosen.

Mucopolysaccharidoses are autosomal recessive or X-linked hereditary lysosomal storage diseases occurring to one in 10,000 to 16,000 births. The definitive diagnosis is based on the biochemical verification of the enzyme defect in cultured fibroblasts of amniotic fluid cells, in amniotic fluid, in chorionic biopsies and by determination of the urinary excretion of glycosaminoglycans. Morphological studies are of utmost importance both for genetic counselling and enlightenment of the pathogenesis. In recent years, numerous reports appeared dealing with morphological changes in different types of mucopolysaccharidoses. Based on own studies in pre- and postnatal cases, the present paper gives an update review on light and electron microscopic peculiarities of the different types and subtypes of mucopolysaccharidoses according to the classification of MCKUSICK and NEUFELD (1983). Lysosomal storage is found in practically all organs. However, there are quantitative and qualitative differences which are responsible for variations in clinical symptomatology. The purpose of this paper is to describe these differences with particular emphasis on changes in various tissues, on the pathogenetic mechanism of the storage as well as on pre- and postnatal morphological diagnostics.

[Diagnosis of lysosomal storage diseases. Pathomorphologic and biochemical possibilities]. / Diagnostik lysosomaler Speicherkrankheiten. Pathomorphologische und biochemische Möglichkeiten.

Optical light and electron microscopy were used in studies into two cases of infantile GM2-gangliosidosis. The results are reported in this paper. The correlation has been evident between histological and ultrastructural findings. Reliable delimitation between two different variants of infantile GM2-gangliosidosis was achieved through biochemical investigation of postmortally cultured skin fibroblasts. A classical form with isolated hexosaminidase-A defect (Tay-Sachs disease) was distinguished from a second variant with complete defect of both isoenzymes of hexosaminidase (Sandhoff's disease). Biochemical investigation of postmortally cultured fibroblasts today has become indispensable to enlargement of autopsy findings from other storage diseases, as well.

[A staged plan for laboratory diagnosis of hereditary metabolic diseases]. / Stufenplan zur Labordiagnostik hereditärer Stoffwechselerkrankungen.

When clinical evidence provides grounds for suspecting inborn errors of metabolism it is urgent to perform the necessary, relevant, specific laboratory investigations in good time and with a view to quality. Normally, the realization depends on individual initiatives and the use of laboratories mainly designed for pediatrics and human genetics. Consequently the results are equally a matter of chance. Nothing in this situation can be changed in principle by using the catalogue of services of the Society for Human Genetics of the GDR. Central administrative provisions are necessary to improve the present unsatisfactory situation. Proposals for regulations, division of responsibility and a graduated programme of parameters are discussed here with a view to establishing uniform procedures.

Prenatal diagnosis of phenylketonuria by haplotype analysis.

Prenatal diagnosis of classic phenylketonuria (PKU) was performed after chorionic villus sampling by means of linked restriction fragment length polymorphisms (RFLPs) using the cDNA probe ph PAH 247 (Kwok et al. (1985) Biochemistry, 24, 556-561). We report in this paper a PKU family who were only informative for RFLP analysis by a combination of two RFLPs on the basis of haplotype determination of the normal and mutant phenylalanine hydroxylase (PAH) alleles. The DNA analysis detected a PKU fetus homozygous for mutant PAH alleles and the mother opted for termination in the 12th week of gestation.

[Distribution of cystinuria subtypes in the Democratic Republic of Germany]. / Zur Verteilung der Subtypen der Zystinurie in der DDR.

The classic cystinuria is a hereditary disorder characterized by a defective transport of cystine and the dibasic amino acids arginine, lysine and ornithine in the epithelial cells of the renale tubule and the gastrointestinal tract. The excretion patterns of cystine and the dibasic amino acids in 24-hour urine samples from heterozygotes can be used to the differentiation between the genetic subtypes. 120 probands in the age range from 3 to 70 years from 22 families with cystinuria were investigated by thin-layer chromatography and by ion exchange chromatography. In patients with cystinuria the genotype I-I has a frequency of 50%. These results and the distribution of the other subtypes are in accordance with published data. From 98 persons investigated in 22 families with cystinuria 14 run the risk to form cystine stones. Therefore, the knowledge of the subtypes is relevant for practice.

Haplotype analysis of classical and mild phenotype of phenylketonuria in the German Democratic Republic.

The restriction fragment length polymorphism (RFLP)-haplotypes have been analysed in 16 families from the northern part of the GDR at risk for classical and mild phenylketonuria (PKU). Ten different RFLP haplotypes associated with the normal and mutant phenylalanine hydroxylase (PAH) alleles were identified. Of the 32 mutant alleles analysed, 29 (90.6%) were associated with haplotypes 1, 2, 3 and 4; 53.1% of the mutant alleles were linked with haplotype 2. The distribution of RFLP haplotypes in 16 patients of clinical different PKU phenotypes (classical and mild) is reported.