[Germline mosaicism in a family with Duchenne muscular dystrophy]

In families with Duchenne/Becker muscular dystrophy, DNA analysis allows direct detection of the sex-linked dystrophy gene mutation. The detection of two alleles (heterozygous) in the region of a deletion in an affected son, excludes the mother having the same deletion. However, it is known that in isolated cases of this disease there is a risk of mosaicism, resulting in genetically different cell lines in the same or different tissues. Because of this consideration, in a subsequent pregnancy, prenatal diagnosis was performed on the mother, who was previously excluded from carrying the deletion based on DNA analysis of blood leukocytes. The examination showed the sex of the foetus to be male, and notably, a deletion identical to that in the ill boy was detected. This indicates that the patient has a germ cell deletion (germline mosaicism).

Adult schizophrenic-like variant of adrenoleukodystrophy

A 35-year-old man died after 30 months following the onset of the disease. There was a history of changes in his mental condition, including disturbances of behavior as well as the evidence of progressing dementia. The patient revealed gait disturbances and finally became bed ridden. Bizarre behavior and changes of mood with concurrent growing irritability which predominated during the course of disease, may explain the initial diagnosis of schizophrenia. Then cerebellar and spastic movement disorders leading to paraparesis and sphincters disturbances developed. Clinical symptoms of adrenal failure were not found apart from episodes of arterial pressure fall. After two years a magnetic resonance imaging (MRI) revealed an extensive diffuse demyelinative process in white matter of cerebral and cerebellar hemispheres. Activity of lysosomal enzymes was normal. A general autopsy revealed atrophy of adrenal cortex and the presence of ballooned cells with striated cytoplasm in the reticular and fasciculate zones. Neuropathological examination revealed an extensive demyelination of white matter in cerebral and cerebellar hemispheres and of the long paths of the brain stem, corresponding to changes in MRI examination. Within demyelination areas damage of axons and diffuse cellular and fibrous gliosis were found as well as perivascular lymphocytic infiltrations with the presence of strong PAS (+) and Sudan (+) macrophages. Immunocytochemical reactions with HAM-56 and RCA1 in macrophages were positive. Electron microscopy examination revealed lamellar inclusions in cytoplasm of macrophages. Similar structures were present in the lysosomes of astrocytes. Morphological examination of adrenal glands as well as morphological and ultrastructural study of the brain allowed us to diagnose the cerebral form of adrenoleukodystrophy (ALD). Topography and character of the brain changes seems to be in keeping with a rare schizophrenic-like variant of ALD with progressive dementia. Abnormal plasma profile and increased VLCFA concentration in the patient's 13-year-old daughter confirm the ALD diagnosis.

Intrafamilial variability of the ocular phenotype in a Polish family with a missense mutation (A63D) in the Norrie disease gene

PURPOSE

To describe the phenotypic variability in a Polish Norrie disease (ND) family associated with the missense mutation A63D.

METHODS

A patient with spared vision from a Polish ND family underwent detailed ophthalmological examinations including slit-lamp biomicroscopy, ultrasound (USG), angiography, Goldmann kinetic visual field, and electroretinography (ERG). Mutation screening was carried out using the single-strand conformation polymorphism (SSCP) technique and subsequent DNA sequencing of the coding part of the ND gene.

RESULTS

A mutation was detected (exon 3, A63D) in a large Polish family with 12 affected males, all but one presenting with classical ND symptoms. In one male, partially preserved vision was observed up to 40 years of age (distance acuity of the right eye 1/50 and left eye 2/50). Slit-lamp examination revealed remnants of a persistent primary vitreous and hyaloid artery. Upon angiography, the retina was vascularized within the posterior pole but not in the periphery. The ERG revealed pathological changes characteristic for chorioretinal degenerations.

CONCLUSION

Within one family, individuals with identical sequence alterations in the ND gene can show remarkable phenotypic variability of the ocular symptoms. These findings indicate the involvement of additional factors (epigenetic or genetic) in ocular pathogenesis of ND.

[Open neural tube defects in prenatal diagnosis]

The problem of open neural tube defects (ontd) is discussed in the light of results of prenatal tests performed in the district of Warsaw. These results seem to bear some epidemiological significance allowing estimation of approximate frequency of ontd as well as recurrence risk for the purpose of genetic counselling. Prenatal diagnosis of ontd is very important for individual families--particularly those with increased risk. However, in view of very small number of prenatal tests and the fact that maternal serum screening and ultrasonografic screening are practically not available the demographic impact of prenatal diagnosis in Poland on the frequency of ontd (and other genetic diseases) in Poland must be negligible.

Two distinct deletions in the IDS gene and the gene W: a novel type of mutation associated with the Hunter syndrome

A novel mutation has been identified in a patient with the Hunter syndrome (mucopolysaccharidosis type II), in whom the disorder is associated with two distinct deletions separated by 30 kb. The deletions were characterized by Southern blot and PCR analyses, and the nucleotide sequences at both junctions were determined. The first deletion, corresponding to a loss of 3152 bp of DNA, included exons 5 and 6 of the iduronate-2-sulfatase (IDS) gene. The second deletion was 3603 bp long and included exons 3 and 4 of gene W, which is located in the DXS466 locus telomeric of the IDS gene. Both deletions are the result of nonhomologous (illegitimate) recombination events between short direct repeats at the deletion breakpoints. An interesting finding was the presence of the heptamer sequence 5'-TACTCTA-3' present at both deletion junctions, suggesting that this motif might be a hot spot for recombination. We propose that the double deletion is the result of homology-associated nonhomologous recombinations caused by the presence of large duplicated regions in Xq27.3-q28.

Erythrocyte glucose-6-phosphate dehydrogenase deficiency in Poland--a study on the 563 and 1311 mutations of the G6PD gene

Studies on the mutation 563T and silent mutation 1311T of the glucose-6-phosphate dehydrogenase (G6PD) gene in Poland were performed in 26 families affected with G6PD deficiency classified-according to WHO-as group 2 G6PD deficiency. Both mutations were found in 19 families, including 17 of Polish origin. Mutation 563T alone was found in 1 Greek female. The frequency of the silent mutation 1311T in Polish unaffected controls was 0.10. It is postulated that at least parts of the Polish (or Middle-Eastern European) and Mediterranean populations are of a common origin.

Asymptomatic and late-onset ornithine transcarbamylase (OTC) deficiency in males of a five-generation family, caused by an A208T mutation

In a large five-generation Polish family, late-onset ornithine transcarbamylase (OTC) deficiency in males segregated with the missense mutation Ala208Thr (A208T), and all heterozygous females were asymptomatic. No other mutations were found in the coding sequences and intron-exon boundaries of the OTC gene. Surprisingly, the mutation originated from the great-grandfather of the index patient who died at age 59 of liver carcinoma. He never had dietary restrictions or hyperammonemic spells throughout life and appears to be the oldest male reported with OTC deficiency. The index patient had a severe OTC deficiency (3% of normal). Eight males died suddenly at ages 4 months to 23 years (average 14 years) after a foudroyant episode triggered by a common infection. The patients remained undiagnosed for 28 years because a metabolic defect was not considered to be the cause of the acute episodes. Recognition of the familial pattern of inheritance was initially unnoticed since the patients were admitted to eight different hospitals. DNA analysis predicted that two 'healthy' boys also had OTC deficiency, which was confirmed by abnormal results of allopurinol challenge tests. Initial suspicion of OTC deficiency in such families is complicated, since symptoms can develop at any age, or even remain absent. This obscures the typical pattern of X-linked inheritance in small families.

[Detection of dystrophin gene mutation carrier state]

RFLP polymorphism and the sequence of repeated CA were analysed by means of polymerase chain reaction in 62 families in which cases of DMD/BMD had occurred. The established carriers were suggested to undergo prenatal examinations for avoiding giving birth to a child with Duchenne or Becker type of muscular dystrophy.

[The alpha-fetoprotein level analysis in open neural tube defects and chromosomal aberrations in the fetus]

During the last 12 years 4258 amniocenteses were performed between the 12th and 20th week of gestation (including 323 early amniocenteses carried out before 15th week). In every case, cytogenetical examination was performed and concentration of AFP was determined. In cases with elevated AFP level electrophoresis of AchE izoenzymes was performed. The results of the tests enabled us to calculate laboratory standard values of AFP in the amniotic fluid for 12th to 20th weeks of gestation. In 22 of 44 pregnancies with Down's syndrome the value of AFP concentration was below the 25th percentile of the laboratory normal value. In 5 of 10 pregnancies with Edward's syndrome AFP level exceeded significantly the 75th percentile of the laboratory norm. In two cases it was due to coexisting spina bifida and in one case due to omphalocele. In 28 amniotic fluid samples AFP concentration exceeded normal level and electrophoresis of AchE revealed additional band. In 26 cases increased values of AFP were due to open neural tube defect in the fetus: 13 cases of anencephaly and 13 cases of spina bifida; in the remaining two other cases omphalocele was found.

An unusual pedigree with microcornea-cataract syndrome

A pedigree with 14 patients affected with microcornea-cataract (MC) syndrome is described. MC syndrome is very rare and this pedigree is probably the sixth to be reported. Transmission is most likely autosomal dominant, but the unusual feature of the present family is the fact that the proportion of affected members is so high that one is tempted to suspect preferential transmission of the chromosome carrying the MC gene.

Prenatal diagnosis of Sanfilippo disease type C using a simple fluorometric enzyme assay

A new fluorogenic substrate, 4-methylumbelliferyl beta-D-glucosaminide, was used for the assay of acetyl CoA:glucosaminide N-acetyltransferase in chorionic villi, cultured villus cells, and amniocytes. Optimal conditions for the assay and the ranges of enzyme activity were established for the various types of fetal cells. This simple fluorometric assay provides a reliable method for early prenatal diagnosis of Sanfilippo disease type C which is more convenient than current methods using radiolabelled substrates. The method was applied to amniotic fluid cells and fetal fibroblasts from an at-risk pregnancy in which an affected fetus was diagnosed by two-dimensional electrophoresis of glycosaminoglycans in the amniotic fluid.

[Deletions within the gene of dystrophin in Duchenne and Becker muscular dystrophy]

DNA was isolated and analysed in 96 patients with Duchenne or Becker muscular dystrophy (DMD, BMD); 9 of them were affected with BMD. Delections were found in 60 Patients (62.5%) using six cDNA probes. In some cases the PCR technique was also applied. In patients with BMD all deletions but one were in frame and involved exons 45-54. On the contrary, most deletions in DMD were out of frame and varied in their location. In five families prenatal diagnosis was carried out.

Emery-Dreifuss muscular dystrophy: linkage to markers in distal Xq28

Emery-Dreifuss muscular dystrophy (EMD) is characterised by (1) early contractures of the Achilles tendons, elbows, and postcervical muscles, (2) slowly progressive muscle wasting and weakness with a predominantly humeroperoneal distribution in the early stages, and (3) cardiomyopathy with conduction defects and risk of sudden death. Inheritance is usually X linked recessive but can be autosomal dominant. Family linkage studies have mapped X linked EMD to the distal long arm of the X chromosome but precise genetic localisation has been hampered by the rarity of this condition. We report three new families with X linked Emery-Dreifuss muscular dystrophy studied with DNA markers from Xq27-qter and three previously published families typed for additional markers. No recombination was observed with the red/green cone pigment locus, RGCP (lod score, Z = 2.46), the factor VIII coagulant gene locus, F8C (Z = 6.39), or with DXS115 (Z = 4.94). Two recombinants were observed which mapped EMD distal to DXS15 (DX13) and DXS52 (St14) respectively. Multipoint linkage analysis gave odds exceeding 200:1 for EMD being distal to these markers. A multipoint analysis incorporating published data gave the map cen-DXS304-9cM-DXS15-3cM-DXS52-2 cM-(RGCP,EMD)-3cM-F8C-2cM-DXS115 with odds of 120:1 in favour of a location for EMD between DXS52 and F8C as compared to the next best position distal to F8C.

[A case of progressive multisystem damage of the central nervous system with suspected olivopontocerebellar atrophy type I]

A case of progressive multisystem damage to the central nervous system was observed in a patient aged 36 years. On the ground of family history, disease course, clinical findings and results of laboratory investigations type I of olivo-ponto-cerebellar atrophy according to McKusick's classification was suspected.

[Function and diseases of peroxisomes]

The properties and metabolic functions of peroxisomes are discussed. Classification and clinical symptoms of various diseases resulting from deficiencies of those organellae are presented. Most of the diseases involve the nervous system. The detection and determination of long-chain fatty acids (containing over 26 carbon atoms) is the principal diagnostic method in peroxisomal diseases.

[A case of mannosidosis type II]

A case of L-mannosidosis, a recessively inherited thesaurosis, is reported. Since birth the patient had evidence of immunodeficiency. The neurological manifestations developed during adolescence with slurred and slow speech with scanning, muscle flaccidity, sings of Trömner and Jacobson, intentional tremor, equilibrium disturbances. After many laboratory investigations the tests for inherited metabolic disorders made the correct diagnosis possible.