Genetic counselling and prenatal diagnosis of osteogenesis imperfecta caused by paternal mosaicism

In a family with recurrent osteogenesis imperfecta (OI) caused by paternal mosaicism, prenatal diagnosis was made using restriction enzyme analysis for a mutation in COL1A2. Parental mosaicism is important to consider in genetic counselling for OI. Prenatal diagnosis of OI is available currently by means of collagen or gene analyses in the first trimester or by ultrasonography in the second trimester.

[A follow-up study of carriers of cystic fibrosis]

The aim of the present study was to assess the long-term impact of carrier screening for cystic fibrosis. The impact of being identified as a carrier for cystic fibrosis was assessed through three questionnaires measuring the emotional responses, changes in reproductive attitudes and decisions, retention of the result, and sharing of the information about the result with relatives. The questionnaires were sent to 160 women identified as carriers between 1990 and 1992 and to 200 randomly selected women with a negative result. Carriers became surprised, anxious and worried upon receipt of their result. However, this response disappeared once the partners had been tested and found negative. No sign of residual anxiety was found among carriers who answered the third questionnaire in November 1994. Carriers freely shared the information about their result with relatives, friends, and general practitioners. Few carriers changed their reproductive plans or attitudes to abortion of a foetus with CF due to the result. No decline in fertility or change in reproductive pattern were observed among carriers after testing. The imperfect sensitivity of the carrier test caused some misunderstanding in the retention of the result. This may reflect inadequacies in the information and counselling. Psychological factors are also believed to contribute to the misunderstanding of the result. The information should be improved to avoid false reassurance.

Psychological and social impact of carrier screening for cystic fibrosis among pregnant woman--a pilot study

The aim of the current study was to assess the psychological and social impact of delta F508 carrier screening for cystic fibrosis among pregnant women. The impact of carrier screening was assessed in terms of anxiety, perception of health, reproductive decisions, retention of results, and sharing of information with relatives by two self-administered questionnaires sent to 160 women with a positive and 200 women with a negative test result. While no attempt was made to make women accept or decline testing, 22-28% of those tested found it difficult to reject the test when offered. Women with a positive test result became more anxious than did women with a negative result. However, their perception of future health did not change. Most carriers shared the information about their result with relatives and friends. Carriers had the best retention of pretest information and test result, although a third of the carriers believed that they could not have a child with cystic fibrosis when the partner's test for delta F508 and five other mutations were negative. Most women with a negative test result did not remember their result correctly a year after testing. Few women with a positive result changed their reproductive plans because of the result of the test.

Mutation spectrum in patients with Wiskott-Aldrich syndrome and X-linked thrombocytopenia: identification of twelve different mutations in the WASP gene

Twelve different mutations in the WASP gene were found in twelve unrelated families with Wiskott-Aldrich syndrome (WAS) or X-linked thrombocytopenia (XLT). Four frameshift, one splice, one nonsense mutation, and one 18-base-pair deletion were detected in seven patients with WAS. Only missense mutations were found in five patients diagnosed as having XLT. One of the nucleotide substitutions in exon 2 (codon 86) results in an Arg to Cys replacement. Two other nucleotide substitutions in this codon, R86L and R86H, have been reported previously, both giving rise to typical WAS symptoms, indicating a mutational hot spot in this codon. The finding of mutations in the WASP gene in both WAS and XLT gives further evidence of these syndromes being allelic. The relatively small size of the WASP gene facilitates the detection of mutations and a reliable diagnosis of both carriers and affected fetuses in families with WAS or XLT.

Deletion of a Gly-Pro-Pro repeat in the pro alpha2(I) chain of procollagen I in a family with dominant osteogenesis imperfecta type IV

We have investigated one member of a family with dominant osteogenesis imperfecta type IV through three generations. In protein-chemical studies of cultured fibroblasts derived from the proband, collagen I was overmodified, with normal processing of procollagen I, normal thermal stability, and a cyanogen bromide peptide map that suggested a C-terminal location of the structural abnormality in the collagen triple helix. Sequencing of the gene encoding the alpha2(I) chain of collagen I (COL1A2) indicated a nine base-pair deletion of nucleotides 3418-3426. When a polymerase chain reaction product containing the nucleotides in question was electrophoresed in a 12% polyacrylamide gel, two bands with a difference in size of nine base pairs could be shown. Sequencing of the molecular weight band confirmed the deletion of the nine base pairs involving codons 1003-1006 of COL1A2. The deletion introduced a SfiI restriction site that was used for confirmation of the deletion in genomic DNA from the proband. The deletion resulted in the removal of three amino acids (Gly-Pro-Pro), but this did not disrupt the Gly-X-Y sequence of the collagen triple helix, as is often the case in the more common glycine substitutions. We discuss the ways in which this deletion could result in osteogenesis imperfecta.

First-trimester prenatal diagnosis of Crouzon syndrome

Crouzon syndrome, one of the best known of many craniofacial syndromes, is an autosomal dominant disorder characterized by craniosynostosis, prominent eyes, and midfacial hypoplasia due to abnormal development and premature fusion of the skull. Recently mutations in the fibroblast growth factor receptor 2 gene (FGFR2) were found to cause Crouzon. We have identified the recurrent mutation C342Y in two unrelated patients with Crouzon syndrome. One patient (A) belongs to a family in which Crouzon could be followed in three generations, while the other patient (B) represents a sporadic case. The identification of the disease-causing mutation allowed first-trimester prenatal diagnosis as requested by both patients in their subsequent pregnancies. A chorionic villus biopsy was performed in the 11th gestational week of patient A's pregnancy. DNA isolated from the biopsy revealed a fetus heterozygous for the C342Y mutation, i.e., having Crouzon syndrome. The pregnancy was terminated and the molecular diagnosis was confirmed later by analysis of fetal and placental tissue. Patient B had a missed abortion before the scheduled chorionic villus biopsy was performed. Mutation analysis of the aborted fetal tissue did not show the C342Y mutation.

Gly802Asp substitution in the pro alpha 2(I) collagen chain in a family with recurrent osteogenesis imperfecta due to paternal mosaicism

A proband with osteogenesis imperfecta (OI) type III/IV was born to clinically normal parents, who subsequently had two pregnancies terminated because of OI in the fetuses. Cultured fibroblasts from the proband, one fetus and the father produced abnormal collagen I. Cyanogen bromide mapping localised the defect to the region of the alpha 1(I)CB7 peptide. Sequencing revealed a G to A transition at nucleotide 2814 in COL1A2 in the proband, the fetus, and the father, which resulted in a Gly802Asp substitution in the pro alpha 2(I) collagen chain. About 25% of the paternal alleles from fibroblasts and leucocytes and 40% of paternal alleles from spermatocytes carried the mutation consistent with somatic and germinal mosaicism. For genetic counselling, parental mosaicism must be considered in all sporadic cases of OI.

Psychological impact of carrier screening for cystic fibrosis among pregnant women

The aim of the present study was to assess the impact of being identified carrier of cystic fibrosis. The impact was assessed in terms of retention of the result, sharing of the information about the result with relatives, non-relatives and GPs, changes in reproductive plans, and regrets about having been tested Three unsupervised questionnaires were sent to 160 women identified as carriers between 1990 and 1992 in June 1992, October 1993, and November 1994. Carriers freely shared the information about their result with relatives, friends, and GPs. The inconclusiveness of the test gave rise to some confusion. This may reflect inadequacies in the information and counselling given to carriers, but psychological factors are also believed to be responsible. Thus, false reassurance may be a problem in a carrier screening with a test that detect only a proportion of carriers. Few carriers considered changing their reproductive plans due to the result of the test. A few women identified as carrier regretted having had the test.

Abnormal synthesis of dolichol-linked oligosaccharides in carbohydrate-deficient glycoprotein syndrome

Carbohydrate-deficient glycoprotein syndrome (CDGS) is a rare metabolic disorder presenting in infancy with severe neurologic involvement and variable multisystemic abnormalities. Diagnosis relies upon the detection of abnormal serum glycoprotein isoforms on isoelectric focusing (IEF) gels. Carbohydrate structural analyses were performed on the N-linked oligosaccharides of serum alpha 1-antitrypsin (alpha-1AT) from two Danish children with classical type I CDGS. Following preparative gel electrophoresis of alpha-1AT isoforms, oligosaccharide charge and monosaccharide composition analyses revealed increased glycosylation heterogeneity in CDGS compared with normal alpha-1AT. CDGS alpha-1AT isoforms bore N-glycans co-migrating with monosialylated standards, while normal alpha-1AT oligosaccharides co-migrated with both mono- and disialylated standards. While the monosaccharide contents of normal alpha-1AT isoforms were relatively uniform, those of CDGS alpha-1AT isoforms varied widely, and many were relatively mannose enriched. The mannose-rich oligosaccharides of CDGS alpha-1AT were not typical oligomannose structures since they were not released by endo-beta-N-acetylglucosaminidase H (endo H) digestion. Metabolic labelling of CDGS fibroblasts with [3H]mannose showed lower than normal intracellular total mannose, free mannose and phosphorylated mannose species, as well as diminished [3H]mannose incorporation into dolichol-linked and protein-linked oligosaccharides. In addition, the glycans liberated from CDGS dolichol-linked oligosaccharides were significantly truncated compared with those from normal fibroblasts. These data suggest that our type I CDGS patients produce abnormal N-linked oligosaccharides due to impaired biosynthesis of dolichol-oligosaccharide precursors.

A novel variant of lysosomal acid lipase (Leu336-->Pro) associated with acid lipase deficiency and cholesterol ester storage disease

Cholesterol ester storage disease (CESD) is associated with premature atherosclerosis, hepatomegaly, elevated LDL cholesterol levels, and in most cases, low HDL cholesterol levels. Previous studies have shown a G-->A mutation at the 3' splice junction of exon 8 (E8SJM) of the gene encoding lysosomal acid lipase (LAL) in two kindreds with CESD. In a Canadian-Norwegian kindred with this disease, we show this mutation in conjunction with an as yet unknown T-->C transition in exon 10 predicting a Leu336-->Pro (L336P) replacement and an A-->C transversion in exon 2 predicting a T-6P replacement in the prepeptide. Identification of the L336P rather than the T-6P replacement as the second defect underlying CESD in our patient is deduced from three lines of evidence. First, the E8SJM allele is located in cis with the mutation predicting the T-6P-encoding allele but in trans with the L336P-encoding allele; second, the L336P but not the T-6P replacement cosegregates with low LAL activity in the family; third, the T-6P replacement was found in 6 of 28 alleles from subjects with normal lysosomal acid lipase activity, suggesting that this variant represents a frequent nonfunctional polymorphism. Since the residual LAL activity is higher and the clinical phenotype based on plasma lipid values and severity of hepatosplenomegaly is milder in this case than in a previously studied case who was homozygous for the E8SJM allele, we conclude that the L336P variant appears to be associated with a phenotypically mild form of CESD.

Cerebellar hypoplasia in children with the carbohydrate-deficient glycoprotein syndrome

We describe seven children with the carbohydrate-deficient glycoprotein syndrome, an autosomal recessive inborn error of protein glycosylation characterised by failure to thrive, neurological dysfunction and a unique pattern of physical abnormalities. Neuro-radiological investigations revealed cerebellar hypoplasia in all seven children. Two children also developed supratentorial atrophy following episodes of neurological deterioration.

Severe insulin-resistant diabetes mellitus in patients with congenital muscle fiber type disproportion myopathy

Congenital muscle fiber type disproportion myopathy (CFTDM) is a chronic, nonprogressive muscle disorder characterized by universal muscle hypotrophy and growth retardation. Histomorphometric examination of muscle shows a preponderance of smaller than normal type 1 fibers and overall fiber size heterogeneity. Concomitant endocrine dysfunctions have not been described. We report the findings of altered insulin secretion and insulin action in two brothers affected with CFTDM and glucose intolerance as well as in their nonconsanguineous glucose-tolerant parents. Results are compared with those of six normoglycemic control subjects. All study participants underwent an oral glucose tolerance test to estimate insulin secretion. The oldest boy and his parents volunteered for studies of whole-body insulin sensitivity consisting of a 4-h euglycemic hyperinsulinemic clamp in combination with indirect calorimetry. Insulin receptor function and glycogen synthase (GS) activity and expression were examined in biopsies of vastus lateralis muscle. Despite a 45-90-fold increase in both fasting and postprandial serum insulin levels, both CFTDM patients had diabetes mellitus. Clamp studies revealed that the oldest boy had severe insulin resistance of both liver and peripheral tissues. The impaired insulin-stimulated glucose disposal to peripheral tissues was primarily due to reduced nonoxidative glucose metabolism. These changes were paralleled by reduced basal values of muscle GS total activity, allosterical activation of GS by glucose-6-phosphate, GS protein, and GS mRNA. The father expressed a lesser degree of insulin resistance, and studies of muscle insulin receptor function showed a severe impairment of receptor kinase activity. In conclusion, CFTDM is a novel form of severe hyperinsulinemia and insulin resistance. Whether insulin resistance is causally related to the muscle disorder awaits to be clarified.

Linkage of a locus for carbohydrate-deficient glycoprotein syndrome type I (CDG1) to chromosome 16p, and linkage disequilibrium to microsatellite marker D16S406

Carbohydrate-deficient glycoprotein syndrome type I is a multisystem disease with early severe nervous system involvement. The disease, which is inherited as an autosomal recessive trait, is biochemically characterized by complex defects in the terminal carbohydrate residues of a number of serum glycoproteins. This can be most readily detected in transferrin. A whole genome scan was initiated in order to localize the gene (CDG1) with linkage techniques. We analyzed individuals from 25 CDG1 pedigrees with several highly polymorphic microsatellite markers and after exclusion of about 30% of the genome linkage was detected with markers located in chromosome region 16p. The lod score (Zmax) was above 8 (theta max = 0.00) for several markers in this region. In order to further localize the CDG1 gene, recombination and linkage disequilibrium analyses were performed. Recombination events in some pedigrees indicated that the CDG1 gene is located in a 13 cM interval between microsatellite markers D16S406 and D16S500. Furthermore, allelic association was shown for marker D16S406 indicating that the CDG1 gene is located close to this. No heterogeneity could be detected in the European family material tested by us. The positions of cytogenetically localized flanking markers suggest that the location of the CDG1 gene is in chromosome region 16p13.3-p13.12.

[Screening for carriers of cystic fibrosis. Result of a pilot study among pregnant women]

Total prevention of cystic fibrosis (CF) is possible if all carrier women are found before pregnancy or early enough during pregnancy so that prenatal diagnosis can be offered. The delta 508 allele constitutes almost 90% of the mutations causing CF in the Danish population. We have examined 6599 pregnant women and found 172 carriers of delta F508. Partners of carrier women were examined for delta F508 and five other mutations. Three couples at risk and one foetus with CF were identified. Giving information to couples before and after testing is time consuming. A comprehensive questionnaire was sent to 200 non-carriers and all 172 carriers (response rate 72%). It can be concluded that the project has been very well accepted. However, the majority of carriers were shocked or very worried when they had the test result. Based on this pilot study we recommend nationwide screening for delta F508 early in pregnancy.

[Neurofibromatosis type 1 in children]

We describe the clinical findings in 75 children with neurofibromatosis type 1 (NF-1, von Recklinghausen disease) diagnosed by the National Institute of Health criteria. The children were on average three years old at the time of their diagnosis. In 12 children complications of NF-1 were noted before diagnosis of their underlying condition, and half of the children had a serious complication, including intracranial tumour, optic glioma, scoliosis, pseudarthrosis tibiae, or mental handicap. Most complications of NF-1 occur before the age of ten. Therefore, and because of its severity and multifaceted presentation, children with NF-1 might benefit from follow-up in a multidisciplinary, specialized clinic.

[Screening of school children for familial hypercholesterolemia]

A total of 3025 families with school children aged six to eight years were offered pilot screening for familial hypercholesterolaemia by measurement of the concentration of apolipoproteins A-1 and B in the children's capillary blood and by analysis of their family histories of early ischaemic heart disease. The concentrations of the apolipoproteins were determined by double rocket immunoelectrophoresis of an eluate of blood spotted on filter paper. Results were available from 2085 children. Because their B:A-1 ratio was above the 97.5 centile and their concentration of B was above the 99th centile, 54 children (2.6%) were selected to have their apolipoprotein concentrations reassessed. The 17 children (0.8%) whose values were persistently above the chosen cut-off points, and all of their available first and second degree relatives, had fasting determinations of serum lipid concentrations carried out. Raised serum concentrations of low density lipoprotein cholesterol and an autosomal dominant pattern of hypercholesterolaemia were found in respectively 12 children and 10 families, suggesting a higher incidence of familial hypercholesterolaemia than the reported 1:500. Further investigations among family members disclosed hypercholesterolaemia in 29 relatives. A family history of early ischaemic heart disease was elicited by questionnaire, and was positive in only five of the 12 school children with hypercholesterolaemia. We conclude that analysis of apolipoproteins from capillary blood spotted on filter paper is suitable for screening for familial hypercholesterolaemia, and that this method is more efficient than screening based on family history.

Cholesterol-lowering diets may increase the food costs for Danish children. A cross-sectional study of food costs for Danish children with and without familial hypercholesterolaemia

Food costs for 30 children under dietary treatment for familial hypercholesterolaemia were compared with those of 105 other Danish children. The daily intake of macronutrients and the daily cost of the diet for each child were calculated from dietary intakes and average prices of 365 different food items. The mean +/- SE percentages of energy (E%) from fat in the diet of children with and without known familial hypercholesterolaemia were 23.6 +/- 0.8 E+ and 34.5 +/- 0.5 E%, respectively (P < 0.001). The dietary costs per MJ in these two groups were 3.79 +/- 0.12 Danish crowns (DKr) and 3.34 +/- 0.05 DKr (P < 0.001), taking into account food wastage due to preparation and cooking. The cost per unit of energy increased with decreasing fat energy percentage of the diet for all children as one group (r = -0.37, P < 0.001), as well as for the group of children without familial hypercholesterolaemia (r = -0.35, P < 0.001). Stepwise multiple regression analysis showed that the differences in cost per MJ between the groups could be explained primarily by differences in percentage of energy from fat. We conclude that a reduction of dietary fat from 35 E% to 25 E% may increase food costs by 10-20% for Danish children.

Compromise of the spinal canal in Proteus syndrome

We report on 2 children with spinal stenosis and neurologic sequelae. They illustrate the 2 ways in which spinal compromise may develop in Proteus syndrome--vertebral anomalies or tumor infiltration. In one patient, spinal stenosis resulted from an angular kyphoscoliosis. In the other, cord compression resulted from infiltration of a paraspinal, intrathoracic angiolipoma.

Comparative three-dimensional analysis of CT-scans of the calvaria and cranial base in Apert and Crouzon syndromes

The purpose of this study is to describe and analyze Apert and Crouzon skulls from three-dimensional (3-D) reconstructions of CT-scans. 12 Apert patients and 19 with Crouzon syndrome were included in the study. The age range was 0 to 23 years. All CT-scannings were carried out according to the same protocol with a slice thickness of 2 or 4 mm and 3-D reconstructions of the craniofacial region included midsagittal and horizontal cuts. A number of qualitative characteristics of the calvaria and cranial base were recorded and the cranial base angle was measured on the 3-D models. Our results showed that Apert and Crouzon syndromes are very different in cranial development and their dysmorphology is highly age dependent. We suggest that cartilage abnormalities, especially in the anterior cranial base, play a primary role in cranial development in the Apert syndrome from very early intrauterine life. Several cranial anomalies observed postnatally, however, are caused by the resultant dysmorphic and compensatory growth and are probably compounded by early cranial deformation. The primary abnormality in Crouzon syndrome appears to be premature fusion of sutures and synchondroses. Based on the findings at birth and early infancy it would seem that such fusions occur relatively late in fetal life. The adult cranial form in Crouzon's patients is explainable by resultant dysmorphic and compensatory growth changes. Very early release of the coronal suture areas with advancement of the frontal bone is advocated in both syndromes but for somewhat different reasons.(ABSTRACT TRUNCATED AT 250 WORDS)

[Liver transplantation in Denmark. First-year experiences]

During the first 12 months of the Danish Liver Transplantation program, which began in October 1990, 21 transplantations were performed in 11 women, six men and three children. One patient required a retransplant. Fourteen operations were performed electively and six patients were transplanted for acute and subacute fulminant liver failure and coma, two patients had reduced size livers because of large donor liver. There were no peroperative deaths. One of the elective patients died after three weeks from multiorgan failure and sepsis. Two of the emergency patients died after 20 and 22 days. One from graft dysfunction due to stenosis of the celiac trunk and the other of exudative pericarditis. One patient died from chronic rejection and CMV-infection after seven months. Complications were relatively few and acute rejection occurred in 40% of the patients. Fifteen patients are discharged with normal liver function and 11 of these were back at work, school or previous functions in the home. It is concluded that these results are comparable to the best results from other centres but that 21 transplants in 12 months must be a minimum activity.

Postmortem findings and prenatal diagnosis of Zellweger syndrome. Case report

The postmortem findings of siderosis, renal cortical cysts, pachygyria, cortical heterotopia of the brain and cerebellar hypoplasia in a seven-week-old infant with craniofacial dysmorphism and hypotonia prompted the diagnosis of Zellweger syndrome. This was confirmed by analysis of very-long-chain fatty acids in blood spots from filter paper, collected in the neonatal period, and allowed first trimester diagnosis in the subsequent pregnancies.