Fatal hyperammonaemia due to late-onset ornithine transcarbamylase deficiency.

In this case report we describe a 67-year-old male, admitted to the ICU with pneumonia who unexpectedly developed a fatal coma due to hyperammonaemia. At postmortem the diagnosis late-onset ornithine transcarbamylase deficiency was made. The non-specific clinical presentation, the rapid deterioration and incidentally the fatal outcome all underline the importance of recognition and knowledge of this genetic disorder. Several measures to treat and prevent potentially fatal episodes of hyperammonaemia are available, if only the disorder is recognised in time. In retrospect, several clues to the diagnosis were available in this fatal case, such as voluntary protein avoidance, as well as several male family members who died at a young age of an unknown cause. After his death, two daughters were discovered to be carriers of an OTC gene mutation, as well as his infant grandson. We emphasise the importance of obtaining ammonia levels in all patients with unexplained coma, seizures or cerebral oedema, irrespective of their age, especially in patients in the ICU or in an otherwise catabolic state.

[Male subfertility, modern reproduction techniques and transmission of genetic abnormalities]. / Mannelijke subfertiliteit, moderne voortplantingstechnieken en het doorgeven van genetische afwijkingen.

Somatic cells of males with azoospermia or oligozoospermia (sperm density < 20 million sperm cells/ml) were found to contain increased percentages of chromosomal abnormalities. Subfertile males with a normal somatic karyogram were found to have increased rates of aneuploidy in sperm. This creates risks for the offspring after fertilization with intracytoplasmatic sperm injection (ICSI). Certain gene mutations on the Y chromosome cause severe oligo- or azoospermia and will, in case of successful reproduction with ICSI, be transmitted to male offspring in 100% of the cases. The same holds true, irrespective of sex, of mutations responsible for cystic fibrosis. In non-random groups of ICSI pregnancies, higher proportions of de novo sex-chromosomal abnormalities have been found than expected. In addition, there are increased proportions of paternally inherited structural autosomal anomalies. Extrapolation of the findings is not yet possible, however.

Neurofibromatosis presenting with a cherubism phenotype.

We report on a child who presented clinical manifestations of both neurofibromatosis type 1 (NF1) and cherubism. With genetic testing, we found a mutation in the NF-1 gene, confirming the neurocutaneous disorder. Histology when correlated with radiological evaluation of a mandibular biopsy was consistent with cherubism. This is the first report in the literature of a child with proven neurofibromatosis type 1 and cherubism without extragnathic lesions. This emphasises that cherubism is a clinical phenotype that can be associated with a number of germline mutations involving SH3BP2, PTPN11 and NF1.

Striking facial dysmorphisms and restricted thymic development in a fetus with a 6-megabase deletion of chromosome 14q.

During routine ultrasound screening at 12 weeks 5 days of gestation, a nuchal translucency of 7 mm, an omphalocele, and fetal hydrops were found and prompted chorionic villus sampling at 13 weeks 2 days. Chromosome analysis showed an unbalanced karyotype with an abnormal chromosome 14. The mother was a carrier of a translocation karyotype 46,XX,t(13;14) (q34;q32.2). In the fetus this gave rise to a partial trisomy 13q and partial monosomy 14q (fetal karyotype: 46,XX,der[14]t[13;14][q34;q32.2]). By Array-CGH on DNA extracted from a postmortem skin culture, a duplication of approximately 1.7 Mbp of the distal part of chromosome 13q34 and a deletion of approximately 6.0 Mbp of the distal part of chromosome 14q32.2 was demonstrated. Postmortem findings after termination of pregnancy at 14 weeks 6 days included, among others, a severe hypoplasia of the median part of the maxilla, no recognizable nose, a broad median palatoschisis, nonlobulated lungs, a horseshoe kidney with multicystic dysplasia, and decreased development of cortical cellularity in the thymus. These clinical manifestations and autopsy findings of the fetus are compared with those of previously published cases and the possible involvement in this pathology of the YY1 and JAG2 transcription factors and the BCL11b and SIVA-1 regulators of thymic development is discussed.

Prenatal detection of complex chromosomal aberrations using advanced molecular cytogenetic techniques.

OBJECTIVE: This study aimed to identify a marker chromosome and characterize the short arm of a derivative chromosome 5 in a foetus with the following karyotype: mos 47,XX,del(5)(p?),+i(5)(p10)[50]/48,XX,del(5)(p?),+i(5)(p10),+mar[25]. METHOD: Amniocentesis was performed in the 26th week of pregnancy because of ultrasound abnormalities (polyhydramnion and decreased amount of gastric filling). All classic banding techniques were performed. FISH and microdissection combined with reverse painting were used to reveal the exact origin of the marker and any extra material on the deleted chromosome 5p. The parents decided to continue the pregnancy and we compared the clinical features of the child born in week 34 with data from the literature on trisomy 5p. The possible contribution of trisomy of the centromeric region of chromosome 8 and trisomy 8p23.3-->8pter to this clinical picture was evaluated. RESULTS: GTG banding showed one normal and two aberrant chromosomes 5 [del(5)(p?) and i(5)(p10)] in all the cells examined. Furthermore, a supernumerary marker chromosome was present in approximately 30% of the cells. The marker was CBG positive and positive with the pancentromere probe, but dystamicinA/DAPI negative. It did not contain NOR-positive satellites. FISH proved this marker to be derived from the centromeric region of chromosome 8. MicroFISH disclosed the aberrant chromosome 5 as der(5)t(5;8)(p10;p23.3). The parent's karyotypes were normal. The baby showed the characteristic features of trisomy 5p syndrome. She died at the age of 15 days after cardiorespiratory arrest. CONCLUSION: The karyotype was interpreted as mos 47,XX,add(5)(p10).rev ish der(5)t(5;8)(p10;p23.3),+i(5)(p10) (WCP5+,D5S23+)[50]/48,XX,add(5)(p10).rev ish der(5)t(5;8)(p10;p23.3),+i(5)(p10)(WCP5+,D5S23+),+mar.ish 8(p10q10)(D8Z2+,WCP8-)[25]. Therefore, the baby had complete trisomy 5p, with trisomy of the distal part of 8p and of the centromeric region of chromosome 8. The clinical significance of de novo marker chromosomes is a major problem in prenatal counselling. Molecular cytogenetic tools such as FISH and microFISH are indispensable for characterizing markers and determining the breakpoints more precisely in deleted chromosomes.

Maternal uniparental disomy for chromosome 22 in a child with generalized mosaicism for trisomy 22.

We report on a case of generalized mosaicism for trisomy 22. At chorionic villus sampling (CVS) in the 37th week of pregnancy, a 47,XX,+22 karyotype was detected in all cells. The indication for CVS was severe unexplained symmetrical intrauterine growth retardation (IUGR) and a ventricular septal defect (VSD) was noted. In cultured cells from amniotic fluid taken simultaneously, only two out of ten clones were trisomic. At term, a growth-retarded girl with mild dysmorphic features was born. Lymphocytes showed a normal 46,XX[50] karyotype; both chromosomes 22 were maternal in origin (maternal uniparental disomy). Investigation of the placenta post-delivery using fluorescence in situ hybridization showed a low presence of trisomy 22 cells in only one out of 14 biopsies. In cultured fibroblasts of skin tissue, a mosaic 47,XX,+22[7]/46,XX[25] was observed. Clinical follow-up is given up to 19 months.

Phenylketonuria in The Netherlands: 93% of the mutations are detected by single-strand conformation analysis.

Single-strand conformational analysis was used to screen for genetic defects in all thirteen exons of the phenylalanine hydroxylase gene (PAH) in phenylketonuria and hyperphenylalaninemia patients in the Netherlands. Exons that showed a bandshift were sequenced directly. In this way, we were able to identify 93% of the PAH mutations in a panel of 34 patients. Twenty-one different mutations were found: 4 of these gene aberrations are novel.