Mutations of the apolipoprotein A5 gene with inherited hypertriglyceridaemia: review of the current literature.

Apoliporotein A5 (APOA5), a member of the apolipoprotein family, plays a key regulatory role in triglyceride (TG) metabolism. Even though the exact biochemical background of its mechanism is not yet fully understood, diseases associated with this particular gene highlighted its key role in the metabolism of triglycerides in humans. Naturally occurring functional variants of the gene and their natural major haplotypes are known to associate with moderately elevated triglyceride levels, and are also known to confer risk or protection for major polygenic diseases, like coronary heart disease, stroke, or metabolic syndrome. On the other hand, case reports and even robust resequencing studies verified APOA5 mutations as underlying genetic defects behind extreme hypertriglyceridemic phenotype. Soon after the recognition of the first cases, there were indications which suggest the existence of less frequent genetic variants which, in combination with the common allelic variants of the gene, can define haplotypes that are associated with substantial triglyceride level increase. In addition, it became evident, that there are rare mutations of the APOA5 gene which can be associated with specific complex phenotypes and different types of hyperlipoproteinemia, which includes extremely high triglyceride levels with multiple organ pathology. These rare mutations may cause inheritable hypertriglyceridemia, but they presented at a low frequency and could not be captured by standard genotyping array screenings. The identification of new mutations still relies on the direct sequencing of APOA5 gene of patients with hypertriglyceridemia with an unusual pattern, individually or in huge resequencing studies.

Mosaic supernumerary ring chromosome 1 in a three-generational family: 10-year follow-up report.

Additional small ring chromosome 1 is described with increasing rate of mosaicism in three generations. Ten years after the first examination, the mosaic rates in the patients were strikingly similar. An increase in the expression of phenotypic anomalies was also observed in the successive generations. FISH examinations following microdissection revealed signals which were positive for 1p13 and 1q21 indicating that the ring contained euchromatic segments on both ends. Additionally, array-CGH whole-genome analysis showed a single copy gain corresponding to band 1p12 to band 1q21-1 of chromosome 1 in the patients. The presence of euchromatic material from chromosome 1 in the ring suggests that the relationship between the cytogenetic findings and the clinical manifestation is likely causative. These unique observations might be explained by mitotic loss of the ring at early embryogenesis, and would indicate different mitotic vulnerability of certain chromosome abnormalities at early postzygotic stages versus later during development.

Excess of malignancies in grandparents of children with malformations? Short communication.

In a prospective study, the occurrence of malignancies in children referred to genetic counseling for congenital malformations, in their sibs, parents and grandparents was registered in 120 families by means of personal interviews. One hundred-and-twenty age matched subjects, admitted for acute respiratory infections or trauma, served as controls. No difference in the occurrence of tumors or leukemias between the two groups was found when the values of patients, sibs, and parents were compared. At the same time, the grandparents of probands with malformations had had significantly more malignancies than the grandparents of the controls. This may be explained by the fact that grandparents lived beyond the age of the usual onset of common cancers and leukemias.

Increased prevalence of factor V Leiden mutation in premature but not in full-term infants with grade I intracranial haemorrhage.

OBJECTIVES: In the current prospective study our aim was to analyse the distribution of the factor V Leiden (G1691A) mutation in preterm and full-term neonates with grade I intraventricular haemorrhage and in control neonates. STUDY METHOD: A group of 125 individually selected neonates with grade I intraventricular haemorrhage and 128 controls were investigated. RESULTS: The allele frequency was 7.2% in the total population of affected infants while it was 3.9% in the controls (p < 0.05); the latter corresponds to an average European allele frequency in healthy populations. When the infants were grouped as premature (<2,500 g and < or =36 weeks of gestational age) and appropriate for gestational age full-term infants the statistical analysis revealed an increased prevalence of the mutation in the premature group (10% allele frequency vs. 4.8% in the controls, p < 0.05), and a normal prevalence in the mature group (4.6 vs. 3.1%, respectively); therefore, the overall increase was due to the increase of incidence rate in preterm neonates. CONCLUSIONS: These data confirm our previous results and suggest that as the preterm and term infants differ from each other in haemorrhage susceptibility in many clinical particulars, carrying of the mutation has probably also a different impact in premature and in full-term infants with respect to the intraventricular haemorrhage.

A girl with cutaneous hyperpigmentation, café au lait spots and ring chromosome 15 without significant deletion.

Ring chromosome 15 [r(15)] syndrome is characterised by specific facial features, café au lait spots, failure to thrive, mental retardation and typically with a terminal deletion of the long arm of chromosome 15. We report a 2.5 year old girl showing normal growth and development, large hyperpigmented skin changes showing hypopigmentated areas inside, multiple café au lait spots and premature graying-like hypopigmentation of scalp hair. She had a karyotype of r(15) in peripheral lymphocytes and fibroblasts. By FISH analysis the breakpoint was located distal to locus D15S936 (15q26.3) and within 300 kb of the end of the chromosome, indicating no deletion of functional genes on 15q. Hyperpigmentation and café au lait spots are rare signs in ring chromosome syndromes, but with r(15) syndrome, café au lait spots have been described in about 30% of patients and have been considered to result from the deletion of gene(s) on distal 15q. Based on the frequent observation of patchy hyperpigmentation with the r(15) syndrome, absent hyperpigmentation in cases of distal 15q deletion without a ring chromosome, and the telomeric breakpoint location in our patient indicating no significant deletion, we propose that the cutaneous hyperpigmentation and café au lait spots in our proband represent effects of the r(15) chromosome but are not caused by the deletion of specific gene(s) on distal 15q. Patchy skin hypopigmentation is a well known nonspecific sign in cytogenetic mosaicism which is commonly seen in ring syndrome.

Mitochondrial DNA4977 deletion in brain of newborns died after intensive care.

Mitochondrial DNA (mtDNA) deletion affecting 4977 base pairs (mtDNA4977), the most common mtDNA mutation in humans, was analysed in brain specimens (frontal, temporal, and cerebellar cortices, caudate nucleus, thalamus, and hippocampus) and in other tissues (blood clot, liver, kidney, heart, and muscle) taken at autopsy of deceased neonates. mtDNA4977 deletion determined by polymerase chain reaction (PCR) could be demonstrated in each neonatal sample, however, quantity of mtDNA4977 deletion was less in the newborn samples than in those of the elderlies. Results obtained suggest that contrary to certain data mtDNA4977 deletion can be present in neonates. The mtDNA4977 deletion could be generated by perinatal hypoxia or temporary oxygen oversaturations during the intensive care of the neonates, as the mtDNA is sensitive to oxidative damage. In combination with other factors an additional causative role of mtDNA4977 deletion reported here cannot be ruled out in development of cerebral palsy or mental retardation of unknown origin often seen in neonates underwent neonatal intensive care procedures.

Association of nonsyndromic Wilms tumor with premature centromere division (PCD).

Wilms tumor was discovered in a 22-month-old otherwise healthy girl. Her pretreatment karyotype proved to be normal 46,XX with total premature division (PCD) in 21% of her lymphocyte mitoses. This phenomenon was not seen in the parents. PCD was found in less than 4% of lymphocyte mitoses of five other children with Wilms tumor. The individual finding provides further evidence for a relation of PCD to tumorigenesis; however, elucidation of the question needs further systematic studies.

Tissue specific mosaicism of trisomy 9 in a patient with severe torsion scoliosis.

We report on a female patient who had mosaic trisomy 9, presenting with severe scoliosis and mental retardation. Scoliosis is seldom reported in patients with mosaic trisomy 9 syndrome. FISH studies in our proband detected no trisomic cell line in the paravertebral muscle.

[Kennedy disease in a patient with progressive speech disorder]. / Kennedy-betegség egy progresszív beszédzavarban szenvedó férfiben.

Kennedy disease is an adult onset neuromuscular disease characterized by slowly progressive proximal and bulbar muscle weakness. The disease associates with gynecomastia, adult onset infertility and sensory neuropathy, and caused by pathologic expansion of CAG repeats at the N-terminal region of the androgen-receptor gene at Xq11-q12. We report on a patient presenting with slowly progressive muscle weakness of the lower extremities, progressive dysartry and swallowing difficulties. The clinical symptoms were not fully specific for the disease. Moreover the family history was suggestive for an autosomal dominant trait meaning a diagnostic pitfall at the original examination. Finally the firm diagnosis of the Kennedy disease was established by a polimerase chain reaction based method.

Cell formation in the human hippocampal formation from mid-gestation to the late postnatal period.

In the present study cell formation was studied in the human hippocampal formation from the 24th gestational week until the end of the first postnatal year. Proliferating cells were detected with the monoclonal antibody MIB-1. The cytoarchitectonic layers of Ammon's horn are formed before the 24th gestational week. In harmony with this observation, cell proliferation in the hippocampal ventricular zone is minimal after the 24th week. In addition, local cell multiplication in Ammon's horn is occasional and the proliferating cells are glial or endothelial cells. In contrast, cell formation continues in the hilar region of the dentate gyrus even after birth. Immature cells accumulate in the hilus, and at the border between the hilus and the granule cell layer throughout the first eight postnatal months. The subgranular zone of the dentate gyrus becomes a cell sparse area at about the 11th postnatal month, indicating that immature cells from the hilus have already migrated to the granule cell layer and differentiated into granule cells. There is an increase in glial cell proliferation both in Ammon's horn and the dentate gyrus at the 11.5th postnatal month suggesting the onset of myelination by the end of the first year. Our findings indicate that most pyramidal neurons of Ammon's horn are generated in the first half of pregnancy and no pyramidal neurons are formed after the 24th gestational week. In contrast, granule cells of the dentate gyrus proliferate in a decreasing rate during the second half of pregnancy and after birth. Proliferating neuronal precursors occur in a low percentage in the dentate gyrus of 3-, 5- and 11.5-month-old children.

Distal deletion, del(2)(q33.3q33.3), in a patient with severe growth deficiency and minor anomalies.

We report on an 18-month-old boy with a 2q33.3 deletion. The clinical findings observed in the propositus included minor anomalies of face and distal limbs, intrauterine and postnatal growth retardation, microcephaly and, so far, moderate developmental delay. Conventional GTG banded chromosome analysis indicated a small deletion in distal 2q. Subsequent analysis by fluorescent in situ hybridization (FISH) using different probes allowed us to narrow down the deletion to most or all of segment 2q33.3. This case shows the importance of the application of different YAC probes for a precise determination of breakpoints in small interstitial deletions.

[Vascular diseases, spina bifida and schizophrenia in a single family associated with the heterozygote mutation of the heat-sensitive variant of methylenetetrahydrofolate reductase]. / Errendszeri betegségek, spina bifida és schizophrenia egy családon belüli együttes elófordulása a metilén-tetrahidrofolsav-reduktáz enzim hóérzékeny variánsának heterozigóta mutációjával.

Homozygous mutation of the thermolabile variant of methylene tetrahydrofolate reductase (MTHFR) may result in hyperhomocystinemia, leading to an increased risk for early cardiovascular disease, neural tube defects, and possibly major depression, schizophrenia. According to recent studies heterozygosity for the thermolabile variant of the MTHFR gene mutation is also more frequent in patients with thrombotic disease compared to that in the average population. We report on a family with different types of early vascular disease. In four consecutive generations MTHFR heterozygosity was detected: in the proband and in her mother, grandfather and daughter. Further conditions of the family members, possibly due to carrying the mutation, came to light by the pedigree analysis and examinations. The patient had pulmonary emboli at young age, her aunt died of spina bifida shortly after birth. The patient's mother suffers from schizophrenia and depression. The grandfather had pulmonary emboli, her sister with spina bifida occulta also carries the same mutation, as does her daughter who is sofar asymptomatic. In other asymptomatic members of the family no mutations were found. Unexpectedly, hyperhomocystinemia was detected in all heterozygote individuals. Our study demonstrates the necessity for folic acid therapy in mutation carriers to prevent early vascular events, depression and schizophrenia, and also to reduce the risk for neural tube defects in a preconception setting.

[Clinical and genetic consequences of ring chromosome, a structural genome mutation]. / Gyúrúkromoszóma, egy strukturális genommutáció klinikai és genetikai következményei.

Ring chromosome is a peculiar genetic anomaly which may cause phenotypic abnormalities even without a loss of genetic material. The ring formation of chromosome ends induces difficulties in the sister chromatid separation at cell division, resulting in increased cell death rate through the generation of secondary aneuploid cells. Based on the in vitro analyses of own cases and a review of more than 200 case reports published in the literature, the author presents some conclusions on "ring syndrome", a non-specific clinical manifestation of ring formation of any chromosome, consisting of the lack of (or poorly expressed) organic manifestations, mild or borderline mental retardation, and a severe growth failure which is not explained by organic, biochemical, or endocrine findings. It is also suggested that the phenotypic manifestation of a ring chromosome is even less expressed when the ring is transmitted to the next generation. Based on observations of ring behaviour and the clinical phenotypes in a 3-generational family with a mosaic supernumerary ring, it is not unrealistic to assume that there is a transgenerational increase in the severity of the clinical manifestation resulting from a less efficient elimination process against the ring (cytogenetic anticipation).

Cell formation in the cortical layers of the developing human cerebellum.

Cell proliferation has been studied in the human cerebellar cortex between the 24th gestational week and the 12th postnatal month. Intensive cell formation has been found in the external granular layer (EGL) of the human cerebellum, where the highest cell proliferation rate occurs between the 28th and 34th gestational weeks. This is followed by a gradual decrease that lasts up to the eighth postnatal month. As late in development as the fifth postnatal month, still 30% of cells of the EGL are labeled with the monoclonal antibody Ki-67, which is specific for dividing cells. The width of the EGL remained unchanged from the 28th gestational week to the end of the first postnatal month, when it starts to decrease and completely disappears by the 11th postnatal month. Large number of Ki-67 labeled cells occurs in the internal granular layer (IGL) between the 24th and 28th gestational weeks. From the 36th week onwards, the labeling index is less than 1%, although a few labeled cells have always been found in this layer even in the late postnatal period. Labeled cells are distributed in the entire width of the IGL. However, from the 34th gestational week, almost all labeled cells are found among and directly below the Purkinje cells. Their position, the nuclear features, and their occasionally stained cell processes suggest that those are Bergmann glial cells. There are few Ki-67 labeled cells in the molecular layer (ML) and in the white matter (WM) of the cerebellum throughout the examined period. It is likely that most of these are glial cells. Pyknotic index has been found to be small in all layers of the cerebellum during the examined period.