Assignment of Tangier disease to chromosome 9q31 by a graphical linkage exclusion strategy.

A low level of high density lipoprotein (HDL) cholesterol is a strong predictor of ischaemic heart disease (IHD) and myocardial infarction. One cause of low HDL-cholesterol is Tangier disease (TD), an autosomal codominant inherited condition first described in 1961 in two siblings on Tangier Island in the United States of America. Apart from low HDL-cholesterol levels and an increased incidence of atherosclerosis, TD is characterized by reduced total cholesterol, raised triglycerides, peripheral neuropathy and accumulation of cholesteryl esters in macrophages, which causes enlargement of the liver, spleen and tonsils. In contrast to two other monogenic HDL deficiencies in which defects in the plasma proteins apoA-I and LCAT interfere primarily with the formation of HDL (refs 7-10), TD shows a defect in cell signalling and the mobilization of cellular lipids. The genetic defect in TD is unknown, and identification of the Tangier gene will contribute to the understanding of this intracellular pathway and of HDL metabolism and its link with IHD. We report here the localization of the genetic defect in TD to chromosome 9q31, using a genome-wide graphical linkage exclusion strategy in one pedigree, complemented by classical lod score calculations at this region in a total of three pedigrees (combined lod 10.05 at D9S1784). We also provide evidence that TD may be due to a loss-of-function defect.

The clinical utility of MRI in patients with neurodevelopmental disorders of unknown origin.

INTRODUCTION: Neuroimaging of the brain in the diagnostic work-up of patients with neurodevelopmental disorders is a matter of continuing debate. Recommendations range from performing brain imaging in all patients with neurodevelopmental disorders to performing an MRI only in those with indication on clinical examinations. Important indications for neuroimaging are head size abnormalities and focal neurological findings. METHODS: Patients with neurodevelopmental disorders of unknown origin (n = 410), referred to a specialized tertiary diagnostic center for neurodevelopmental disorders were included in a retrospective analysis. A 1-day work-up, including an MRI of the brain was performed. Studied were the: (i) yield of MRI scans of the brain and (ii) associations of specific clinical symptoms/signs with abnormal and diagnostic MRI scans. RESULTS: (i) In 30.7% of the 410 patients with neurodevelopmental disorders (n = 126), abnormal MRI scans were observed, leading to an etiological diagnosis in 5.4% of the patients (n = 22). (ii) Pyramidal disorders (P = 0.001), epilepsy (P = 0.04) and an abnormal head circumference (P = 0.02) were associated with an abnormal MRI scan. The presence of one of the following neurological symptoms/signs: movement disorders, pyramidal disorders, epilepsy, or an abnormal head circumference was associated with a diagnostic MRI scan (P < 0.001) (diagnostic MRI % in neurological versus no neurological symptoms/signs, 13.0% versus 1.9%). CONCLUSION: Neuroimaging of the brain in a tertiary care center for patients with neurodevelopmental disorders of unknown origin is useful, especially in case of neurological symptoms/signs.

NGS panel analysis in 24 ectopia lentis patients; a clinically relevant test with a high diagnostic yield.

BACKGROUND: Several genetic causes of ectopia lentis (EL), with or without systemic features, are known. The differentiation between syndromic and isolated EL is crucial for further treatment, surveillance and counseling of patients and their relatives. Next generation sequencing (NGS) is a powerful tool enabling the simultaneous, highly-sensitive analysis of multiple target genes. OBJECTIVE: The aim of this study was to evaluate the diagnostic yield of our NGS panel in EL patients. Furthermore, we provide an overview of currently described mutations in ADAMTSL4, the main gene involved in isolated EL. METHODS: A NGS gene panel was analysed in 24 patients with EL. RESULTS: A genetic diagnosis was confirmed in 16 patients (67%). Of these, four (25%) had a heterozygous FBN1 mutation, 12 (75%) were homozygous or compound heterozygous for ADAMTSL4 mutations. The known European ADAMTSL4 founder mutation c.767_786del was most frequently detected. CONCLUSION: The diagnostic yield of our NGS panel was high. Causative mutations were exclusively identified in ADAMTSL4 and FBN1. With this approach the risk of misdiagnosis or delayed diagnosis can be reduced. The value and clinical implications of establishing a genetic diagnosis in patients with EL is corroborated by the description of two patients with an unexpected underlying genetic condition.

Novel ATP6V1B1 and ATP6V0A4 mutations in autosomal recessive distal renal tubular acidosis with new evidence for hearing loss.

Autosomal recessive distal renal tubular acidosis (rdRTA) is characterised by severe hyperchloraemic metabolic acidosis in childhood, hypokalaemia, decreased urinary calcium solubility, and impaired bone physiology and growth. Two types of rdRTA have been differentiated by the presence or absence of sensorineural hearing loss, but appear otherwise clinically similar. Recently, we identified mutations in genes encoding two different subunits of the renal alpha-intercalated cell's apical H(+)-ATPase that cause rdRTA. Defects in the B1 subunit gene ATP6V1B1, and the a4 subunit gene ATP6V0A4, cause rdRTA with deafness and with preserved hearing, respectively. We have investigated 26 new rdRTA kindreds, of which 23 are consanguineous. Linkage analysis of seven novel SNPs and five polymorphic markers in, and tightly linked to, ATP6V1B1 and ATP6V0A4 suggested that four families do not link to either locus, providing strong evidence for additional genetic heterogeneity. In ATP6V1B1, one novel and five previously reported mutations were found in 10 kindreds. In 12 ATP6V0A4 kindreds, seven of 10 mutations were novel. A further nine novel ATP6V0A4 mutations were found in "sporadic" cases. The previously reported association between ATP6V1B1 defects and severe hearing loss in childhood was maintained. However, several patients with ATP6V0A4 mutations have developed hearing loss, usually in young adulthood. We show here that ATP6V0A4 is expressed within the human inner ear. These findings provide further evidence for genetic heterogeneity in rdRTA, extend the spectrum of disease causing mutations in ATP6V1B1 and ATP6V0A4, and show ATP6V0A4 expression within the cochlea for the first time.

Effects of neonatal dexamethasone treatment on hypothalamo-pituitary adrenal axis and immune system of the rat.

Synthetic glucocorticoids (GC) are widely used drugs, also in the prevention of diseases that occur in the preterm newborn. Previously we have found that GC treatment of pregnant rats resulted in a persistent increase in the ratio of AVP over CRH in the mediobasal hypothalamus, and in an increased CD4/CD8 ratio in the thymus of the newborn. The objective of the present study was to investigate whether such effects were also seen after neonatal GC exposure, given in clinically-relevant doses. Dexamethasone-21-phosphate (DEX; 1.2 microg/g BW, i.p.) was given at day 5 and day 7 after birth. At day 18, 33, and 48 after birth effects of GC on the HPA-axis, and on CD4+ and CD8+ T cells in thymus and spleen were examined. Neonatal DEX treatment temporarily increased (p < 0.01) AVP stores in the external zone of the median eminence (ZEME) on day 18 after birth, and did not affect CRH stores. Resting plasma levels of ACTH and corticosterone remained unchanged after neonatal DEX treatment at any time interval studied. In the thymus and spleen, neonatal DEX treatment decreased (p < 0.0001) T cell numbers on day 18 after birth. Furthermore, neonatal DEX treatment increased (p < 0.01) the ratio of mature CD4-CD8+ over CD4-CD8+ thymocytes on day 18 after birth, but not on day 33 and day 48 after birth. In conclusion, neonatal DEX treatment has temporary effects on peptide expression in hypothalamic CRH neurons, and on thymocyte maturation. Apparently, neonatal exposure to GC affects potentially sensitive targets within the endocrine system and immune system but these alterations are reversible and readjusted during development.

Effects of short-term dexamethasone treatment during pregnancy on the development of the immune system and the hypothalamo-pituitary adrenal axis in the rat.

The effects of glucocorticoid (GC) treatment on the mature immune and neuroendocrine system are known to be reversible. However, prenatal GC exposure may have irreversible consequences on the development of the newborn. In this study, possible long-lasting effects of short-term prenatal GC treatment were examined on the developing thymus, spleen and hypothalamo-pituitary adrenal axis (HPA axis). Female rats were given dexamethasone (DEX, 400 micrograms, i.p.) on day 17 and 19 of pregnancy and offspring was studied at several time intervals (1-20 days) after birth, for examination of thymus, spleen, hypothalamus and blood plasma. Examination of thymus and spleen revealed that prenatal exposure to DEX resulted in decreased T cell numbers in thymus and spleen on day 1 after birth. Thymus regeneration after DEX exposure both during pregnancy and in adult life was completed after 24 days. However, the kinetics of regeneration of the thymi after prenatal DEX exposure were different from that seen after DEX in adult life. Whereas DEX treatment during pregnancy resulted in an increased ratio of CD4+/CD8- thymocytes over CD4-/CD8+ thymocytes compared to control groups on day 7 and day 20 after birth (time X treatment interaction; P < 0.05), DEX treatment in adult life did not change this ratio. T cell numbers in the spleen were significantly decreased at all neonatal ages studied. Regarding the hypothalamus, prenatal exposure to DEX altered the pattern of neonatal changes in peptide expression in corticotropin-releasing hormone neurons, with a selective reduction in CRH storage in the median eminence (7 and 9 days after birth) and an increase in AVP storage (9 and 20 days after birth). The ratio of AVP over CRH was significantly increased at all developmental ages studied. No effects were seen on basal ACTH and corticosterone levels in plasma. In conclusion, the kinetics of thymus regeneration after DEX exposure during pregnancy were different from that seen after DEX exposure in adult life. Prenatal DEX exposure also seemed to delay the migration of T cells into the spleen. Furthermore, prenatal DEX treatment exerted major effects on hypothalamic CRH neurons that maintained for at least 20 days after birth, which points towards an enhanced stress responsiveness of the HPA axis in later life.

Two cases of the caudal duplication anomaly including a discordant monozygotic twin.

We present two unrelated patients with various duplications in the caudal region. One patient presented with a duplication of the distal spine from L4, left double ureter, duplication of the vagina and cervix, and duplication of the distal colon. The second patient was diagnosed with a duplication of the colon, bladder, vagina and uterus. The first patient had an unaffected monozygotic twin sister. Dominguez et al. [1993: Am J Dis Child 147:1048-1052] presented six similar cases, and introduced the name "caudal duplication syndrome." The pathogenesis of the caudal duplication anomaly is unclear. The possibility of a polytopic primary developmental field defect or a disruptive sequence are discussed. On the other hand, somatic or germline mutations in certain developmental genes could be involved, as illustrated by the mouse mutations disorganisation and fused. DNA-analysis of the AXIN1 gene, the human homologue of the gene responsible for fused, performed in our first patient, did not show any apparent pathogenic mutation.

A Spin Filter system for the study of algal interactions.

In Spin Filter flasks interacting populations of algae can be grown in such a way that they are kept separate spatially but remain in close contact chemically. The rotating filter unit of the flasks is a solution to the clogging problem. In experiments with this system Chlamydomonas globosa was always inhibited slightly by Chlorococcum ellipsoideum, but Chlorococcum was only inhibited by Chlamydomonas when the latter had an initial advantage.

Evaluation of the contents of mineral water, spring water, table water and spa water.

The present study surveys and evaluates the mineral contents of the speciality drinking waters currently available in Germany. A total of 257 producers and 226 reports of water contents have been consulted. The minerals sodium, calcium, potassium and magnesium together with the halogens chlorine and fluorine have been of special interest here in view of their significance in infant feeding, caries prevention, and possible influence on the drinking waters, the sodium concentrated from 0.9 mg/l (Finkenbachquelle, mineral water) to 12830 mg/l (Bad Mergentheimer Albertquelle, spa water). The potassium values also, range broadly, between 1.4 mg/l (Kisslegger Sprudel, mineral water) and 611 mg/l (Obenauer Löwensprudel, mineral water). Fluoride concentrations were given special attention, since they are of significance in caries prevention, for the strength of bones, and also considerable importance in connection with the danger of fluorosis. Numerous commercial mineral waters and table waters contain too little fluoride (0.007 mg/l, Kirkeler Waldquelle, mineral water) or have fluoride concentrations over 4.1 mg/l (Hardenstein Brunnen, mineral water). The latter appear inappropriate, especially for small children. On the basis of the considerable variations of mineral and halogen contents in commercial mineral waters and table waters, the concentration of crucial trace elements should be clearly stated on the labels of the bottles, along with relevant information concerning possible effects.

[Norplant in The Netherlands]. / Norplant in Nederland.

PIP: An 18-year old patient bearing a subcutaneous Norplant implant in the left upper arm for 2 years visited a gynecological clinic. The implant rods were removed under local anesthesia because of the increasing pigmentation of the skin, and she switched to oral contraceptive use. Norplant contains a total of 216 mg of levonorgestrel (LNG) in 6 silastic rods, each 3.4 cm long. Norplant-2 consists of 3 rods with a length of 4.4 cm providing a total of 140 mg of LNG. It has been in use since 1974 in Chile, and subsequently in Brazil, Indonesia, Thailand, Africa, and to a lesser extent in Scandinavia. It works via the continuous release of 30-50 mcg doses of progesterone daily that induces cervical mucous changes whereby sperm penetration is thwarted; nidation does not occur, and ovulation is also often inhibited. The Pearl-Index reaches .1-1.1 in the first 5 years of use. The most important side effects are menstruation changes (oligo- and amenorrhea), weight gain, and headache. The continuation rate is similar to that of the IUD: 95% through the 1st year of use, and 75% through 3 years reported from Chile and China. Reversibility is a major advantage: 50% of women become pregnant within 3 months after removal, 86% within 1 year, and 93% within 2 years. In the Netherlands sits acceptance is clearly distinct from prevalence in Chile and China, and it has only a minor role in applicability when other contraceptives fail.^ieng

[Carrier detection in cystic fibrosis. Various illustrative examples]. / Dragerschaponderzoek bij cystic fibrosis. Enkele illustratieve voorbeelden.

Until 1989 carrier detection in families with cystic fibrosis (CF) took place by means of linkage analysis with polymorphic DNA markers. This is an indirect method to demonstrate carriership. For linkage analysis it is often essential that there is patient material available. Since the identification of the CF gene, direct DNA analysis of the most frequent CF mutations is possible. This allows direct demonstration of carriership by means of DNA analysis in the majority of cases, without the necessity always to investigate family members. Carriership detection of persons not related to CF patients, for example partners of CF carriers, is with this method also possible. In cases where none of the frequent CF mutations can be found, linkage analysis may still prove helpful. In this article we demonstrate some clinical examples of carrier investigation.

Faecal SIgA secretion in infants fed on pre- or probiotic infant formula.

Secretory immunoglobulin A (SIgA) plays an important role in the defence of the gastrointestinal tract. The level of faecal SIgA antibody is associated with increased neutralization and clearance of viruses. Formula-fed infants who lack the transfer of protective maternal SIgA from breast milk may benefit from strategies to support maturation of humoral immunity and endogenous production of SIgA. We aimed at studying the effects of standard, prebiotic and probiotic infant formulas on the faecal SIgA levels. At birth, infants of whom the mother had decided not to breastfeed were allocated to one of three formula groups in a randomized, double-blind fashion. Nineteen infants received standard infant formula; 19 received prebiotic formula containing a specific mixture of 0.6 g galacto-oligosaccharides (GOS)/fructo-oligosaccharides (FOS)/100 ml formula and 19 received probiotic formula containing 6.0 x 10(9) cfu Bifidobacterium animalis/100 ml formula. Faecal samples were taken on postnatal day 5, day 10, wk 4 and every 4 wk thereafter until wk 32. SIgA in faeces was determined by an enzyme-linked immunosorbent assay. During the intervention, infants fed on prebiotic formula showed a trend towards higher faecal SIgA levels compared with the standard formula-fed infants reaching statistical significance at the age of 16 wk. In contrast, infants fed on the probiotic formula showed a highly variable faecal SIgA concentration with no statistically significant differences compared with the standard formula group. Formula-fed infants may benefit from infant formulas containing a prebiotic mixture of GOS and FOS because of the observed clear tendency to increase faecal SIgA secretion. Adding viable B. animalis strain Bb-12 to infant formula did not reveal any sign for such a trend.

Increased DNA methylation at the AXIN1 gene in a monozygotic twin from a pair discordant for a caudal duplication anomaly.

The AXIN1 gene has been implicated in caudal duplication anomalies. Its coding region was sequenced in both members of a monozygotic (MZ) twin pair discordant for a caudal duplication anomaly, but no mutation was found. Using bisulfite sequencing, we examined methylation at the promoter region of the AXIN1 gene in these twins and in twin and age-matched singleton controls. Methylation of the promoter region in peripheral blood mononucleated cells was variable among individuals, including MZ pairs. In the MZ pair discordant for the caudal duplication, this region of the affected twin was significantly more methylated than that of the unaffected twin (P < .0001), which was significantly more methylated than those of the controls (P = .02). We have confirmed that this CpG island does function as a promoter in vitro and that its activity is inversely proportional to the extent of methylation. This finding raises the possibility that hypermethylation of the AXIN1 promoter, by mechanisms as yet undetermined, is associated with the malformation. This case may be paradigmatic for some cases of MZ discordance.

Mitochondrial dysfunction in a patient with Joubert syndrome.

Joubert syndrome is a genetically heterogeneous disorder. The diagnostic criteria include episodic hyperventilation, abnormal eye movements, psychomotor retardation, hypotonia, ataxia, and the characteristic neuro-imaging findings (molar-tooth sign). Many of these clinical features have been observed in new-borns with mitochondrial disorders as well. Congenital brain malformations, including cerebellar hypoplasia, have been described in pyruvate dehydrogenase deficiency. Malformations of the vermis and the cerebellar peduncles, with the lack of axonal decussations, however, are characteristic for Joubert syndrome but unique in patients with mitochondrial disorders. Here, we describe a child with Joubert syndrome presenting with primary lactic acidemia, decreased pyruvate oxidation rates, decreased ATP production, and a mildly decreased pyruvate dehydrogenase complex activity measured in a fresh muscle biopsy. Sequence analysis of the PDHc E1 alpha gene and the PDHX genes revealed no mutations. The patient received continuous feeding through a feeding tube for two years and showed a significant clinical improvement with a complete resolution of the chronic lactic acidemia. A second muscle biopsy revealed significantly decreased pyruvate oxidation rates and ATP production, but a normal pyruvate dehydrogenase complex activity. We suggest that the described mitochondrial dysfunction in our patient is secondary to an underlying mutation leading to Joubert syndrome.

Mosaic trisomy (8)(p22 --> pter) in a fetus caused by a supernumerary marker chromosome without alphoid sequences.

OBJECTIVE: Our objective was to characterise a marker chromosome in cultured amniocytes of a fetus with a mos 47,XX,+mar[3]/46,XX[14] karyotype. METHODS: The indication for prenatal cytogenetic analysis of cultured amniocytes was advanced maternal age. Classic banding techniques (GTG- and C-banding) were performed. Microdissection combined with reverse painting was used to disclose the exact origin of the marker; the result was confirmed by chromosome painting and FISH with band-specific probes. RESULTS: Analysis of GTG-banded chromosomes showed a small marker chromosome in 3 of the 17 colonies analysed. Subsequently, C-banding showed no alphoid sequences, suggesting the presence of a neocentromere. The parent's karyotypes were normal. After normal ultrasound findings, the parents decided to continue the pregnancy. Chromosome analysis in peripheral blood after birth demonstrated that the marker chromosome was present in 50% of the lymphocytes. Using microFISH, the marker was further characterised and appeared to be derived from chromosome region (8)(p22 --> pter). CONCLUSION: Accurate identification of the marker chromosome was very important for prenatal counselling. Combining the results of GTG- and C-banding analysis with the results of the (micro)FISH, we concluded that the patient's karyotype is: mos 47,XX,+mar.rev ish der(8)(p22 --> pter)[50]/46,XX[50].

To see or not to see, a difficult question in the ileocaecal region.

A case is reported in which two diagnostic procedures were used to visualize colonic pathology, i.e. radiography and endoscopy. Neither of these methods led to the correct diagnosis. This case illustrates the need to combine and integrate the information obtained with the two methods, with respect to both the localization and the nature of the pathological process.

Ehlers-Danlos syndrome type IV: unusual congenital anomalies in a mother and son with a COL3A1 mutation and a normal collagen III protein profile.

A mother and son with Ehlers-Danlos syndrome (EDS) type IV and unusual congenital anomalies are described. The congenital anomalies include, in the mother, amniotic band-like constrictions on one hand, a unilateral clubfoot, and macrocephaly owing to normal-pressure hydrocephaly and, in the son, an esophageal atresia and hydrocephaly. Protein analysis of collagen III in cultured fibroblasts of the mother showed no abnormalities. However, DNA analysis of the COL3A1 gene revealed a pathogenic mutation (388G-->T) in both the mother and the son. The possible relationship between the observed congenital anomalies and EDS IV are discussed. We stress that DNA analysis of COL3A1 should be performed in all patients when there is a strong suspicion of EDS IV, despite negative findings in a collagen protein analysis.