Potential errors with rapid analysis techniques: partial duplication 21q resulting from a paternal paracentric insertion uncovered in chorionic villus sampling by fluorescence in situ hybridization

We report on partial duplication 21q resulting from a paternal insertion identified during prenatal diagnosis. While performing interphase fluorescence in situ hybridization (I-FISH), we were able to identify 3 signals of the LSI 21 Spectrum Orange probe with chorionic villus sampling. Using standard cytogenetic analysis, I-FISH and GTG banding, structural aberrations in 21q in the parents and in the fetus could not be reliably determined. Applying metaphase fluorescence in situ hybridization (M-FISH), we identified a recombinant chromosome 21 carrying an interstitial duplication of the Down syndrome critical region inherited from the father. Both data from our analysis and published literature recommend the use of rapid testing methods such as I-FISH and standard cytogenetic analysis in prenatal diagnosis. It became obvious that I-FISH would not detect such a particular aberration. Thus, karyotyping, I-FISH and M-FISH should be performed in all Down syndrome cases.

Evaluation of a candidate breast cancer associated SNP in ERCC4 as a risk modifier in BRCA1 and BRCA2 mutation carriers. Results from the Consortium of Investigators of Modifiers of BRCA1/BRCA2 (CIMBA)

Background:

In this study we aimed to evaluate the role of a SNP in intron 1 of the ERCC4 gene (rs744154), previously reported to be associated with a reduced risk of breast cancer in the general population, as a breast cancer risk modifier in BRCA1 and BRCA2 mutation carriers.

Methods:

We have genotyped rs744154 in 9408 BRCA1 and 5632 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) and assessed its association with breast cancer risk using a retrospective weighted cohort approach.

Results:

We found no evidence of association with breast cancer risk for BRCA1 (per-allele HR: 0.98, 95% CI: 0.93–1.04, P=0.5) or BRCA2 (per-allele HR: 0.97, 95% CI: 0.89–1.06, P=0.5) mutation carriers.

Conclusion:

This SNP is not a significant modifier of breast cancer risk for mutation carriers, though weak associations cannot be ruled out.

The TP53 Arg72Pro and MDM2 309G>T polymorphisms are not associated with breast cancer risk in BRCA1 and BRCA2 mutation carriers

Background:

The TP53 pathway, in which TP53 and its negative regulator MDM2 are the central elements, has an important role in carcinogenesis, particularly in BRCA1- and BRCA2-mediated carcinogenesis. A single nucleotide polymorphism (SNP) in the promoter region of MDM2 (309T>G, rs2279744) and a coding SNP of TP53 (Arg72Pro, rs1042522) have been shown to be of functional significance.

Methods:

To investigate whether these SNPs modify breast cancer risk for BRCA1 and BRCA2 mutation carriers, we pooled genotype data on the TP53 Arg72Pro SNP in 7011 mutation carriers and on the MDM2 309T>G SNP in 2222 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). Data were analysed using a Cox proportional hazards model within a retrospective likelihood framework.

Results:

No association was found between these SNPs and breast cancer risk for BRCA1 (TP53: per-allele hazard ratio (HR)=1.01, 95% confidence interval (CI): 0.93–1.10, P_trend=0.77; MDM2: HR=0.96, 95%CI: 0.84–1.09, P_trend=0.54) or for BRCA2 mutation carriers (TP53: HR=0.99, 95%CI: 0.87–1.12, P_trend=0.83; MDM2: HR=0.98, 95%CI: 0.80–1.21, P_trend=0.88). We also evaluated the potential combined effects of both SNPs on breast cancer risk, however, none of their combined genotypes showed any evidence of association.

Conclusion:

There was no evidence that TP53 Arg72Pro or MDM2 309T>G, either singly or in combination, influence breast cancer risk in BRCA1 or BRCA2 mutation carriers.

[Muscular hypotonia, developmental retardation, speech delay and mildly dysmorphic features: 22q13 deletion syndrome (Phelan-McDermid Syndrome) as an important differential diagnosis]

BACKGROUND

Clarifying the cause of global developmental and speech delay is of considerable significance in pediatrics. We present the clinical phenotype of the 22q13 deletion syndrome - also known as Phelan-McDermid syndrome - and show the diagnostic options.

PATIENT

We report on a female patient with muscular hypotonia, tall stature, minor facial dysmorphism, retarded motor and mental development, and severe speech delay.

METHOD

Chromosomal analysis was performed first on peripheral lymphocytes on GTG-banded chromosomes. Fluorescence in situ hybridization (FISH) analysis was carried out using the dual-color LSI DiGeorge/VCFS Region Probe (TUPLE1, N25) (Vysis/Abbott) and the subtelomeric probe tel 22q13.3 (Tel Vysion 22q).

RESULTS

The analysis of metaphase chromosomes at 450 band resolution showed a normal female karyotype 46,XX. FISH analysis revealed a 22q13 deletion.

CONCLUSION

Muscular hypotonia and developmental delay are non-specific findings observed in many genetic syndromes. In association with severe speech delay and normal or advanced growth pediatricians should consider 22q13 deletion syndrome as a potential cause and initiate a genetic examination.

Evidence for a founder effect of the germline fumarate hydratase gene mutation R58P causing hereditary leiomyomatosis and renal cell cancer (HLRCC)

We report on the results of clinical investigation, pedigree analysis, mutation screening and haplotyping in a family with the syndrome of multiple cutaneous and uterine leiomyomas (MCUL1) and a germline missense mutation (R58P) in the fumarate hydratase gene (FH). We provide evidence for a founder effect for the identified mutation and distant relationship of our family to another familial case of MCUL1 associated with renal cell cancer, which was recently published with the same mutation.

Hereditäre multiple Exostosen

Hereditary multiple exostosis (HME), a disorder inherited in an autosomal dominant manner, is characterized by multiple projections of bone, mainly at the extremities. The risk of malignant transformation of the exostoses is estimated to be up to 2%. The most common underlying cause of the disease involves mutations in either the EXT1 or the EXT2 gene. We report on the clinical and molecular findings in a family affected with HME.A mother and her three children from different partnerships, all clinically diagnosed with HME, were referred for genetic counseling. Subsequently, molecular analysis of the EXT1 gene was performed according to standard procedures. We identified a mutation in the EXT1 gene in all four affected family members (delA in codon 133). This mutation has not been previously described and is suggested to cause the disease in this family. Identification of disease causing mutations in patients with HME and their relatives can help to improve the clinical management of tumor prevention, early tumor detection, and orthopedic therapy.

Clinical significance and neuropathology of primary MADD in C34-T and G468-T mutations of the AMPD1 gene

OBJECTIVE

Primary myoadenylate deaminase deficiency (MADD) is probably the most frequent inborn metabolic myopathy with a prevalence of up to 2%. It is the result of mutations in the AMPDI gene, the most common of which is a C34-T transition in exon 2. The importance of the more rare mutation G468-T in exon 5 is uncertain. Primary objective was to elucidate the clinical significance of the enzyme disorder, which remains unclear since its first description in 1978. We further examined the existence of an association of MADD with other muscle disorders, such as malignant hyperthermia and rhabdomyolysis, as was suspected in earlier studies.

MATERIAL AND METHODS

In a large collection of 1673 muscle biopsies that had been stored deep frozen we identified 33 cases of primary MADD, 12 of which without any other coinciding muscle diseases, by histochemical, biochemical and molecular genetic examinations. Clinical and laboratory data was collected. By additional examination of randomly chosen blood samples we identified one person carrying the rare compound heterozygosity C34-T/ G468-T, who was examined in clinical respects and a muscle biopsy was taken.

RESULTS

As underlying mutation, the most common transition C34-T/C 143-T was detected in 33 cases. One patient carried the compound heterozygosity C34-T/G468-T. The overall frequency of MADD in the contingent was 1.8%. Only three patients out of 12 with isolated primary MADD suffered from muscle complaints, one of whom did not experience the typical symptoms of exercise related myalgia, muscle cramps and weakness as described by Fishbein. The patient carrying C34-T/G468-T was a fully healthy female. She had never experienced any muscle complaints. Any association with other neuromuscular disorders, if not completely ruled out, was found to be very unlikely.

CONCLUSION

The results suggest that MADD itself is unlikely to be solely responsible for the manifestation of muscular symptoms. It is probable that either the loss of a compensation mechanism or coexistent disturbances in muscle metabolism which are unidentified so far are required for the emergence of complaints.

Another case of autosomal dominant exstrophy of the bladder

OBJECTIVE

Exstrophy of the bladder is a rare malformation due to an anterior midline defect. Most cases of this condition with variable expression occur sporadically, but there are some cases indicative of a strong genetic component apart from environmental factors. This is a report about another rare mother-child pair with bladder exstrophy.

METHODS

We present the clinical data of a familial case of bladder exstrophy with an affected mother and her equally affected male fetus.

RESULTS

Prenatal diagnosis of bladder exstrophy in the fetus was assessed by ultrasound at the 19th gestational week and was confirmed after termination of pregnancy at the 21st gestational week.

CONCLUSION

The present case may be additional evidence for an autosomal dominant inherited variant of this malformation complex with implication for counselling of affected patients.

Molekulargenetischer Mutationsnachweis im PTPN11-Gen beim Multiple-Lentigines- (LEOPARD-)Syndrom

BACKGROUND AND OBJECTIVE

LEOPARD syndrome (MIM #151100) is a rare autosomal dominant condition with characteristic skin anomalies, facial dysmorphism, hypertelorism, cardiac anomalies, and occasional conductive hearing loss. Mutations in the PTPN11 gene are described as the causal gene defect for the clinical features of Noonan syndrome (MIM #163950), but also for LEOPARD syndrome. For confirmation of the clinical diagnosis of multiple lentigines syndrome, the molecular genetic mutation analysis in the PTPN11 gene could be helpful.

PATIENTS/METHODS

We report on a family with LEOPARD syndrome in which the mutation analysis in the father and his daughter in the PTPN11 gene was carried out us:ng PCR, DHPLC, and automated sequencing.

RESULTS

We could identify both father and daughter as carriers of the mutation Y279C in the PTPN11 gene, which is known as a disease-related mutation.

CONCLUSIONS

The allelic affinity to Noonan syndrome could thus be further supported.

Partial trisomy 22 resulting from rearrangements between chromosomes 11/22 and 16/22: a report of two cases

Two male infants with partial trisomy 22 resulting from a rearrangement between chromosomes 11/22 and 16/22 were admitted to the Children's Hospital of the University of Leipzig within the space of two months. The characteristic phenotype of the infants is described and compared with the data on liveborn infants with trisomy 22, as reported in the literature. One of the infants reported here showed a prenatally detected hygroma colli. To the best of our knowledge this is the first description of a hygroma colli in this chromosomal disorder.

CONCLUSION

Infants with trisomy 22 can present with variable phenotypes. It is important to bear the phenotype of chromosome 22 infants in mind.

[Current aspects of the diagnosis of malignant hyperthermia]

OBJECTIVES

The aim of this work was to give a survey of experiences and results obtained over a period of 15 years of diagnosis of malignant hyperthermia in the MH centre in Leipzig. The new branch of MH diagnosis, the molecular genetics and its general diagnostic potential will be presented in more detail.

METHODS

The in vitro contracture test (IVCT), which has been used in our department since 1986, represents the standard method for determining disposition to MH and in addition, suspected MH events were analysed by the clinical grading scale (CGS). In 1999, the diagnosis of MH in our centre was supplemented by molecular genetic examination of the skeletal ryanodine receptor gene (RYR1).

RESULTS

A total of 1,456 muscle tests (IVCT) in patients with a potential MH disposition, provided 376 MH susceptible (MHS), 121 MH equivocal (MHE) and 921 MH negative (MHN) results. Out of these 309 persons had a previous clinical MH event, but for the majority of these persons a real MH disposition could be excluded by the IVCT (197 MHN). In 99 independent MH families, the RYR1 was genetically screened identifying a mutation in 46, whereby 18 different RYR1 point mutations were found of which 4 (Arg401Cys, Ile2182Phe, Gly2375Ala, Ile2453Thr) have not yet been published.

CONCLUSIONS

The disposition to MH may be assessed by the IVCT, DNA analysis and with limitations by the clinical phenotype. The IVCT represents a highly specific method, the DNA analysis appears to be very specific. Under defined conditions an alternative use of the methods is possible. However, these methods should not be regarded as in competition but rather their potential should be complementary or used in specific situations in order to avoid non-detection of MH events in affected families.

Characterization of chromosomal aberrations in a case of glioblastoma multiforme combining cytogenetic and molecular cytogenetic techniques

A case of glioblastoma multiforme (GBM) that was investigated with a broad spectrum of cytogenetic and molecular cytogenetic techniques is reported. The results of cytogenetic studies, interphase fluorescence in situ hybridization, comparative genomic hybridization, and spectral karyotyping (SKY) are reported. Various structural chromosomal aberrations were identified, among which aberrations involving chromosome arm 2p were especially frequent. Using SKY, six translocations not previously described in GBM are reported.

Mutation screening in the ryanodine receptor 1 gene (RYR1) in patients susceptible to malignant hyperthermia who show definite IVCT results: identification of three novel mutations

BACKGROUND

The ryanodine receptor of the skeletal muscle (RYR1) seems to be of outstanding importance in the pathogenesis of malignant hyperthermia (MH). It has been shown that point mutations in the RYR1 gene are strongly associated with the MH phenotype. A correctly determined phenotype is the basic prerequisite for adequate genetic MH screening. In this study we examined only those MH susceptible patients for the presence of potential RYR1 mutations who showed strong pathological muscle responses in the in vitro contracture test (IVCT).

METHODS

A total of 56 MHS index patients who complied with the following IVCT criteria were included in the molecular genetic investigation: Contracture forces > or =4 mN at a caffeine concentration of 2.0 mmol/l and > or =8 mN at a halothane concentration of 0.44 mmol/l. DNA sequences of exons 2, 6, 9, 11, 12, 14, 15, 17, 39, 40, 45, 46, 102 of the RYR1 gene were analysed by the direct sequencing technique. Furthermore, if an MH mutation was identified in an index patient, all relatives were screened for their family specific RYR1 defect.

RESULTS

In 39 index patients an RYR1 mutation was detected: Arg163Cys (n = 2), Asp166Asn (n = 1), Gly341Arg (n = 2), Arg401His (n = 2), Arg614Cys (n = 12), Asp2129Glu (n = 1),Vol2168Met (n = 1), Thr2206Met (n = 9), Ala2428Thr (n = 1), Gly2434Arg (n = 2), Arg2435His (n = 1), Arg2452Trp (n = 1), Arg2454His (n = 4). Three new RYR1 mutations were identified. We found a potential MH mutation in a further 130 relatives of the 39 index patients. Thirty-seven individuals were classified as MHS exclusively by molecular genetic techniques and did not have to undergo the IVCT.

CONCLUSIONS

The ascertained high rate of successful MH mutation screening (69.64%) is obviously associated with the more clearly defined MHS diagnosis in the IVCT. According to the EMHG guidelines for the molecular genetic detection of MH susceptibility, a positive MH disposition could be determined in numerous persons by a less invasive technique.

Homozygous and heterozygous Arg614Cys mutations (1840C-->T) in the ryanodine receptor gene co-segregate with malignant hyperthermia susceptibility in a German family

The determination of susceptibility to malignant hyperthermia (MH) by genetic investigation is a controversial issue because of the genetic heterogeneity of this disorder. The requirement for such an approach in MH diagnosis is a strong correlation between MH-associated genetic abnormalities and phenotypic findings in the in vitro contracture test (IVCT). After a severe clinical MH crisis during general anaesthesia a patient was diagnosed by the IVCT in which susceptibility to MH was confirmed. Genetic screening for MH-related mutations in the RYR1 gene revealed the presence of a homozygous 1840C-->T base exchange (Arg614Cys substitution) in this patient. A specific search for this defect in 20 relatives led to the identification of a total of 11 Arg614Cys mutations. Of these, 10 were heterozygous (including both parents) and one was homozygous (sister). Further IVCTs were subsequently performed on the parents of the index patient, the homozygous sister and all relatives who did not carry the Arg614Cys in order to determine the genotype/phenotype correlation. After analysing these data, and because of the strong correlation between clinical, phenotypic, and genetic results in the index patient, we assigned the diagnosis 'MHS' to all the remaining Arg614Cys mutation carriers of that family without performing the IVCT.

Determination of a positive malignant hyperthermia (MH) disposition without the in vitro contracture test in families carrying the RYR1 Arg614Cys mutation

Molecular genetic methods are used with caution for determining positive malignant hyperthermia (MH) disposition in clinical MH diagnosis because of the genetic variability of this disease. But under defined conditions, genotyping can have an advantage over the standardized in vitro contracture test (IVCT) in respect of invasive approach, specificity, patient compliance, and the work and expense involved in the method. We aim to demonstrate this using 10 families with the Arg614Cys mutation in the ryanodine receptor as an example. Fifty-one index patients who had been classified as MH-susceptible (MHS) in the IVCT (European MH protocol) after a clinical MH incident or suspected MH were screened for the Arg614Cys (C1840-->T) mutation in the RYR1 gene because this mutation is more common in German MH families (9%). The family members of those index patients, in whom a Arg614Cys mutation was detectable, were also screened for the presence of this mutation (n=136), and the results were subjected to a more detailed analysis including existing IVCT findings (n=71). The Arg614Cys mutation was identified in a total of 64 members of the 10 independent families. In 35 individuals in this group, there was a definite concordance between the MHS diagnosis in the IVCT and the presence of the Arg614Cys mutation. No individual phenotyped as MH-negative carried the mutation. On the basis of the guidelines of the EMHG for molecular genetic detection of MH susceptibility, 29 individuals who bore the Arg614Cys mutation were classified as MHS without the IVCT. If a causal mutation is detected in an MH family, the MHS diagnosis can be deduced without the invasive IVCT in all other mutation carriers. Despite inclusion of only one (Arg614Cys) of all known MH mutations, the study emphasizes the practical use of a genetic approach for determination of a positive MH diagnosis.

Maternal isochromosome 7q and paternal isochromosome 7p in a boy with growth retardation

A 12-year 9-month-old boy with postnatal growth retardation, normal psychomotor development, and minor anomalies that included a triangular-shaped face, small nose, and narrow and high-arched palate is reported. The constitutional karyotype was 46,XY,i(7)(p10),i(7)(q10). Molecular investigations revealed the presence of a maternal isodisomy 7q and a paternal isodisomy 7p. The clinical and molecular findings are notably congruent with a recently reported case and support the hypothesis of one or more maternally imprinted genes located on the long arm of chromosomes 7 that regulate, in particular, postnatal growth.

A complex chromosome rearrangement involving chromosome 8, 11, and 12 analyzed by conventional cytogenetic investigations, fluorescence in situ hybridisation, and spectral karyotyping

We report on a 29-year-old woman with a history of five spontaneous abortions and a balanced complex chromosome rearrangement (CCR) involving break points between chromosomes 8, 11, and 12. Fluorescence in situ hybridisation (FISH) in combination with giemsa trypsin banding techniques were essential for the identification of the breakpoints. In addition, the results were confirmed by 24-colour FISH using the spectral karyotyping system (SKY). The karyotype was 46,XX,t(8;11;12)(8qter-->8p10::12p10-->12pter;11pter--> 11q14::8p10-->8pter;12qter-->12p10::11q14-->11qter). Application of SKY facilitated detection of all three chromosomes involved and supported the localisation of the breakpoints by a single time and sample saving investigation.

Genauigkeit pränataler Diagnosen bei terminierten Schwangerschaften - eine retrospektive Analyse der Ergebnisse und Einflussfaktoren1

OBJECTIVE

The aim of the study was to analyse the accuracy of prenatal sonography in terminated pregnancies and the influence of factors like personnel and standard of technique and organisation on the quality of prenatal sonography for the detection of fetal anomalies.

MATERIAL AND METHODS

The retrospective study includes 64 cases with termination of pregnancy from 1989 to 1997. We analyse prenatal sonographic and postnatal pathological findings of fetus, placenta and umbilical cord. Furthermore we compare two time periods (1989-93 and 1994-97) with different ultrasound conditions.

RESULTS

In 36 cases (56%) the prenatal diagnosis was exact. In 7 cases (11%) autopsy could not confirm all findings (false positive), whereas autopsy detected additional anomalies in 18 cases (28%) (false negative). The diagnosis was not correct in 3 cases (5%), whereby 2 pregnancies were terminated without proved somatic and chromosomal anomalies. Compared to 1989-93 the rate of false-positive (12 vs. 5) as well as false-negative (9 vs. 3) diagnoses decreased significantly (p < 0.002) in cases with major anomalies (heart, central nervous system).

CONCLUSION

We conclude that the improvement of the level of organisation, personnel and technical equipment has relevant impact on the accuracy of prenatal sonography. Autopsy as a method of quality control is absolutely necessary.

Mosaic chromosomal aberrations in synovial fibroblasts of patients with rheumatoid arthritis, osteoarthritis, and other inflammatory joint diseases

Chromosomal aberrations were comparatively assessed in nuclei extracted from synovial tissue, primary-culture (P-0) synovial cells, and early-passage synovial fibroblasts (SFB; 98% enrichment; P-1, P-4 [passage 1, passage 4]) from patients with rheumatoid arthritis (RA; n = 21), osteoarthritis (OA; n = 24), and other rheumatic diseases. Peripheral blood lymphocytes (PBL) and skin fibroblasts (FB) (P-1, P-4) from the same patients, as well as SFB from normal joints and patients with joint trauma (JT) (n = 4), were used as controls. Analyses proceeded by standard GTG-banding and interphase centromere fluorescence in situ hybridization. Structural chromosomal aberrations were observed in SFB (P-1 or P-4) from 4 of 21 RA patients (19%), with involvement of chromosome 1 [e.g. del(1)(q12)] in 3 of 4 cases. In 10 of the 21 RA cases (48%), polysomy 7 was observed in P-1 SFB. In addition, aneusomies of chromosomes 4, 6, 8, 9, 12, 18, and Y were present. The percentage of polysomies was increased in P-4. Similar chromosomal aberrations were detected in SFB of OA and spondylarthropathy patients. No aberrations were detected in i) PBL or skin FB from the same patients (except for one OA patient with a karyotype 45,X[10]/46,XX[17] in PBL and variable polysomies in long-term culture skin FB); or ii) synovial tissue and/or P-1 SFB of normal joints or of patients with joint trauma. In conclusion, qualitatively comparable chromosomal aberrations were observed in synovial tissue and early-passage SFB of patients with RA, OA, and other inflammatory joint diseases. Thus, although of possible functional relevance for the pathologic role of SFB in RA, these alterations probably reflect a common response to chronic inflammatory stress in rheumatic diseases.

Prenatal diagnosis of del(15)(q26.1) and del(18)(q21.3) due to an unbalanced de novo translocation: ultrasound, molecular cytogenetic and autopsy findings

A case of partial deletion of the distal parts of chromosomes 15 and 18 [(15)(q26.1)(18)(q21.3)] due to a de novo translocation is reported. Cordocentesis and fetal karyotyping was done because of severe oligohydramnios and bilateral absence of kidneys. Renal defects are a frequent finding in fetuses with different chromosomal anomalies; this particular chromosomal rearrangement however has not been reported yet in a fetus with bilateral renal agenesis. FISH was performed for detailed clarification of the chromosomal anomaly. Prenatal karyotyping appears to be important in fetuses with renal agenesis.

De novo complete trisomy 5p: clinical report and FISH studies

We describe a de novo trisomy 5p in a 1-year-old severely retarded boy. The complete short arm of chromosome 5 segregated as an additional marker chromosome in all metaphases. The marker was identified as 5p by conventional cytogenetic techniques (GTG, GBG, CBG) and molecular cytogenetic techniques (whole chromosome-painting probe, probes for the cri-du-chat region and the centromere, and additionally high-resolution multicolor banding using a chromosome 5-specific DNA probe cocktail). The clinical findings were similar to the established trisomy 5p phenotype including macrocephaly, facial abnormalities, tracheobronchial defects with subsequent respiratory infections, hypotonia, and psychomotor retardation. To the best of our knowledge this is the first description of an isolated complete 5p trisomy without involvement of the aberrant chromosome in any structural chromosomal rearrangements.

Prenatal detection of a giant bilateral thoracic vascular lesion: prognostic evaluation and genetic aspects

We describe a giant bilateral vascular mass in the skin of the chest diagnosed by ultrasound investigation in a fetus of 20 gestational weeks. Ultrasound and colour Doppler investigations detected no signs of early congestive heart failure but rapid and excessive enlargement of the vascular mass. Indications of increased fetal blood volume were found. The fetus had additional minor anomalies. Early in utero manifestation suggests a severe vascular malformation.

Pitfalls in prenatal diagnosis of DMD due to placental mosaicism of the X-chromosomes: prenatal and postnatal findings in a fetus with a deletion of exons 67-71 of the dystrophin gene

Prenatal diagnosis of Duchenne and Becker muscular dystrophy (DMD) is performed as a routine procedure in many laboratories. The major potential problem is an incorrect diagnosis that could be obtained due to contamination with maternal tissue. We report a case of mosaicism of the X-chromosomes confined to the placenta as a possible source of confusing results in prenatal diagnosis of DMD. To the best of our knowledge, this is the first reported case of this problem in a prenatal DMD diagnosis.

Microcephaly-lymphedema syndrome: report of a family with short stature as additional manifestation

Patients with the rare autosomal dominant microcephaly-lymphedema syndrome have apparently normal intelligence. We report on a boy with microcephaly, lymphedema, and short stature as an additional manifestation. The family history of our patient suggests autosomal dominant inheritance with reduced penetrance and variable expressivity. However, X-linked inheritance cannot be excluded.

Lethal multiple pterygium syndrome: suggestion for a consistent pathological workup and review of reported cases

We report on 2 brothers with lethal multiple pterygium syndrome (LMPS) born to non-consanguineous parents as late spontaneous abortions. Both fetuses presented with massive nuchal edema, and facial anomalies including cleft palate and broad ribs. Apparently, several subgroups of LMPS exist. Differentiation is difficult, as there is no consistent agreement on a workup protocol for autopsies. We compared the findings in the literature on cases with LMPS, and we suggest a standardized workup as an initial step for more efficient differentiation between various subgroups.

Bilateral brachial amelia, facial clefts, encephalocele, orbital cyst and omphalocele: a recurrent fetal malformation pattern coming into focus

Ultrasonographic and pathoanatomical features of a fetus displaying bilateral brachial amelia, complex facial clefting, encephalocele and omphalocele are described. The findings are compared with the few previously published cases. Bilateral brachial amelia with complex other organ malformations in previable fetuses may be more frequently diagnosed with improving prenatal ultrasonography.

VACTERL with hydrocephalus and branchial arch defects: prenatal, clinical, and autopsy findings in two brothers

VACTERL association is defined as a combination of vertebral, anal, cardiac, tracheoesophageal, renal and limb anomalies, in particular radial defects. In recent years hydrocephalus was observed in patients with apparent VACTERL association. This particular condition was recognized as a hereditary entity with poor prognosis. Both autosomal recessive and X-linked forms were described. Here we report prenatal, clinical and autopsy findings in 2 brothers with this syndrome, who had, in addition, branchial arch anomalies. The recurrence in this family suggests X-linked inheritance. Branchial arch defects have so far not been described as part of the VACTERL+H syndrome. This observation further supports that a variety of brain anomalies including hydrocephalus associated with VACTERL anomalies represents separate entities with a considerable recurrence risk. The use of the term VACTERL "association" for these conditions is misleading and is discouraged.

Diaphragmatic defects, limb deficiencies, and ossification defects of the skull: a distinctive malformation syndrome

We report on prenatal and postnatal findings in 4 consecutive fetuses with a pattern of severe congenital anomalies who were born to a healthy nonconsanguineous couple. The spectrum of malformations includes diaphragmatic defects, hypoplastic lungs, omphalocele, limb deficiencies, syndactyly of toes, and ossification defects of the skull. This specific spectrum of anomalies is not fully compatible with that of any established syndrome. No prenatal exposure to any possible teratogen was found. Family history is suggestive for autosomal recessive inheritance, even though germ-line mosaicism in one of the parents cannot completely be excluded.

Limb defects and chorionic villus sampling: results from an international registry, 1992-94

BACKGROUND

Several reports of limb defects occurring among infants exposed to chorionic villus sampling (CVS) during pregnancy resulted in concern about the safety of this procedure for prenatal diagnosis. To avoid publication bias and evaluate the true risk of limb defects in a CVS cohort, the World Health Organization initiated international registration of post-CVS limb defects in 1992.

METHODS

From May, 1992, to May, 1994, 77 infants or fetuses with limb defects from 138 996 pregnancies having CVS were reported to the WHO CVS Registry. These cases were analysed by standardised methods-ie, exclusion of syndromes, inherited disorders, and defects occurring in previable fetuses. The included limb deficiencies were studied by pattern analysis.

FINDINGS

Defects of the upper limbs were reported in 64.6%, of the lower limbs in 12.5%, and of both upper and lower limbs in 20.8% of cases. These figures are in agreement with the distribution of limb defects in several large population-based studies. Transverse limb defects occurred in 40.8% and longitudinal defects in 59.2%, compared with 42.7% and 57.3% in an unexposed population.

INTERPRETATION

The analysis of this cohort did not show any differences from the background population in the overall frequency or pattern distribution of limb deficiencies. There was also no correlation between gestational age at CVS and severity of defects. Therefore these results do not indicate any increased risk of limb defects after CVS.

[Fragile X syndrome: clinical and molecular genetics correlations]

The fragile X form of mental retardation is presently recognized as the most frequent hereditable cause of mental impairment. The estimated frequency among males is 1 in 1250, and 1 in 2000 among females. Beside mental impairment and behavioural disturbance with hyperactivity and autistic features, the patients are characterized by morphological anomalies, such as an oblong face, broad, rectangular chin, large protruding ears and macro-orchidism. A less severe clinical expression can be found among females heterozygotes of the disorder, manifesting mainly as learning disability. The disorder is associated with the expression of a fragile site at Xq27.3 under conditions of folate depletion in the chromosome culture medium. The molecular mechanism is based on the expansion of a trinucleotide repeat [CCG]n in the promoter region of the FMR1 gene resulting in methylation of the gene. The trinucleotide repeat shows variable lengths of 6 to 53 repeats in the general population, 60 to 200 repeats in carriers of a premutation and over 200 repeats in patients with fragile X syndrome.

[Genetic risks of in vitro fertilization]

In-vitro fertilization (IVF) with embryo transfer is a well established therapy in infertility. With the increase of andrological problems as reasons for IVF the question of possible genetic risks is gaining additional attention. For the patients, the incidence of congenital malformations in their offspring resulting from IVF as well as the incidence of spontaneous abortions are of particular interest. In this review population genetic data of congenital malformations are compared to those found in IVF populations. On average, congenital malformations occur in 3% of all livebirths in an unselected population, whereas there were 1.5% newborns with congenital malformations reported in the IVF population. This is well within this basic background risk for congenital malformations. Bearing maternal age and especially careful follow-up of early pregnancies after IVF in mind, the rate of spontaneous abortions after IVF (21 to 27%) is also not significantly increased above the rate of 15% in the unselected general population. The introduction of microinvasive techniques into IVF has given the question of possible genetic risks for the offspring from IVF using these techniques, a great deal of topical interest. The range of indications of subzonal or intracytoplasmatic sperm injection (ICSI) includes andrological problems to a high degree which themselves could be the result of chromosomal anomalies or hereditary disorders. One example is the vas deferens aplasia in one form of CF mutations. Cytogenetic and clinical genetic evaluation should be recommended especially in cases of andrological or idiopathic sterility and infertility. Some examples of autosomal dominant syndromes in which clinical genetic evaluation and genetic counselling are advisable are listed in a summarizing table.

Familial pericentric inversion of chromosome 1 (p34q23) and male infertility with stage specific spermatogenic arrest

We report on two infertile brothers presenting with severe oligozoospermia or azoospermia. Testicular biopsy was performed on one of them and showed spermatogenic arrest at the level of primary spermatocytes. Both brothers were found to be heterozygous for a pericentric inversion of chromosome 1 (46,XY,inv(1)(p34q23)). The inversion chromosome was inherited through the maternal line, with no indication of subfertility in the probands' mother.