Methylation of the 4q35 D4Z4 repeat defines disease status in facioscapulohumeral muscular dystrophy.

Genetic diagnosis of facioscapulohumeral muscular dystrophy (FSHD) remains a challenge in clinical practice as it cannot be detected by standard sequencing methods despite being the third most common muscular dystrophy. The conventional diagnostic strategy addresses the known genetic parameters of FSHD: the required presence of a permissive haplotype, a size reduction of the D4Z4 repeat of chromosome 4q35 (defining FSHD1) or a pathogenic variant in an epigenetic suppressor gene (consistent with FSHD2). Incomplete penetrance and epistatic effects of the underlying genetic parameters as well as epigenetic parameters (D4Z4 methylation) pose challenges to diagnostic accuracy and hinder prediction of clinical severity. In order to circumvent the known limitations of conventional diagnostics and to complement genetic parameters with epigenetic ones, we developed and validated a multistage diagnostic workflow that consists of a haplotype analysis and a high-throughput methylation profile analysis (FSHD-MPA). FSHD-MPA determines the average global methylation level of the D4Z4 repeat array as well as the regional methylation of the most distal repeat unit by combining bisulphite conversion with next-generation sequencing and a bioinformatics pipeline and uses these as diagnostic parameters. We applied the diagnostic workflow to a cohort of 148 patients and compared the epigenetic parameters based on FSHD-MPA to genetic parameters of conventional genetic testing. In addition, we studied the correlation of repeat length and methylation level within the most distal repeat unit with age-corrected clinical severity and age at disease onset in FSHD patients. The results of our study show that FSHD-MPA is a powerful tool to accurately determine the epigenetic parameters of FSHD, allowing discrimination between FSHD patients and healthy individuals, while simultaneously distinguishing FSHD1 and FSHD2. The strong correlation between methylation level and clinical severity indicates that the methylation level determined by FSHD-MPA accounts for differences in disease severity among individuals with similar genetic parameters. Thus, our findings further confirm that epigenetic parameters rather than genetic parameters represent FSHD disease status and may serve as a valuable biomarker for disease status.

Basal ganglia pathology in ALS is associated with neuropsychological deficits.

OBJECTIVES: To evaluate basal ganglia changes along the amyotrophic lateral sclerosis (ALS)-ALS-frontotemporal dementia (FTD) continuum using multiple, complementary imaging techniques. METHODS: Sixty-seven C9orf72-negative patients with ALS and 39 healthy controls were included in a cross-sectional quantitative MRI study. Seven patients with ALS met criteria for comorbid behavioral variant FTD (ALS-FTD), 18 patients met the Strong criteria for cognitive and/or behavioral impairment (ALS-Plus), and 42 patients had no cognitive impairment (ALS-Nci). Volumetric, shape, and density analyses were performed for the thalamus, amygdala, nucleus accumbens, hippocampus, caudate nucleus, pallidum, and putamen. RESULTS: Significant basal ganglia volume differences were identified between the study groups. Shape analysis revealed distinct atrophy patterns in the amygdala in patients with ALS-Nci and in the hippocampus in patients with ALS-Plus in comparison with controls. Patients with ALS-FTD exhibited pathologic changes in the bilateral thalami, putamina, pallida, hippocampi, caudate, and accumbens nuclei in comparison with all other study groups. A preferential vulnerability has been identified within basal ganglia subregions, which connect directly to key cortical sites of ALS pathology. While the anatomical patterns were analogous, the degree of volumetric, shape, and density changes confirmed incremental pathology through the spectrum of ALS-Nci, ALS-Plus, to ALS-FTD. Performance on verbal memory tests correlated with hippocampal volumes, and accumbens nuclei volumes showed a negative correlation with apathy scores. CONCLUSIONS: We demonstrate correlations between basal ganglia measures and structure-specific neuropsychological performance and a gradient of incremental basal ganglia pathology across the ALS-ALS-FTD spectrum, suggesting that the degree of subcortical gray matter pathology in C9orf72-negative ALS is closely associated with neuropsychological changes.

Intermittent pre-excitation-syndrome in facio-scapulo-humeral muscular dystrophy.

Pre-excitation-syndrome has not been reported as a phenotypic feature of facio-scapulo-humeral muscular dystrophy (FSH-MD). In a 39-year-old male with FSH-MD due to a reduced tandem repeat size in the D4Z4-locus on chromosome 4q35, cardiac involvement, manifesting as an incomplete right bundle-branch-block, tall T-waves in V 3-5, ST-elevation in V 2-4, and mild thickening of the left ventricular myocardium, was first recognised 10 years earlier. Follow-up at age 39 years revealed mild myocardial thickening, two intra-ventricular aberrant bands, and, surprisingly, intermittent pre-excitation on a routine electrocardiography. Cardiac involvement in FSH-MD may manifest as hypertrophic cardiomyopathy or various arrhythmias, of which one may be pre-excitation-syndrome.

Long-term persistence and effects of fetal microchimerisms on disease onset and status in a cohort of women with rheumatoid arthritis and systemic lupus erythematosus.

BACKGROUND: The discovery of a fetal cells transfer to the mother is a phenomenon with multiple implications for autoimmunity and tolerance. The prevalence and meaning of the feto-maternal microchimerism (MC) in rheumatic diseases has not been thoroughly investigated. The aim of this study was to analyze the prevalence of fetal MC in patients with inflammatory rheumatic diseases and to investigate the association of MC with disease onset and current status. METHODS: A total of 142 women who gave birth to at least one male offspring were recruited: 72 women with rheumatoid arthritis (RA), 16 women with systemic lupus erythematosus (SLE), and 54 healthy women. For the detection of fetal microchimerism a nested PCR method was used to amplify a Y chromosome specific sequence (TSPY1). For characterization of disease activity we analyzed autoantibody profiles and X-rays in RA, and in addition complement levels in SLE respectively. RESULTS: A significant higher prevalence of fetal MC was found in RA (18%) and SLE (31%) compared to controls (3.7%) (p = 0.02 and p = 0.006, resp.). The mean age at disease onset was comparable in MC + and MC- RA patients. Disease onset occurred 18.7 (MC +) and 19.8 (MC-) years post partum of the first son, respectively. The presence of anti-CCP and RF did not differ significantly, anti-CCP were found in 75% of MC + and 87% of MC- patients, RF in 75% of both MC + and MC- patients. A slightly higher mean Steinbrocker score in MC + patients was associated with longer disease duration in MC + compared to MC- RA. In SLE patients the mean age at disease onset was 42.6 years in MC + and 49.1 years in MC- patients. Disease onset occurred 24.0 and 26.4 years post partum of the first son for MC + and MC- patients, respectively. The presence of ANA and anti-dsDNA antibodies, C3, C4 and CH50 did not differ significantly. CONCLUSION: Our results indicate a higher frequency of long-term male MC in RA and SLE patients compared with controls without impact on disease onset and status in RA and SLE.

Sonography of the median nerve in CMT1A, CMT2A, CMTX, and HNPP.

INTRODUCTION: In this study we compare the ultrasound features in the median nerve in patients with different types of Charcot-Marie-Tooth (CMT) disease and hereditary neuropathies with liability to pressure palsies (HNPP) as a typical entrapment neuropathy. METHODS: Median nerve ultrasound and conduction studies were performed in patients with CMT1A (n = 12), MFN2-associated CMT2A (n = 7), CMTX (n = 5), and HNPP (n = 5), and in controls (n = 28). RESULTS: Median nerve cross-sectional area (CSA) was significantly increased in CMT1A, whereas, in axonal CMT2A, fascicle diameter (FD) was enlarged. CSA correlated with nerve conduction slowing in CMT1A and with axonal loss, as shown by motor and sensory nerve amplitudes in both CMT1A and CMT2A. A relatively low wrist-to-forearm-ratio (WFR <0.8) or a relatively high WFR (>1.8) appeared to be unlikely in MFN2 and Cx32 mutations of CMT2A and CMTX, respectively. CONCLUSION: Differences in CSA, FD, and WFR of the median nerve can be helpful in defining subtypes of hereditary neuropathies.

Neonatal progeria: increased ratio of progerin to lamin A leads to progeria of the newborn.

Hutchinson-Gilford progeria syndrome (HGPS) is an important model disease for premature ageing. Affected children appear healthy at birth, but develop the first symptoms during their first year of life. They die at an average age of 13 years, mostly because of myocardial infarction or stroke. Classical progeria is caused by the heterozygous point mutation c.1824C>T in the LMNA gene, which activates a cryptic splice site. The affected protein cannot be processed correctly to mature lamin A, but is modified into a farnesylated protein truncated by 50 amino acids (progerin). Three more variations in LMNA result in the same mutant protein, but different grades of disease severity. We describe a patient with the heterozygous LMNA mutation c.1821G>A, leading to neonatal progeria with death in the first year of life. Intracellular lamin A was downregulated in the patient's fibroblasts and the ratio of progerin to lamin A was increased when compared with HGPS. It is suggestive that the ratio of farnesylated protein to mature lamin A determines the disease severity in progeria.

Haplotypes in the UGT1A1 gene and their role as genetic determinants of bilirubin concentration in healthy German volunteers.

BACKGROUND: Genetic variations of UDP-glucuronyltransferase 1A1 (UGT1A1) influence the concentration of serum bilirubin. We investigated the association of four common polymorphisms including UGT1A1-53(TA)(n), and common haplotypes of the UGT1A1 gene with bilirubin levels in 218 Caucasian volunteers. METHODS: Total bilirubin was measured in serum of 218 healthy Caucasian volunteers. Genotyping of four genetic variants was performed: UGT1A1-53(TA)(6/7), UGT1A1c.-3279T>G, UGT1A1c.-3156G>A, and UGT1A1c.211G>A. The association between polymorphisms/haplotypes and bilirubin levels were determined. RESULTS: Minor allele frequencies were 0.36 for UGT1A1-53(TA)(7), 0.47 for c.-3279G, 0.33 for c.-3156A and 0.006 for c.211A. The three promoter polymorphisms were in close linkage disequilibrium. Common haplotypes were: -53(TA)(6)/c.-3279T/c.211G (frequency 0.530), -53(TA)(7)/c.-3279G/c.211G (frequency 0.365), and -53(TA)(6)/c.-3279G/c.211G (frequency 0.099). Male sex, UGT1A1-53(TA)(6/7) and the c.-3279GG variant were significantly associated with higher bilirubin concentrations. CONCLUSIONS: Two UGT1A1 promoter polymorphisms (-53(TA)(6/7) and c.-3279T>G) and a common haplotype of the UGT1A1 gene are associated with serum bilirubin concentrations in Caucasians.

The heterozygous LMNA mutation p.R471G causes a variable phenotype with features of two types of familial partial lipodystrophy.

We report on a novel LMNA mutation (p.R471G) in a proband affected by a syndrome comprising partial lipodystrophy, insulin-resistant diabetes, acanthosis nigricans, liver steatosis, muscle weakness, and contractures. This phenotype has features of both types 1 and 2 familial partial lipodystrophy. The sister and father of the proband had the same mutation. The sister was more mildly affected and the father was apparently unaffected, demonstrating variable expressivity and reduced penetrance for this mutation.

Tandem duplication of DMD exon 18 associated with epilepsy, macroglossia, and endocrinologic abnormalities.

We describe a patient with Duchenne muscular dystrophy (DMD) who additionally suffered from intractable seizures, severe mental retardation, and a marked macroglossia. He also had endocrinologic abnormalities consisting of growth hormone deficiency, delayed puberty, and adrenal hypoplasia. We detected a duplication of DMD exon 18 and flanking introns that caused a frame-shift and was not removed by corrective splicing. A coincident mutation in the FKRP gene was excluded by direct sequencing. Complex DNA rearrangements, deletions, and duplications >100 kb were excluded through microarray-comparative genomic hybridization (CGH), although we were not able to exclude a second coincident mutation with certainty. In conclusion, we present a case of DMD that conflicts with current understanding of genotype-phenotype relations and discuss putative pathogenetic mechanisms for this uncommon phenotype.

Symptoms of OTC deficiency but not DMD in a female carrier of an Xp21.1 deletion including the genes for dystrophin and OTC.

A contiguous deletion encompassing the genes for dystrophin, cytochrome b(-245) beta-subunit (CYBB), retinitis pigmentosa GTPase regulator (RPGR), and OTC was detected in a female patient only suffering from OTC deficiency while symptoms of the other conditions were not present.

Intrachromosomal triplication 12p11.22-p12.3 and gonadal mosaicism of partial tetrasomy 12p.

Cases of tetrasomy 12p and trisomy 12p are known to be associated with specific phenotypic abnormalities well described in the literature. Here, we report on the unusual case of a partial tetrasomy 12p found in an affected patient and in a mosaic constellation in the patient's mother, who showed no phenotypic abnormality. The index patient was a 16-year-old boy with clinical features similar to the "trisomy 12p syndrome" including mental retardation, macrocephaly, a short nose with anteverted nostrils, and a broad protruding lower lip. G-banding analysis and fluorescence in situ hybridization (FISH) experiments using locus specific YAC DNA probes revealed a derivative chromosome 12 with a partial triplication of the short arm with an inverted copy, flanked by two direct copies. Chromosome analyses in parental lymphocytes showed a chromosomal mosaicism in the phenotypically normal mother, with 12% cells exhibiting the same partial tetrasomy 12p as detected in her son. The allelic pattern of short tandem repeats (STR) in the mother's blood DNA showed that a chimerism can be excluded with high probability. To our knowledge, this is the first report of intrachromosomal triplication on chromosome 12, as well as partial tetrasomy 12p mosaicism. Moreover, as a consequence of the chromosomal aberration in the son it can be concluded that a gonadal mosaicism is present in the mother.

Brain 1H magnetic resonance spectroscopic differences in myotonic dystrophy type 2 and type 1.

To evaluate cerebral metabolism and intergroup differences in closely matched patients with myotonic dystrophy type 2 (DM2, n = 15) and type 1 (DM1, n = 14), we performed (1)H magnetic resonance spectroscopic (MRS) analyses of the occipital and temporoparietal cortical regions as well as of subcortical frontal white matter. Relative to healthy subjects, the concentration of N-acetylaspartate was significantly reduced in all tested brain regions in both disease groups. In the DM1 patients we also observed a concomitant depletion of creatine and choline levels, particularly in the frontal white matter. A discriminant analysis based on the (1)H-MRS data distinguished between the DM2, DM1, and control groups with an overall accuracy of 88%. (1)H-MRS indicates that neurochemical alterations involving gray and white matter occur in patients with DM2 and DM1. Although structural abnormalities (cerebral atrophy, white matter lesions) are similar in DM2 and DM1, changes in cerebral metabolites can differentiate these disease groups, suggesting that the diseases differ in their neurocellular pathology.

Identification of Alu elements mediating a partial PMP22 deletion.

Hereditary neuropathy with liability to pressure palsies (HNPP) is most frequently caused by deletion of a 1.4-Mb region in chromosome 17p11.2-12 including the peripheral myelin protein 22 (PMP22) gene. Smaller deletions partially affecting the PMP22 gene are less frequently observed. We identified in a HNPP patient a deletion of the 5' region of PMP22 including non-coding exon 1, coding exons 2 and 3, whereas, exons 4 and 5 were present. PMP22 exon 3- and 4-specific qPCR resulted in a deletion of one exon 3 allele but in the presence of 2 exon 4 alleles. SNP analysis revealed the presence of heterozygosity for PMP22 coding exons 4 and 5. Finally, MLPA specific for the CMT1A region defined this deletion for the entire 5' region of PMP22 (exons 1, 2 and 3). These partial HNPP deletions may be missed by other techniques, e.g., STR marker analysis. Alu elements have been reported to mediate non-allelic recombination events. Bioinformatic analysis revealed 12 Alu elements flanking in close neighbourhood the estimated 40-kb deletion region as candidates for recombination events. PCR primers were designed to identify a breakpoint-spanning product including the respective Alu elements. PCR-driven identification of a junction fragment was successful with AluJo-AluSq and AluYb9-AluSq specific primer pairs comprising the same intronic region of PMP22. Sequence analysis of these breakpoint-overlapping PCR fragments revealed a 29-bp motif including a chi-like sequence (GCTGG) present both in the AluYb9 and the AluSq element. These data confirm that low-copy repeats (LCRs) mediate non-allelic homologous recombinations (NAHR).

Mice lacking the nuclear pore complex protein ALADIN show female infertility but fail to develop a phenotype resembling human triple A syndrome.

Triple A syndrome is a human autosomal recessive disorder characterized by adrenal insufficiency, achalasia, alacrima, and neurological abnormalities affecting the central, peripheral, and autonomic nervous systems. In humans, this disease is caused by mutations in the AAAS gene, which encodes ALADIN, a protein that belongs to the family of WD-repeat proteins and localizes to nuclear pore complexes. To analyze the function of the gene in the context of the whole organism and in an attempt to obtain an animal model for human triple A syndrome, we generated mice lacking a functional Aaas gene. The Aaas-/- animals were found to be externally indistinguishable from their wild-type littermates, although their body weight was on the average lower than that of wild-type mice. Histological analysis of various tissues failed to reveal any differences between Aaas-/- and wild-type mice. Aaas-/- mice exhibit unexpectedly mild abnormal behavior and only minor neurological deficits. Our data show that the lack of ALADIN in mice does not lead to a triple A syndrome-like disease. Thus, in mice either the function of ALADIN differs from that in humans, its loss can be readily compensated for, or additional factors, such as environmental conditions or genetic modifiers, contribute to the disease.

Increased frequency of cystic fibrosis transmembrane conductance regulator gene mutations in infertile males.

OBJECTIVE: To investigate the frequency of mutations of the cystic fibrosis transmembrane regulator (CFTR) gene in males with reduced sperm quality before intracytoplasmic sperm injection (ICSI). DESIGN: The nine most frequent cystic-fibrosis-causing mutations in the German population and IVS8T alleles were analyzed. SETTING: University-based centers for reproductive medicine and clinical genetics. PATIENT(S): An unselected group of 597 males with oligo-, astheno-, terato-, crypto-, oligoasthenoteratozoospermia, or azoospermia, which underwent pre-ICSI genetic counseling over a 5-year period. INTERVENTION(S): Blood samples were collected from the patients during genetic counseling. MAIN OUTCOME MEASURE(S): Frequency of mutations of CFTR gene in infertile males. RESULT(S): A heterozygous CFTR mutation was observed in 34 of 597 patients (5.70%). None of the patients had two CFTR mutations. Given that our mutation panel recognizes about 82% of heterozygotes, it can be assumed that the frequency of CFTR heterozygotes in our cohort is about 6.94%. The frequency of CFTR mutations in our cohort did not correlate with a reduced sperm count. CONCLUSION(S): The frequency of cystic fibrosis in the German population is 1:3300. Thus, a CFTR heterozygosity of 3.42% can be estimated. This indicates that in our cohort of infertile males, the frequency of CFTR heterozygosity is twofold higher than in the general population (P<.0001).

Homozygous microdeletion of chromosome 4q11-q12 causes severe limb-girdle muscular dystrophy type 2E with joint hyperlaxity and contractures.

Microdeletion syndromes are commonly transmitted as dominant traits and are frequently associated with variably expressed pleiotropic phenotypes. Nonlethal homozygous microdeletions, on the other hand, are very rare. Here, we delineate the fifth and so far largest homozygous microdeletion in nonmalignancies of approximately 400 kb on chromosome 4q11-q12 in a large consanguineous East-Anatolian family with six affected patients. The deleted region contains the beta-sarcoglycan gene (SGCB), the predicted gene SPATA18 (spermatogenesis associated 18 homolog) and several expressed sequence tags. Patients presented with a severe and progressive Duchenne-like muscular dystrophy phenotype, a combination of hyperlaxity and joint contractures, chest pain, palpitations, and dyspnea.

Twenty-six novel EFNB1 mutations in familial and sporadic craniofrontonasal syndrome (CFNS).

Craniofrontonasal syndrome (CFNS) is an X-linked disorder characterized by a more severe manifestation in heterozygous females than in hemizygous males. Heterozygous females have craniofrontonasal dysplasia (CFND) and occasionally extracranial manifestations including midline defects and skeletal abnormalities, whereas hemizygous males show no or only mild features such as hypertelorism and rarely show cleft lip or palate. Mutations in the EFNB1 gene in Xq12 are responsible for familial and sporadic CFNS. The EFNB1 gene encodes ephrin-B1, a transmembrane ligand that also exhibits receptor-like effects. We performed mutation analysis in nine unrelated families and 29 sporadic patients with CFNS. DNA sequencing revealed mutations in 33 (86.8%) cases including 26 distinct novel mutations. A recurrent nonsense mutation, c.196C>T/R66X, was detected in one family and four sporadic patients. The majority of mutations (26/33) were located in exons 2 and 3 of the EFNB1 gene encoding the extracellular ephrin domain. The mutation spectrum includes frameshift, nonsense, missense, and splice site mutations, with a predominance of frameshift and nonsense mutations resulting in premature truncation codons. For the first time we describe mutations in exons 4 and 5 of EFNB1. Of particular interest are the frameshift mutations located in the last 25 codons of EFNB1 encoding the carboxyterminal end of ephrin-B1. They result in an extension by 44 residues. These mutations disrupt the intracellular binding sites for Grb4 and PDZ-effector proteins involved in reverse signaling. We conclude that the major causes of familial as well as sporadic CFNS are loss of function mutations in the EFNB1 gene that comprise premature termination or abrogate receptor-ligand interaction, oligomerization, and ephrin-B1 reverse signaling.

Novel and recurrent mutations in patients with androgen insensitivity syndromes.

BACKGROUND/AIMS: Androgen insensitivity syndrome (AIS) caused by mutations within the androgen receptor gene represents a variety of phenotypes from females with 46,XY karyotype over individuals with ambiguous genitalia to infertile males. METHODS: We studied 24 patients with AIS by sequencing androgen receptor gene. 19 of the investigated patients were affected by complete androgen insensitivity syndrome (CAIS) and 5 suffered from partial androgen insensitivity syndrome (PAIS). RESULTS: So far we have detected 12 unreported mutations as well as 9 recurrent mutations (3 recurrent mutations were detected twice) in exons 2-8 of the androgen receptor gene. Three of the novel mutations cause a frameshift with subsequent premature termination and were found in patients with CAIS. These frameshifts were induced by single nucleotide deletion or insertion, or in one case by a 13-bp deletion, respectively. Another premature stop codon found in a CAIS patient results from an already reported nucleotide substitution in exon 5. Furthermore, in a CAIS patient we found a novel duplication of codon 788. All other mutations caused single base substitutions spread through exons 2-8 and were associated with CAIS or PAIS. CONCLUSIONS: We report a broad spectrum of different mutations within the AR gene leading to various manifestations of AIS. Apart from truncating mutations, a reliable genotype/phenotype correlation cannot be established. Therefore, modifying factors must be effective.

Mutations of the ephrin-B1 gene cause craniofrontonasal syndrome.

Craniofrontonasal syndrome (CFNS) is an X-linked craniofacial disorder with an unusual manifestation pattern, in which affected females show multiple skeletal malformations, whereas the genetic defect causes no or only mild abnormalities in male carriers. Recently, we have mapped a gene for CFNS in the pericentromeric region of the X chromosome that contains the EFNB1 gene, which encodes the ephrin-B1 ligand for Eph receptors. Since Efnb1 mutant mice display a spectrum of malformations and an unusual inheritance reminiscent of CFNS, we analyzed the EFNB1 gene in three families with CFNS. In one family, a deletion of exons 2-5 was identified in an obligate carrier male, his mildly affected brother, and in the affected females. In the two other families, missense mutations in EFNB1 were detected that lead to amino acid exchanges P54L and T111I. Both mutations are located in multimerization and receptor-interaction motifs found within the ephrin-B1 extracellular domain. In all cases, mutations were found consistently in obligate male carriers, clinically affected males, and affected heterozygous females. We conclude that mutations in EFNB1 cause CFNS.

Improvement of the diagnostic procedure in proximal myotonic myopathy/myotonic dystrophy type 2.

Proximal myotonic myopathy/myotonic dystrophy type 2 (PROMM/DM 2) is caused by an expansion of the (TG)n(TCTG)n(CCTG)n repeat tract in intron 1 of the ZNF9 gene located on chromosome 3q21. Because these expansions show a marked mitotic instability, expanded alleles are often difficult to detect. In order to improve the diagnostic procedure, we applied a combination of pulsed-field gel electrophoresis and semi-quantitative Southern blot analysis with a novel hybridization probe. The combination of these methods led to unequivocal results in about 98% of cases with a clinical diagnosis of PROMM/DM 2. Furthermore, we report the genotype/phenotype correlation in a patient lacking a normal ZNF9 allele and a further proband with a "grey zone" allele.