Ataxia-Pancytopenia Syndrome Is Caused by Missense Mutations in SAMD9L.

Ataxia-pancytopenia (AP) syndrome is characterized by cerebellar ataxia, variable hematologic cytopenias, and predisposition to marrow failure and myeloid leukemia, sometimes associated with monosomy 7. Here, in the four-generation family UW-AP, linkage analysis revealed four regions that provided the maximal LOD scores possible, one of which was in a commonly microdeleted chromosome 7q region. Exome sequencing identified a missense mutation (c.2640C>A, p.His880Gln) in the sterile alpha motif domain containing 9-like gene (SAMD9L) that completely cosegregated with disease. By targeted sequencing of SAMD9L, we subsequently identified a different missense mutation (c.3587G>C, p.Cys1196Ser) in affected members of the first described family with AP syndrome, Li-AP. Neither variant is reported in the public databases, both affect highly conserved amino acid residues, and both are predicted to be damaging. With time in culture, lymphoblastic cell lines (LCLs) from two affected individuals in family UW-AP exhibited copy-neutral loss of heterozygosity for large portions of the long arm of chromosome 7, resulting in retention of only the wild-type SAMD9L allele. Newly established LCLs from both individuals demonstrated the same phenomenon. In addition, targeted capture and sequencing of SAMD9L in uncultured blood DNA from both individuals showed bias toward the wild-type allele. These observations indicate in vivo hematopoietic mosaicism. The hematopoietic cytopenias that characterize AP syndrome and the selective advantage for clones that have lost the mutant allele support the postulated role of SAMD9L in the regulation of cell proliferation. Furthermore, we show that AP syndrome is distinct from the dyskeratoses congenita telomeropathies, with which it shares some clinical characteristics.

An 8-generation family with X-linked Charcot-Marie-Tooth: Confirmation Of the pathogenicity Of a 3' untranslated region mutation in GJB1 and its clinical features.

INTRODUCTION: Mutations in gap junction protein beta 1 (GJB1) on the X chromosome represent one of the most common causes of hereditary neuropathy. We assessed manifestations associated with a rare 3' untranslated region mutation (UTR) of GJB1 in a large family with X-linked Charcot-Marie-Tooth disease (CMTX). METHODS: Clinical, electrophysiological, and molecular genetic analyses were performed on an 8-generation family with CMTX. RESULTS: There were 22 affected males and 19 symptomatic females, including an 83-year-old woman followed for 40 years. Electrophysiological studies showed a primarily axonal neuropathy. The c.*15C>T mutation in the GJB1 3' UTR was identified in 4 branches of the family with a log of odds (LOD) of 4.91. This created a BstE II enzyme recognition site that enabled detection by restriction digestion. DISCUSSION: The c.*15C>T mutation in the GJB1 3' UTR segregates with CMTX1 in 8 generations. Penetrance in males and females is essentially complete. A straightforward genetic method to detect this mutation is described. Muscle Nerve 57: 859-862, 2018.

Two novel mutations in ABHD12: expansion of the mutation spectrum in PHARC and assessment of their functional effects.

PHARC (polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataracts) is a recently described autosomal-recessive neurodegenerative disease caused by mutations in the α-ß-hydrolase domain-containing 12 gene (ABHD12). Only five homozygous ABHD12 mutations have been reported and the pathogenesis of PHARC remains unclear. We evaluated a woman who manifested short stature as well as the typical features of PHARC. Sequence analysis of ABHD12 revealed a novel heterozygous c.1129A>T (p.Lys377*) mutation. Targeted comparative genomic hybridization detected a 59-kb deletion that encompasses exon 1 of ABHD12 and exons 1-4 of an adjacent gene, GINS1, and includes the promoters of both genes. The heterozygous deletion was also carried by the patient's asymptomatic mother. Quantitative reverse transcription-PCR demonstrated ∼50% decreased expression of ABHD12 RNA in lymphoblastoid cell lines from both individuals. Activity-based protein profiling of serine hydrolases revealed absence of ABHD12 hydrolase activity in the patient and 50% reduction in her mother. This is the first report of compound heterozygosity in PHARC and the first study to describe how a mutation might affect ABHD12 expression and function. The possible involvement of haploinsufficiency for GINS1, a DNA replication complex protein, in the short stature of the patient and her mother requires further studies.

Evaluation of Chlamydia trachomatis and Neisseria gonorrhoeae detection in urine, endocervical, and vaginal specimens by a multiplexed isothermal thermophilic helicase-dependent amplification (tHDA) assay.

We have developed a new research assay that combines sequence-specific sample preparation and isothermal amplification for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae infections. The assay targets both the omp gene and the cryptic plasmid of C. trachomatis and the multicopy opa gene of N. gonorrhoeae, which are amplified and detected in a single reaction. We evaluated the ability of the assay to detect C. trachomatis and N. gonorrhoeae infections in first-catch urine, swab, and liquid-based cytology samples. Total agreement between the new assay and APTIMA Combo 2 varied between 95.3% and 100%, depending on the sample type and target detected. Total agreement between the new assay and BD ProbeTec varied between 96.7% and 100%, depending on the sample type and target detected. The assay has a simple work flow, and endpoint results can be achieved in 3 h, including sample preparation. The assay described here was evaluated for research use and was compared to commercially available assays.

Reproduction of melting behavior for vitrified hillforts based on amphibolite, granite, and basalt lithologies.

European Bronze and Iron Age vitrified hillforts have been known since the 1700s, but archaeological interpretations regarding their function and use are still debated. We carried out a series of experiments to constrain conditions that led to the vitrification of the inner wall rocks in the hillfort at Broborg, Sweden. Potential source rocks were collected locally and heat treated in the laboratory, varying maximum temperature, cooling rate, and starting particle size. Crystalline and amorphous phases were quantified using X-ray diffraction both in situ, during heating and cooling, and ex situ, after heating and quenching. Textures, phases, and glass compositions obtained were compared with those for rock samples from the vitrified part of the wall, as well as with equilibrium crystallization calculations. 'Dark glass' and its associated minerals formed from amphibolite or dolerite rocks melted at 1000-1200 °C under reducing atmosphere then slow cooled. 'Clear glass' formed from non-equilibrium partial melting of feldspar in granitoid rocks. This study aids archaeological forensic investigation of vitrified hillforts and interpretation of source rock material by mapping mineralogical changes and glass production under various heating conditions.

A novel X-linked four-repeat tauopathy with Parkinsonism and spasticity.

The parkinsonian syndromes comprise a highly heterogeneous group of disorders. Although 15 loci are linked to predominantly familial Parkinson's disease (PD), additional PD loci are likely to exist. We recently identified a multigenerational family of Danish and German descent in which five males in three generations presented with a unique syndrome characterized by parkinsonian features and variably penetrant spasticity for which X-linked disease transmission was strongly suggested (XPDS). Autopsy in one individual failed to reveal synucleinopathy; however, there was a significant four-repeat tauopathy in the striatum. Our objective was to identify the locus responsible for this unique parkinsonian disorder. Members of the XPDS family were genotyped for markers spanning the X chromosome. Two-point and multipoint linkage analyses were performed and the candidate region refined by analyzing additional markers. A multipoint LOD(max) score of 2.068 was obtained between markers DXS991 and DXS993. Haplotype examination revealed an approximately 20 cM region bounded by markers DXS8042 and DXS1216 that segregated with disease in all affected males and obligate carrier females and was not carried by unaffected at-risk males. To reduce the possibility of a false-positive linkage result, multiple loci and genes associated with other parkinsonian or spasticity syndromes were excluded. In conclusion, we have identified a unique X-linked parkinsonian syndrome with variable spasticity and four-repeat tau pathology, and defined a novel candidate gene locus spanning approximately 28 Mb from Xp11.2-Xq13.3.

A Semi-Automated Tuberculosis Testing Workflow Reduces Manual Hazardous Sample Handling and Hands-On Time: A Proof-of-Concept Study.

A central tenet of good diagnostic laboratory practice is protecting laboratory staff from contact with sample-borne pathogens and dangerous chemicals. Automated sample-processing systems can reduce or eliminate the risk of exposure to infectious samples while providing results on par with, or better than, those from manually processed samples. In addition, hands-free automated processing may enable analysts to focus on higher order activities while eliminating the risk of repetitive strain injuries associated with manual pipetting. Here, we describe a semi-automated tuberculosis interferon-γ release assay (IGRA) workflow that includes an automated high-throughput sample-processing system. The system automates cap removal, automates sample mixing and aspiration of blood from lithium heparin collection tubes, and aliquots blood samples into multiple blood assay tubes for downstream testing without manual intervention. We show that automated results are comparable to manual methods without risk of analyst exposure or repetitive strain injury.

Familial dyskinesia and facial myokymia (FDFM): Follow-up of a large family and linkage to chromosome 3p21-3q21.

We previously reported a five-generation family manifesting an autosomal dominant disorder of facial myokymia and dystonic/choreic movements (FDFM). The dyskinetic episodes are initially paroxysmal but may become constant. With increasing age they may lessen or even disappear. The previous study excluded nine candidate genes chosen for their association with myokymia or chorea and two regions containing single or clustered ion channel genes. We now report identification by whole genome linkage analysis of a broad region on chromosome 3p21-3q21 that segregates with the disease in all 10 affected members in three generations who participated in the study. GENEHUNTER-MODSCORE Version 2.0.1 provided a maximum multipoint LOD score of 3.099. No other disorders primarily characterized by myokymia, dystonia, or chorea are known to map to this region. Identification of additional families with FDFM may narrow the critical region and facilitate the choice of candidate genes for further analysis.

Genetic Candidate Variants in Two Multigenerational Families with Childhood Apraxia of Speech.

Childhood apraxia of speech (CAS) is a severe and socially debilitating form of speech sound disorder with suspected genetic involvement, but the genetic etiology is not yet well understood. Very few known or putative causal genes have been identified to date, e.g., FOXP2 and BCL11A. Building a knowledge base of the genetic etiology of CAS will make it possible to identify infants at genetic risk and motivate the development of effective very early intervention programs. We investigated the genetic etiology of CAS in two large multigenerational families with familial CAS. Complementary genomic methods included Markov chain Monte Carlo linkage analysis, copy-number analysis, identity-by-descent sharing, and exome sequencing with variant filtering. No overlaps in regions with positive evidence of linkage between the two families were found. In one family, linkage analysis detected two chromosomal regions of interest, 5p15.1-p14.1, and 17p13.1-q11.1, inherited separately from the two founders. Single-point linkage analysis of selected variants identified CDH18 as a primary gene of interest and additionally, MYO10, NIPBL, GLP2R, NCOR1, FLCN, SMCR8, NEK8, and ANKRD12, possibly with additive effects. Linkage analysis in the second family detected five regions with LOD scores approaching the highest values possible in the family. A gene of interest was C4orf21 (ZGRF1) on 4q25-q28.2. Evidence for previously described causal copy-number variations and validated or suspected genes was not found. Results are consistent with a heterogeneous CAS etiology, as is expected in many neurogenic disorders. Future studies will investigate genome variants in these and other families with CAS.

Presence of alanine-to-valine substitutions in myofibrillogenesis regulator 1 in paroxysmal nonkinesigenic dyskinesia: confirmation in 2 kindreds.

BACKGROUND: Paroxysmal nonkinesigenic dyskinesia (PNKD) is a rare disorder characterized by attacks of involuntary movements brought on by stress, alcohol, or caffeine, but not by movement. An autosomal dominant form of this disorder was mapped to chromosome 2q33-36, and different missense mutations in exon 1 of the myofibrillogenesis regulator 1 (MR1) gene were identified recently in 2 kindreds. OBJECTIVES: To describe studies on a new pedigree with PNKD, to explore the possibility of locus heterogeneity, and to further delineate the spectrum of mutations in MR1 in 2 families with PNKD. DESIGN, SETTING, AND PATIENTS: All 10 exons of MR1 were sequenced in DNA from members of 2 pedigrees with autosomal dominant PNKD. RESULTS: Different missense mutations in exon 1 of MR1 that cosegregate with disease were identified in each multiplex family. These single-nucleotide mutations predicted substitution of valine for alanine in residue 7 in one family and residue 9 in the other. The same mutations were found in the only 2 families previously published. Family history and haplotype analysis make it unlikely that the families with the same mutations are related. CONCLUSIONS: The function of MR1 is unknown, but the 2 mutations identified in the 4 families with PNKD studied to date are predicted to disrupt the amino terminal alpha-helix suggesting that this region of the gene is critical for proper gene function under stressful conditions. Study of additional families will be important to determine whether analysis of a single exon (MR1 exon 1) is sufficient for genetic testing purposes.

A new dominant spinocerebellar ataxia linked to chromosome 19q13.4-qter.

BACKGROUND: The autosomal dominant spinocerebellar ataxias (SCAs) are a clinically and genetically heterogeneous group of neurodegenerative disorders. Although molecular genetic studies have so far implicated 16 loci in the etiology of these diseases, approximately 30% of families with SCAs remain unlinked. OBJECTIVES: To report the location of a gene causing a "pure" autosomal dominant cerebellar ataxia in one family and to describe the clinical phenotype. PATIENTS: We have identified a 4-generation American family of English and Dutch ethnicity with a pure cerebellar ataxia displaying an autosomal dominant pattern of inheritance. The disease typically has its onset in the third and fourth decades of life, shows no evidence of anticipation, progresses slowly, and does not appear to decrease life expectancy. Clinical DNA testing excluded SCA1, 2, 3, 6, 7, and 8. METHODS: A genome-wide linkage analysis at a 10 centimorgan (cM) level was performed with samples from 26 family members (11 affected, 10 clinically unaffected at risk, and 5 spouses). RESULTS: Assuming 90% penetrance, we found suggestive evidence of linkage to chromosome 19, with a lod score of 2.49 for D19S571. More detailed mapping in this region provided a maximum 2-point lod score of 2.57 at theta = 0 for D19S254 and a maximum multipoint lod score of 4.72 at D19S926. By haplotype construction a 22-cM critical region from D19S601 to the q telomere was defined. CONCLUSIONS: We have mapped a gene for an autosomal dominant SCA to chromosome 19q13.4-qter in one family. The critical region overlaps with the locus for SCA14, a disease described in a single Japanese family and characterized by axial myoclonus. Myoclonus was not seen in the family we studied, but it remains possible that the 2 disorders are allelic variants.

Autosomal dominant sensory/motor neuropathy with Ataxia (SMNA): Linkage to chromosome 7q22-q32.

The autosomal dominant (AD) spinocerebellar ataxias (SCAs) and hereditary sensory neuropathies (HSN) are heterogeneous disorders characterized by variable clinical, electrophysiological, and neuropathological profiles. The SCAs are clinically characterized by slowly progressive incoordination of gait often associated with poor coordination of hands, speech, and eyes. Peripheral neuropathy is not a frequent part of the SCA syndrome. In contrast, the HSNs are primarily characterized by progressive sensory loss. There is substantial clinical overlap between the various SCAs and the various HSNs, and they often cannot be differentiated on the basis of clinical or neuro-imaging studies. We have identified a five-generation American family of Irish ancestry with a unique neurological disorder displaying an AD pattern of inheritance. There was variable expressivity and severity of symptoms including sensory loss, ataxia, pyramidal tract signs, and muscle weakness. Nerve conduction studies were consistent with a sensory axonal neuropathy. Muscle biopsy revealed neurogenic atrophy and brain MRI showed mild cerebellar atrophy. To identify the responsible locus we pursued a whole genome linkage analysis. After analyzing 114 markers, linkage to D7S486 was detected with a two point LOD score of 4.79 at theta = 0.00. Evaluation of additional markers in the region provided a maximum LOD score of 6.36 at theta = 0.00 for marker D7S2554. Haplotype analysis delimited an approximately 14-cM region at 7q22-q32 between markers D7S2418 and D7S1804 cosegregating with the disease. Because this disorder does not easily fall into either the SCA or HSN categories, it is designated sensory/motor neuropathy with ataxia (SMNA).

Multiplex isothermal helicase-dependent amplification assay for detection of Chlamydia trachomatis and Neisseria gonorrhoeae.

Thermophilic helicase dependent amplification (tHDA), which employs helicase to unwind double-stranded DNA at constant temperature, is a relatively new isothermal nucleic acid amplification technology. In this study, the development and optimization of a 4-plex tHDA assay for detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are described. tHDA is combined with sequence-specific sample preparation on magnetic beads and homogeneous endpoint fluorescence detection using dual-labeled probes. This 4-plex tHDA assay was applied to the detection of 2 genes on CT and a multicopy gene on NG in the presence of an internal control. The assay showed high analytical sensitivity and specificity of simultaneous CT/NG detection and is compatible with a wide variety of sample types and media. The isothermal reaction conditions and homogeneous endpoint detection utilized in this assay are well suited for laboratory automation and high-throughput screening applications as well as for point-of-care testing.

A novel mutation in FHL1 in a family with X-linked scapuloperoneal myopathy: phenotypic spectrum and structural study of FHL1 mutations.

An X-linked myopathy was recently associated with mutations in the four-and-a-half-LIM domains 1 (FHL1) gene. We identified a family with late onset, slowly progressive weakness of scapuloperoneal muscles in three brothers and their mother. A novel missense mutation in the LIM2 domain of FHL1 (W122C) co-segregated with disease in the family. The phenotype was less severe than that in other reported families. Muscle biopsy revealed myopathic changes with FHL1 inclusions that were ubiquitin- and desmin-positive. This mutation provides additional evidence for X-linked myopathy caused by a narrow spectrum of mutations in FHL1, mostly in the LIM2 domain. Molecular dynamics (MD) simulations of the newly identified mutation and five previously published missense mutations in the LIM2 domain revealed no major distortions of the protein structure or disruption of zinc binding. There were, however, increases in the nonpolar, solvent-accessible surface area in one or both of two clusters of residues, suggesting that the mutant proteins have a variably increased propensity to aggregate. Review of the literature shows a wide range of phenotypes associated with mutations in FHL1. However, recognizing the typical scapuloperoneal phenotype and X-linked inheritance pattern will help clinicians arrive at the correct diagnosis.

Missense mutations in the regulatory domain of PKC gamma: a new mechanism for dominant nonepisodic cerebellar ataxia.

We report a nonepisodic autosomal dominant (AD) spinocerebellar ataxia (SCA) not caused by a nucleotide repeat expansion that is, to our knowledge, the first such SCA. The AD SCAs currently comprise a group of > or =16 genetically distinct neurodegenerative conditions, all characterized by progressive incoordination of gait and limbs and by speech and eye-movement disturbances. Six of the nine SCAs for which the genes are known result from CAG expansions that encode polyglutamine tracts. Noncoding CAG, CTG, and ATTCT expansions are responsible for three other SCAs. Approximately 30% of families with SCA do not have linkage to the known loci. We recently mapped the locus for an AD SCA in a family (AT08) to chromosome 19q13.4-qter. A particularly compelling candidate gene, PRKCG, encodes protein kinase C gamma (PKC gamma), a member of a family of serine/threonine kinases. The entire coding region of PRKCG was sequenced in an affected member of family AT08 and in a group of 39 unrelated patients with ataxia not attributable to trinucleotide expansions. Three different nonconservative missense mutations in highly conserved residues in C1, the cysteine-rich region of the protein, were found in family AT08, another familial case, and a sporadic case. The mutations cosegregated with disease in both families. Structural modeling predicts that two of these amino acid substitutions would severely abrogate the zinc-binding or phorbol ester-binding capabilities of the protein. Immunohistochemical studies on cerebellar tissue from an affected member of family AT08 demonstrated reduced staining for both PKC gamma and ataxin 1 in Purkinje cells, whereas staining for calbindin was preserved. These results strongly support a new mechanism for neuronal cell dysfunction and death in hereditary ataxias and suggest that there may be a common pathway for PKC gamma-related and polyglutamine-related neurodegeneration.