Features of multiple self-healing squamous epithelioma and Loeys-Dietz syndrome in a patient with a novel TGFBR1 variant.

Multiple self-healing squamous epithelioma (MSSE, Ferguson-Smith disease) and Loeys-Dietz syndrome (LDS) are allelic conditions associated with pathogenic variants in the transforming growth factor beta receptor 1 gene (TGFBR1). We describe a patient with a novel missense variant in this gene: c.664G > A, p.[Gly222Arg], who clinically presents with both syndromes. The patient also has a history of gastric antral vascular ectasia, which has not been reported previously in LDS.

Diagnosis of spinal xanthomatosis by next-generation sequencing: identifying a rare, treatable mimic of hereditary spastic paraparesis.

Cerebrotendinous xanthomatosis is an autosomal recessive disorder of bile acid metabolism causing a range of progressive neurological symptoms. Even in the presence of the classical triad of neurological dysfunction, tendon xanthoma and early onset cataracts, the diagnosis is often missed. It can mimic more common conditions such as hereditary spastic paraparesis or multiple sclerosis, particularly if the phenotype is spinal xanthomatosis where the disease causes a spastic paraplegia. Early recognition and treatment with chenodeoxycholic acid may prevent irreversible neurological damage. The introduction of next-generation sequencing to screen for a large number of genetic disorders associated with progressive spastic paraparesis will allow earlier identification and treatment of these patients and their families, and will particularly help in atypical cases such as the patient described here.

Clinico-pathological features in amyotrophic lateral sclerosis with expansions in C9ORF72.

Intronic expansion of the GGGGCC hexanucleotide repeat within the C9ORF72 gene causes frontotemporal dementia and amyotrophic lateral sclerosis/motor neuron disease in both familial and sporadic cases. Initial reports indicate that this variant within the frontotemporal dementia/amyotrophic lateral sclerosis spectrum is associated with transactive response DNA binding protein (TDP-43) proteinopathy. The amyotrophic lateral sclerosis/motor neuron disease phenotype is not yet well characterized. We report the clinical and pathological phenotypes associated with pathogenic C9ORF72 mutations in a cohort of 563 cases from Northern England, including 63 with a family history of amyotrophic lateral sclerosis. One hundred and fifty-eight cases from the cohort (21 familial, 137 sporadic) were post-mortem brain and spinal cord donors. We screened DNA for the C9ORF72 mutation, reviewed clinical case histories and undertook pathological evaluation of brain and spinal cord. Control DNA samples (n = 361) from the same population were also screened. The C9ORF72 intronic expansion was present in 62 cases [11% of the cohort; 27/63 (43%) familial, 35/500 (7%) cases with sporadic amyotrophic lateral sclerosis/motor neuron disease]. Disease duration was significantly shorter in cases with C9ORF72-related amyotrophic lateral sclerosis (30.5 months) compared with non-C9ORF72 amyotrophic lateral sclerosis/motor neuron disease (36.3 months, P < 0.05). C9ORF72 cases included both limb and bulbar onset disease and all cases showed combined upper and lower motor neuron degeneration (amyotrophic lateral sclerosis). Thus, clinically, C9ORF72 cases show the features of a relatively rapidly progressive, but otherwise typical, variant of amyotrophic lateral sclerosis associated with both familial and sporadic presentations. Dementia was present in the patient or a close family member in 22/62 cases with C9ORF72 mutation (35%) based on diagnoses established from retrospective clinical case note review that may underestimate significant cognitive changes in late disease. All the C9ORF72 mutation cases showed classical amyotrophic lateral sclerosis pathology with TDP-43 inclusions in spinal motor neurons. Neuronal cytoplasmic inclusions and glial inclusions positive for p62 immunostaining in non-motor regions were strongly over-represented in the C9ORF72 cases. Extra-motor pathology in the frontal cortex (P < 0.0005) and the hippocampal CA4 subfield neurons (P < 0.0005) discriminated C9ORF72 cases strongly from the rest of the cohort. Inclusions in CA4 neurons were not present in non-C9ORF72 cases, indicating that this pathology predicts mutation status.

Spinocerebellar ataxias: an example of the challenges associated with genetic databases for dynamic mutations.

Locus-specific databases are an important source of information for diagnostic laboratories and a valued means of improving quality of genetic testing. Although increasingly frequent, databases for oligonucleotide repeat expansions are still scarce, due to factors that make them different and the building of databases much more difficult. Definition of what constitutes "the repeat" to measure is not a simple matter and correct sizing is not always straightforward. Reference ranges and penetrance classes are not easy to establish. Acceptable margins of error depend on the disease and allele-size distribution, and vary according to size range and pathogenic significance. Inter- and intralaboratorial variance is well documented and allele distribution may vary among populations. The spinocerebellar ataxias, used only as an example of those difficulties, are also a highly heterogeneous group, which includes loci with both pathogenic repeat expansions and point mutations or insertions/deletions. They display a variable, but often overlapping phenotype, where genotype-phenotype correlation is difficult or nonexistent. Standard (Human Genome Variation Society) nomenclature is not appropriate for oligonucleotide repeats, as established at harmonization among all EMQN (European Molecular Genetics Network) external quality assessment (EQA) schemes for "repeat disorders." Curation of such databases is a difficult task, but one that needs to be addressed adequately and without much delay.

Diagnosis of Spinocerebellar Ataxias Caused by Trinucleotide Repeat Expansions.

Spinocerebellar ataxias (SCAs) are a group of disorders that are both clinically and genetically heterogeneous. They usually demonstrate onset in adulthood, but some forms may have juvenile or infantile onset. There are many different types of SCA, demonstrating different modes of inheritance and types of mutation. The most common forms are due to dominantly inherited expansions in trinucleotide repeat sequences located within the coding region of the relevant genes, and these are readily identifiable by molecular genetic testing. In general, it is possible to test for these disorders using PCR-based assays, amplifying across the trinucleotide repeat regions and sizing the PCR products to determine the number of repeats. Larger expansions are generally associated with a more severe presentation of the disorder, and alternative methods may be necessary to detect these alleles. This protocol describes methods for detecting normal and expanded triplet repeat alleles in the most common SCA genes. © 2017 by John Wiley & Sons, Inc.

Concurrent amyotrophic lateral sclerosis and cystic fibrosis supports common pathways of pathogenesis.

Abstract We present a case of concurrent cystic fibrosis (CF) and amyotrophic lateral sclerosis (ALS). To our knowledge this is the first reported coincidence of these two diseases. Although TDP-43 dysfunction has been linked to both pathologies, it does not appear to be pivotal in this individual who does not display TDP-43 mediated aberrant splicing of the CFTR gene or carry a mutation in the TARDBP gene. Alternative reasons for the coincidence are discussed including medication, infection, hypoxia and loss of function of the CFTR channel. Our findings await validation by others, but as the prognosis of CF improves then clinicians in both fields should be aware of the possibilities highlighted by this case.

A novel MPZ gene mutation in exon 2 causing late-onset demyelinating Charcot-Marie-Tooth disease.

The myelin protein zero gene (MPZ) encodes the major structural protein component of myelin in the peripheral nervous system. More than 120 mutations in MPZ have been detected so far. Clinical phenotypes include CMT1B, CMT2, Dejerine-Sottas syndrome, and congenital hypomyelination neuropathy. We report a new previously unreported mutation in the MPZ gene causing a demyelinating peripheral neuropathy. The initial apparent absence of a family history resulted in the patient being treated for an inflammatory neuropathy with some subjective improvement. We subsequently identified another affected member of the same family with the same genotype leading to the correct diagnosis. Both the affected individuals had an 8-base pair deletion, c.160_167delTCCCGGGT in MPZ exon 2.

Consensus and controversies in best practices for molecular genetic testing of spinocerebellar ataxias.

Many laboratories worldwide are offering molecular genetic testing for spinocerebellar ataxias (SCAs). This is essential for differential diagnosis and adequate genetic counselling. The European Molecular Genetics Quality Network (EMQN) started an SCA external quality assessment scheme in 2004. There was a clear need for updated laboratory guidelines. EMQN and EuroGentest organized a Best Practice (BP) meeting to discuss current practices and achieve consensus. A pre-meeting survey showed that 36 laboratories (20 countries) conducted nearly 18 000 SCA tests the year before, and identified issues to discuss. Draft guidelines were produced immediately after the meeting and discussed online for several months. The final version was endorsed by EMQN, and harmonized with guidelines from other oligonucleotide repeat disorders. We present the procedures taken to organize the survey, BP meeting, as well as drafting and approval of BP guidelines. We emphasize the most important recommendations on (1) pre-test requirements, (2) appropriate methodologies and (3) interpretation and reporting, and focus on the discussion of controversial issues not included in the final document. In addition, after an extensive review of scientific literature, and responding to recommendations made, we now produce information that we hope will facilitate the activities of diagnostic laboratories and foster quality SCA testing. For the main loci, this includes (1) a list of repeat sequences, as originally published; (2) primers in use; and (3) an evidence-based description of the normal and pathogenic repeat-size ranges, including those of reduced penetrance and those in which there is still some uncertainty. This information will be maintained and updated in http://www.scabase.eu.