Clinical findings and structural analysis involving a patient with a novel KLHL15 variant

A de novo novel variant of uncertain significance p. (Arg532del) in the KLHL15 gene was identified by trio exome analysis in a child with global developmental delay, coarse facial features, repetitive behaviour, increased fatigability, poor feeding and gastro-oesophageal reflux. Comparative modelling and structural analysis were performed to gain insight into the effects of the variant on KLHL15 protein structure and function, with a view to aiding variant classification. The p. (Arg532del) variant affects a highly conserved residue within one of the Kelch repeats of the KLHL15 protein. This residue contributes to the stability of loop regions at the substrate binding surface of the protein; comparative modelling of the variant protein predicts altered topology at this surface, including at residue Tyr552, which is known to be important for substrate binding. We propose that it is highly probable that the p. (Arg532del) variant has a deleterious impact on KLHL15 structure, leading to a reduced level of protein function in vivo.

Genetic testing in motor neuron disease and frontotemporal dementia: a 5-year multicentre evaluation

INTRODUCTION

Motor neuron disease (MND) and frontotemporal dementia (FTD) comprise a neurodegenerative disease spectrum. Genetic testing and counselling is complex in MND/FTD owing to incomplete penetrance, variable phenotype and variants of uncertain significance. Affected patients and unaffected relatives are commonly referred to clinical genetics to consider genetic testing. However, no consensus exists regarding how such genetic testing should best be undertaken and on which patients.

OBJECTIVE

We sought to ascertain UK clinical genetics testing practice in MND/FTD referrals, with the aim of helping inform guideline development.

METHODS

MND/FTD clinical genetics referrals comprising both affected patients and unaffected relatives between 2012 and 2016 were identified and a standardised proforma used to collate data from clinical records.

RESULTS

301 referrals (70 affected, 231 unaffected) were reviewed across 10 genetics centres. Previously identified familial variants were known in 107 cases and 58% subsequently underwent testing (8 of 8 diagnostic and 54 of 99 predictive). The median number of genetic counselling appointments was 2 for diagnostic and 4 for predictive testing. Importantly, application of current UK Genomic Test Directory eligibility criteria would not have resulted in detection of all pathogenic variants observed in this cohort.

CONCLUSION

We propose pragmatic MND/FTD genetic testing guidelines based on appropriate genetic counselling.

T cell receptor α-chain polymorphic allele frequencies in Caucasians and Polynesians

Restriction length polymorphisms in the variable and constant regions of the T cell receptor alpha-chain were examined in 42 Caucasians, 29 Maoris and 27 Pacific Islanders. Southern blots of Taq I digested DNA were hybridized with the T cell receptor alpha-chain probe pY14. Our results confirm that a 1.4 kb T cell receptor alpha chain-Taq 1 band is allelic to a 0.5 kb band. A significant difference in the frequency of the 1.4 and 0.5 kb alleles of the variable region of the alpha-chain was detected in Caucasians when compared with Maoris or Pacific Islanders (P < 0.0001). No differences in the frequency of the 2.0 and 7.0 kb alleles of the constant region gene were detected between any of the racial groups. These data may be relevant to ethnic differences in susceptibility to immune disorders.

Intravenous immunoglobulin in acute rheumatic fever: a randomized controlled trial

BACKGROUND

Acute rheumatic fever (ARF) remains the leading cause of acquired heart disease in children worldwide. No therapeutic agent has been shown to alter the clinical outcome of the acute illness. Immunological mechanisms appear to be involved in the pathogenesis of ARF. Intravenous immunoglobulin (IVIG), a proven immunomodulator, may benefit cardiac conditions of an autoimmune nature. We investigated whether IVIG modified the natural history of ARF by reducing the extent and severity of carditis.

METHODS AND RESULTS

This prospective, double-blind, randomized, placebo-controlled trial evaluated IVIG in patients with a first episode of rheumatic fever, stratifying patients by the presence and severity of carditis before randomization. Patients were randomly allocated to receive 1 g/kg IVIG on days 1 and 2 and 0.4 g/kg on days 14 and 28, or they received a placebo infusion. Clinical, laboratory, and echocardiographic evaluation was performed at 0, 2, 4, 6, 26, and 52 weeks. Fifty-nine patients were treated, of whom 39 had carditis (including 4 subclinical) and/or migratory polyarthritis (n=39). There was no difference between groups in the rate of normalization of the erythrocyte sedimentation rate or acute-phase proteins at the 6-week follow-up. On echocardiography, 59% in the IVIG group and 69% in the placebo group had carditis at baseline. There was no significant difference in the cardiac outcome, including the proportion of valves involved, or in the severity of valvar regurgitation at 1 year. At 1 year, 41% of the IVIG and 50% of the placebo group had carditis.

CONCLUSIONS

IVIG did not alter the natural history of ARF, with no detectable difference in the clinical, laboratory, or echocardiographic parameters of the disease process during the subsequent 12 months.

Treatment of respiratory viral infection in an immunodeficient infant with ribavirin aerosol

An infant with severe combined immunodeficiency syndrome (SCIDS) secondary to adenosine deaminase deficiency had pneumonitis and combined infection with respiratory syncytial virus (RSV) and parainfluenza virus type 3 (PIV3). Four separate courses of ribavirin were delivered by small-particle aerosol. The PIV3 disappeared during the first course, and RSV disappeared after the fourth course on the 58th hospital day. Neither virus returned during profound immunosuppression for bone marrow transplantation. Secretory antibody to both viruses was found and may have assisted in recovery. Strains of RSV from the 9th, 15th, 29th, and 55th hospital days showed similar sensitivities to ribavirin in vitro. Ribavirin can be a useful drug in the treatment of respiratory viral infections in patients with SCIDS.