Biallelic Pathogenic Mutations Research Articles

Consensus guidelines for the monitoring and management of metachromatic leukodystrophy in the United States

Metachromatic leukodystrophy (MLD) is a fatal, progressive neurodegenerative disorder caused by biallelic pathogenic mutations in the ARSA (Arylsulfatase A) gene. With the advent of presymptomatic diagnosis and the availability of therapies with a narrow window for intervention, it is critical to define a standardized approach to diagnosis, presymptomatic monitoring, and clinical care. To meet the needs of the MLD community, a panel of MLD experts was established to develop disease-specific guidelines based on healthcare resources in the United States. This group developed a consensus opinion for best-practice recommendations, as follows: (i) Diagnosis should include both genetic and biochemical testing; (ii) Early diagnosis and treatment for MLD is associated with improved clinical outcomes; (iii) The panel supported the development of newborn screening to accelerate the time to diagnosis and treatment; (iv) Clinical management of MLD should include specialists familiar with the disease who are able to follow patients longitudinally; (v) In early onset MLD, including late infantile and early juvenile subtypes, ex vivo gene therapy should be considered for presymptomatic patients where available; (vi) In late-onset MLD, including late juvenile and adult subtypes, hematopoietic cell transplant (HCT) should be considered for patients with no or minimal disease involvement. This document summarizes current guidance on the presymptomatic monitoring of children affected by MLD as well as the clinical management of symptomatic patients. Future data-driven evidence and evolution of these recommendations will be important to stratify clinical treatment options and improve clinical care.

Lack of CCDC146, a ubiquitous centriole and microtubule-associated protein, leads to non-syndromic male infertility in human and mouse.

From a cohort of 167 infertile patients suffering from multiple morphological abnormalities of the flagellum (MMAF), pathogenic bi-allelic mutations were identified in the CCDC146 gene. In somatic cells, CCDC146 is located at the centrosome and at multiple microtubule-related organelles during mitotic division, suggesting that it is a microtubule-associated protein (MAP). To decipher the molecular pathogenesis of infertility associated with CCDC146 mutations, a Ccdc146 knock-out (KO) mouse line was created. KO male mice were infertile, and sperm exhibited a phenotype identical to CCDC146 mutated patients. CCDC146 expression starts during late spermiogenesis. In the spermatozoon, the protein is conserved but is not localized to centrioles, unlike in somatic cells, rather it is present in the axoneme at the level of microtubule doublets. Expansion microscopy associated with the use of the detergent sarkosyl to solubilize microtubule doublets suggests that the protein may be a microtubule inner protein (MIP). At the subcellular level, the absence of CCDC146 impacted all microtubule-based organelles such as the manchette, the head-tail coupling apparatus (HTCA), and the axoneme. Through this study, a new genetic cause of infertility and a new factor in the formation and/or structure of the sperm axoneme were characterized.

Lack of CCDC146, a ubiquitous centriole and microtubule-associated protein, leads to non-syndromic male infertility in human and mouse

From a cohort of 167 infertile patients suffering from multiple morphological abnormalities of the flagellum (MMAF), pathogenic bi-allelic mutations were identified in the CCDC146 gene. In somatic cells, CCDC146 is located at the centrosome and at multiple microtubule-related organelles during mitotic division, suggesting that it is a microtubule-associated protein (MAP). To decipher the molecular pathogenesis of infertility associated with CCDC146 mutations, a Ccdc146 knock-out (KO) mouse line was created. KO male mice were infertile, and sperm exhibited a phenotype identical to CCDC146 mutated patients. CCDC146 expression starts during late spermiogenesis. In the spermatozoon, the protein is conserved but is not localized to centrioles, unlike in somatic cells, rather it is present in the axoneme at the level of microtubule doublets. Expansion microscopy associated with the use of the detergent sarkosyl to solubilize microtubule doublets suggests that the protein may be a microtubule inner protein (MIP). At the subcellular level, the absence of CCDC146 impacted all microtubule-based organelles such as the manchette, the head–tail coupling apparatus (HTCA), and the axoneme. Through this study, a new genetic cause of infertility and a new factor in the formation and/or structure of the sperm axoneme were characterized.

Apparition of germline mutation c.1395-1397del of MUTYH in Algerian consanguineous family with colorectal cancer

MUTYH is a glycosylase that removes adenine opposite 8-oxoguanine (OG) during base-excision repair of DNA. Variants of MUTYH defective in functional activity lead to MUTYH-associated polyposis (MAP), autosomal recessive predisposition to colorectal cancer (CRC). MAP combines clinical features with other hereditary CRC syndromes, and exhibits phenotypic overlap, particularly with Lynch syndrome (LS). To determine the impact of MUTYH mutations in colorectal adenomas and cancer susceptibility, this prospective objective screens the MUTYH gene in seventeen Eastern Algerian families with clinically suspected LS but without mismatch repair (MMR) mutations. Methods: We examined the presence of the mutations in the probands and their relatives using direct sequencing of the entire coding region of the MUTYH gene. Results: The biallelic and monoallelic pathogenic MUTYH mutations, c.1395_1397del, were discovered in a consanguineous family with CRC and gastric cancer as a novel finding in our Eastern Algerian population. Conclusion: High rates of consanguinity in Algerian population increase the risk of CRC caused by biallelic mutations in the MUTYH gene. In our families, the LS and MAP phenotypes might coexist.

The emergence of Fanconi anaemia type S: a phenotypic spectrum of biallelic BRCA1 mutations.

BRCA1 is involved in the Fanconi anaemia (FA) pathway, which coordinates repair of DNA interstrand cross-links. FA is a rare genetic disorder characterised by bone marrow failure, cancer predisposition and congenital abnormalities, caused by biallelic mutations affecting proteins in the FA pathway. Germline monoallelic pathogenic BRCA1 mutations are known to be associated with hereditary breast/ovarian cancer, however biallelic mutations of BRCA1 were long predicted to be incompatible with embryonic viability, hence BRCA1 was not considered to be a canonical FA gene. Despite this, several patients with biallelic pathogenic BRCA1 mutations and FA-like phenotypes have been identified - defining a new FA type (FA-S) and designating BRCA1 as an FA gene. This report presents a scoping review of the cases of biallelic BRCA1 mutations identified to date, discusses the functional effects of the mutations identified, and proposes a phenotypic spectrum of BRCA1 mutations based upon available clinical and genetic data. We report that this FA-S cohort phenotype includes short stature, microcephaly, facial dysmorphisms, hypo/hyperpigmented lesions, intellectual disability, chromosomal sensitivity to crosslinking agents and predisposition to breast/ovarian cancer and/or childhood cancers, with some patients exhibiting sensitivity to chemotherapy. Unlike most other types of FA, FA-S patients lack bone marrow failure.

Atypical hemolytic uremic syndrome in the era of terminal complement inhibition: an observational cohort study

AbstractHistorically, the majority of patients with complement-mediated atypical hemolytic uremic syndrome (CaHUS) progress to end-stage kidney disease (ESKD). Single-arm trials of eculizumab with a short follow-up suggested efficacy. We prove, for the first time to our knowledge, in a genotype matched CaHUS cohort that the 5-year cumulative estimate of ESKD-free survival improved from 39.5% in a control cohort to 85.5% in the eculizumab-treated cohort (hazard ratio, 4.95; 95% confidence interval [CI], 2.75-8.90; P = .000; number needed to treat, 2.17 [95% CI, 1.81-2.73]). The outcome of eculizumab treatment is associated with the underlying genotype. Lower serum creatinine, lower platelet count, lower blood pressure, and younger age at presentation as well as shorter time between presentation and the first dose of eculizumab were associated with estimated glomerular filtration rate >60 ml/min at 6 months in multivariate analysis. The rate of meningococcal infection in the treated cohort was 550 times greater than the background rate in the general population. The relapse rate upon eculizumab withdrawal was 1 per 9.5 person years for patients with a pathogenic mutation and 1 per 10.8 person years for those with a variant of uncertain significance. No relapses were recorded in 67.3 person years off eculizumab in those with no rare genetic variants. Eculizumab was restarted in 6 individuals with functioning kidneys in whom it had been stopped, with no individual progressing to ESKD. We demonstrated that biallelic pathogenic mutations in RNA-processing genes, including EXOSC3, encoding an essential part of the RNA exosome, cause eculizumab nonresponsive aHUS. Recessive HSD11B2 mutations causing apparent mineralocorticoid excess may also present with thrombotic microangiopathy.

Contribution of heterozygous PCSK1 variants to obesity and implications for precision medicine: a case-control study.

Rare biallelic pathogenic mutations in PCSK1 (encoding proprotein convertase subtilisin/kexin type 1 [PC1/3]) cause early-onset obesity associated with various endocrinopathies. Setmelanotide has been approved for carriers of these biallelic mutations in the past 3 years. We aimed to perform a large-scale functional genomic study focusing on rare heterozygous variants of PCSK1 to decipher their putative impact on obesity risk. This case-control study included all participants with overweight and obesity (ie, cases) or healthy weight (ie, controls) from the RaDiO study of three community-based and one hospital-based cohort in France recruited between Jan 1, 1995, and Dec 31, 2000. In adults older than 18 years, healthy weight was defined as BMI of less than 25·0 kg/m2, overweight as 25·0-29·9 kg/m2, and obesity as 30·0 kg/m2 or higher. Participants with type 2 diabetes had fasting glucose of 7·0 mmol/L or higher or used treatment for hyperglycaemia (or both) and were negative for islet or insulin autoantibodies. Functional assessment of rare missense variants of PCSK1 was performed. Pathogenicity clusters of variants were determined with machine learning. The effect of each cluster of PCSK1 variants on obesity was assessed using the adjusted mixed-effects score test. All 13 coding exons of PCSK1 were sequenced in 9320 participants (including 7260 adults and 2060 children and adolescents) recruited from the RaDiO study. We detected 65 rare heterozygous PCSK1 variants, including four null variants and 61 missense variants that were analysed in vitro and clustered into five groups (A-E), according to enzymatic activity. Compared with the wild-type, 15 missense variants led to complete PC1/3 loss of function (group A; reference) and rare exome variant ensemble learner (REVEL) led to 15 (25%) false positives and four (7%) false negatives. Carrying complete loss-of-function or null PCSK1 variants was significantly associated with obesity (six [86%] of seven carriers vs 1518 [35%] of 4395 non-carriers; OR 9·3 [95% CI 1·5-177·4]; p=0·014) and higher BMI (32·0 kg/m2 [SD 9·3] in carriers vs 27·3 kg/m2 [6·5] in non-carriers; mean effect π 6·94 [SE 1·95]; p=0·00029). Clusters of PCSK1 variants with partial or neutral effect on PC1/3 activity did not have an effect on obesity or overweight and on BMI. Only carriers of heterozygous, null, or complete loss-of-function PCSK1 variants cause monogenic obesity and, therefore, might be eligible for setmelanotide. In silico tests were unable to accurately detect these variants, which suggests that in vitro assays are necessary to determine the variant pathogenicity for genetic diagnosis and precision medicine purposes. Agence Nationale de la Recherche, European Research Council, National Center for Precision Diabetic Medicine, European Regional Development Fund, Hauts-de-France Regional Council, and the European Metropolis of Lille.

Plasma Level of Pyrophosphate Is Low in Pseudoxanthoma Elasticum Owing to Mutations in the ABCC6 Gene, but It Does Not Correlate with ABCC6 Genotype.

Pseudoxanthoma elasticum (PXE), a monogenic disorder resulting in calcification affecting the skin, eyes and peripheral arteries, is caused by mutations in the ABCC6 gene, and is associated with low plasma inorganic pyrophosphate (PPi). It is unknown how ABCC6 genotype affects plasma PPi. We studied the association of ABCC6 genotype (192 patients with biallelic pathogenic ABCC6 mutations) and PPi levels, and its association with the severity of arterial and ophthalmological phenotypes. ABCC6 variants were classified as truncating or non-truncating, and three groups of the 192 patients were formed: those with truncating mutations on both chromosomes (n = 121), those with two non-truncating mutations (n = 10), and a group who had one truncating and one non-truncating ABCC6 mutation (n = 61). The hypothesis formulated before this study was that there was a negative association between PPi level and disease severity. Our findings confirm low PPi in PXE compared with healthy controls (0.53 ± 0.15 vs. 1.13 ± 0.29 µM, p < 0.01). The PPi of patients correlated with increasing age (β: 0.05 µM, 95% CI: 0.03-0.06 per 10 years) and was higher in females (0.55 ± 0.17 vs. 0.51 ± 0.13 µM in males, p = 0.03). However, no association between PPi and PXE phenotypes was found. When adjusted for age and sex, no association between PPi and ABCC6 genotype was found. Our data suggest that the relationship between ABCC6 mutations and reduced plasma PPi may not be as direct as previously thought. PPi levels varied widely, even in patients with the same ABCC6 mutations, further suggesting a lack of direct correlation between them, even though the ABCC6 protein-mediated pathway is responsible for ~60% of this metabolite in the circulation. We discuss potential factors that may perturb the expected associations between ABCC6 genotype and PPi and between PPi and disease severity. Our findings support the argument that predictions of pathogenicity made on the basis of mutations (or on the structure of the mutated protein) could be misleading.

A novel mutation in the proteoglycan 4 gene causing CACP syndrome: two sisters report

BackgroundCamptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome, caused by biallelic pathogenic mutations in the proteoglycan 4 (PRG4) gene, is characterized by early-onset camptodactyly, noninflammatory arthropathy, coxa vara deformity, and rarely, pericardial effusion. This syndrome can mimic juvenile idiopathic arthritis. CACP syndrome is caused by mutations in the proteoglycan 4 (PRG4) gene. To date, only 36 pathogenic mutations have been reported in this gene, but none have been reported from Azerbaijan.Case presentationHerein, we report two siblings presented with chronic polyarthritis, had a prior diagnosis of juvenile idiopathic arthritis, but was subsequently diagnosed as CACP syndrome with novel mutation in the PRG4 gene.ConclusionOur report expands the knowledge of PRG4 mutations, which will aid in CACP patient counseling.

Colchicine treatment can be discontinued in a selected group of pediatric FMF patients

ObjectivesFamilial Mediterranean Fever (FMF) patients are required to adhere to a life-long treatment with colchicine, primarily for preventing amyloidosis. As some patients may be asymptomatic for long periods of time, it remains unclear whether it is possible to discontinue colchicine treatment in a selective group of patients. We aimed to identify predictive characteristics for a successful cessation of colchicine therapy.MethodsOut of 646 FMF pediatric patients followed in our referral FMF clinic, colchicine treatment was discontinued in 51 patients. In this study we compared the genetic, demographic, and clinical characteristics between patients for whom a successful cessation of therapy was made (Group 1; n = 21) and patients for whom cessation of therapy was deemed a failure (Group 2; n = 30) and consequently had to resume colchicine therapy.ResultsPatients for whom a successful cessation of therapy was achieved had no biallelic pathogenic MEFV mutations, were less likely to have “severe attacks” (two or more FMF characteristic symptoms) (24% vs 80%; P = 0.000067) and did not require higher than 1 mg/day of colchicine, prior to the drug cessation. Remission duration under colchicine treatment was significantly higher in group 1 compared with group 2 (4.36 years ±2.12 vs 2.53 years ±2; P = 0.0036).ConclusionThis study supports the concept of colchicine free remission in a minority of FMF patients (3%). Holding treatment, under close monitoring, may be reasonable when selecting the appropriate patients.

ODP149 Hypertriglyceridemia-Induced Acute Pancreatitis in Second Trimester of Pregnancy

Abstract Background Acute pancreatitis (AP) during pregnancy is a rare, potentially life-threatening disease, with an incidence of 1 case per 1,000-10,000. Hypertriglyceridemia (HTG)-induced pancreatitis accounts for only 5% of cases. Here we describe a rare case of HTG-induced AP during the second trimester of pregnancy, which was treated with concurrent insulin and plasmapheresis. Clinical Case A 35-year-old multigravida female was admitted for preterm premature rupture of membranes at 26 weeks gestation. Symptoms began on day 8 of admission and included severe epigastric pain radiating to the back. On exam, there was significant epigastric tenderness on palpation. There were no xanthelasmas or tendon xanthomas seen. She was afebrile but tachycardic. Laboratory evaluation noted a triglyceride (TG) level of &amp;gt;5,680 mg/dL (n&amp;lt;150), amylase 201 U/L (n&amp;lt;100) and lipase 277 U/L (n&amp;lt;60), consistent with AP. She was euglycemic. CT of the abdomen showed interstitial edematous pancreatitis with a peripancreatic collection. She was placed on NPO and started on intravenous (IV) fluid therapy, in combination with IV insulin and 10% dextrose. The patient also underwent one session of plasmapheresis. TG levels downtrended rapidly to 3,585 mg/dL within 24 hours. Once TG levels decreased below 1,000 mg/dL, insulin and dextrose infusions were stopped, and combination therapy of fenofibrate, omega-3 fatty acids, and low-fat low-carbohydrate diet was started. At 28 weeks and 5 days gestation, a cesarean section was performed due to suspected fetal distress. The patient was discharged on fenofibrate and Omega-3 fatty acids with a TG level of 456 mg/dL. Genetic testing revealed a heterozygous variant in the LPL gene mutation (c.644G&amp;gt;A; p. Gly215Glu) and a heterozygous variant of uncertain significance (VUS) in the ABCA1 gene (c.1765G&amp;gt;A; p. Val589Ile). She had no known family history of hyperlipidemia or cardiovascular disease. Conclusion Lipoprotein lipase (LPL) deficiency is an autosomal recessive disorder caused by biallelic pathogenic mutations in the LPL gene. The heterozygous c.644G&amp;gt;A variant has been previously described in several patients with LPL deficiency, however its impact on the function of the LPL protein has not yet been clearly defined. The ABCA1 gene is associated with Tangier disease, characterized by very low HDL levels and HTG. The ABCA1 gene variant detected in this case is classified as VUS as its effect on the gene function is not yet known. Further investigation is warranted to understand the role of these variants in familial dyslipidemia. Aside from the described patient, only one other case report of HCT-induced AP treated with concomitant plasmapheresis and IV insulin therapy has been reported in the literature. There are no published guidelines regarding the optimal treatment for HTG-induced AP in pregnancy. Combined treatment modality with plasmapheresis and IV insulin seems to be effective, however, its risks and benefits should be carefully assessed. Presentation: No date and time listed

A new rare homozygous mutation in the POLR3A gene causes ataxo-spasmodic leukodystrophy

Polymerase III (Pol III) related leukodystrophy is a rare class of leukodystrophy, recently recognized affecting the nervous system and other body systems with typical clinical presentation and imaging results. The diagnosis is made by characteristic combination of clinical signs, brain magnetic resonance imaging results and the presence of pathogenic biallelic mutations in specific genes: POLR3A, POLR3B, POLR3C which encode the RNA polymerase III enzyme subunits. We present the case of a 32-year-old young man who presented with spastic ataxia due to a new rare mutation in the POLR3A gene, splicing variant c.3892-5C &gt; T.

Templated Insertions Are Associated Specifically with BRCA2 Deficiency and Overall Survival in Advanced Ovarian Cancer.

Small, templated insertions indicative of theta-mediated end-joining likely can be used in conjunction with other HRD mutational signatures as a prognostic tool for patient response to therapies targeting HR deficiency.

Clinical and genetic features of sitosterolemia in Japan

Background and aimClinical manifestations and genetic backgrounds of Japanese patients with sitosterolemia have been unclear. Materials and methodsWe searched PubMed for studies using the keywords “sitosterolemia” or “phytosterolemia” and “Japan”. Moreover, we added information from the members of the Committee on Primary Dyslipidemia under the Research Program on Rare and Intractable Disease of the Ministry of Health, Labour and Welfare (MHLW) of Japan. ResultsWe identified 36 patients with sitosterolemia caused by biallelic pathogenic mutations in the ATP-binding cassette subfamily G member 5 (ABCG5) or ATP-binding cassette subfamily G member 8 (ABCG8) from 31 families in Japan. The diagnosed age ranged from 0 to 64 years (median 13 years). The median sitosterol and LDL cholesterol levels were 100 μg/ml (IQR: 50–183), and 193 mg/dl (IQR: 108–295), respectively. All the patients exhibited cutaneous and/or tendon xanthomas, up to 9 (25%) patients exhibited premature coronary artery disease, 5 (16%) patients exhibited arthritis, and 8 (22%) patients exhibited blood abnormalities. Ezetimibe was administered to all the patients, including infantile cases, while statins, colestimide, evolocumab, probucol, and LDL apheresis were also used. ConclusionWe are providing a demographic overview of the clinical and genetic backgrounds of Japanese patients with sitosterolemia.

QR‐421a RNA therapy in retinitis pigmentosa due to mutations in USH2A: Stellar trial Phase[AP1] 1b/2 interim results

AbstractPurposeTo report Phase 1b/2 interim results of QR‐421a RNA therapy promoting USH2A exon 13 skipping. USH2A exon 13 mutations lead to non‐syndromic Retinitis Pigmentosa &amp; Usher syndrome type 2.MethodsStellar (NCT03780257) is a 24‐month, multicenter Phase 1b/2 single‐dose trial assessing 3 dose levels (50, 100, 200 μg) of QR‐421a in patients aged ≥18 years with biallelic USH2A pathogenic mutations with at least one in exon 13. Cohorts 1 &amp; 2 included subjects randomized to sham‐procedure or QR‐421a. Primary endpoints: frequency &amp; severity of adverse events (AEs). Secondary endpoints: change in best‐corrected visual acuity (BCVA), static perimetry &amp; ellipsoid zone [EZ] area.Results20 subjects were enrolled, 14 received QR‐421a &amp; 6 received sham. Response to QR‐421a was similar for all doses. No serious AE or inflammation was observed. Two subjects had worsening of pre‐existing conditions: one with cataracts (not treatment‐related) &amp; one with cystoid macular edema (being managed with standard care). BCVA stabilization was observed in QR‐421a‐treated eyes (TE), versus a decline in untreated eyes (UE). At week 48, mean BCVA benefit was 6.0 &amp; 9.3 letters in all QR‐421a‐treated &amp; advanced subjects (n = 6; baseline BCVA of &lt;70 letters) respectively. No BCVA benefit was observed in sham‐treated eyes (SE). Mean change from baseline of the EZ‐area was +15.0% in TE, –26.4% in UE, &amp; –12.5% in SE at week 24. For static perimetry at week 12, the mean number of locations (loci) that improved by ≥7 dB compared to baseline was 9.2 loci versus 6.1 loci in TE versus UE in all QR‐421a‐treated subjects &amp; 12.9 loci versus 6.9 loci in early moderate‐stage subjects (n = 8; baseline BCVA of ≥70 letters). SE responded similarly to UE.ConclusionsQR‐421a was well tolerated &amp; demonstrated evidence of disease stabilization in visual acuity, &amp; improvements in retinal sensitivity &amp; retinal structural imaging data. An open‐label extension trial &amp; 2 Phase 2/3 trials are planned.

Lomitapide Reduces LDL-C and Favourably Affects Carotid Intima Media Thickness in Adult Patients with Homozygous Familial Hypercholesterolaemia in a Real-World Setting

<h3>Lead Author's Financial Disclosures</h3> D.B. has received consulting fees from Amryt. <h3>Study Funding</h3> Amryt Pharma. <h3>Background/Synopsis</h3> Homozygous familial hypercholesterolaemia (HoFH) is a rare genetic condition characterized by markedly elevated levels of low-density lipoprotein cholesterol (LDL-C) secondary to bi-allelic pathogenic mutations affecting key proteins in the LDL receptor pathway. Lomitapide is a microsomal triglyceride transfer protein (MTP) inhibitor that acts independently of the LDL receptor and is licenced for the treatment of adult patients with HoFH. To date, there are few prospective cardiovascular outcomes data for HoFH patients receiving lomitapide. <h3>Objective/Purpose</h3> To evaluate the effect of lomitapide use on carotid intima-media thickness (CIMT) in patients with HoFH. <h3>Methods</h3> Thirteen HoFH patients (mean+/-SD age 29.3+/-12.5 years) in seven global centers were treated in accordance with the lomitapide product label and local clinical practice. Patients underwent routine laboratory testing, including lipid and liver panels. CIMT imaging was recorded to monitor atherosclerotic cardiovascular disease (ASCVD) according to local protocols. <h3>Results</h3> Lomitapide resulted in marked decreases in LDL-C (mean+/-SD: 76.5+/-11.7%; range 56.8-93.9% at the lowest point). Notably, eight patients achieved LDL-C levels below the European Atherosclerosis Society target of <100mg/dL, and three patients achieved LDL-C <70mg/dL at least once. Over a mean follow-up of 3.9+/-2.3 years between measurements, CIMT regressed in 7 cases. The remaining patients demonstrated no progression (Supplementary Table). In two patients where assessments of plaque area were available, modest regression or stabilisation in CIMT (0.82mm to 0.65mm over 24 months [20.7% reduction]; 0.56mm to 0.57mm over 26 months [1.8% increase]) was accompanied by clinically significant regression of plaque area (147.1mm2 to 120.5mm2 [18.1% reduction]; 64.0 mm2to 42.1 mm2 [34.7% reduction]. Calculation of vascular age in n=9 patients indicated mean improvement of -18.8+/-32.6 years (range -60 to +30 years). Elevations in ALT/AST enzyme levels >3x upper limit of normal were evident in 6/13 patients. In all cases, these elevations either resolved without intervention or were managed with brief, transient reductions in lomitapide dose. <h3>Conclusions</h3> Lomitapide dramatically reduces LDL-C levels in patients with HoFH, and results in stabilisation and/or regression of CIMT, which is an established marker of ASCVD risk.

RNA-seq of peripheral blood mononuclear cells of congenital generalized lipodystrophy type 2 patients

Illumina RNA-seq analysis was used to characterize the whole transcriptomes of peripheral blood mononuclear cells (PBMCs) from patients with congenital generalized lipodystrophy. RNA-seq information for seven patients with type 2 congenital generalized lipodystrophy (CGL2; Berardinelli-Seip congenital lipodystrophy, BSCL2) was obtained and compared with similar information for seven age- and sex-matched healthy control subjects. All seven CGL2 patients carried biallelic pathogenic mutations affecting the BSCL2 gene and had clinical symptoms of varying severity. The findings provide the whole-transcriptome signatures of PBMCs of CGL2 patients, allowing further exploration of gene expression patterns/signatures associated with the various clinical symptoms of patients with this disease.

A Human Pleiotropic Multiorgan Condition Caused by Deficient Wnt Secretion

BackgroundStructural birth defects occur in approximately 3% of live births; most such defects lack defined genetic or environmental causes. Despite advances in surgical approaches, pharmacologic prevention remains largely out of reach.MethodsWe queried worldwide databases of 20,248 families that included children with neurodevelopmental disorders and that were enriched for parental consanguinity. Approximately one third of affected children in these families presented with structural birth defects or microcephaly. We performed exome or genome sequencing of samples obtained from the children, their parents, or both to identify genes with biallelic pathogenic or likely pathogenic mutations present in more than one family. After identifying disease-causing variants, we generated two mouse models, each with a pathogenic variant “knocked in,” to study mechanisms and test candidate treatments. We administered a small-molecule Wnt agonist to pregnant animals and assessed their offspring.ResultsWe identified homozygous mutations in WLS, which encodes the Wnt ligand secretion mediator (also known as Wntless or WLS) in 10 affected persons from 5 unrelated families. (The Wnt ligand secretion mediator is essential for the secretion of all Wnt proteins.) Patients had multiorgan defects, including microcephaly and facial dysmorphism as well as foot syndactyly, renal agenesis, alopecia, iris coloboma, and heart defects. The mutations affected WLS protein stability and Wnt signaling. Knock-in mice showed tissue and cell vulnerability consistent with Wnt-signaling intensity and individual and collective functions of Wnts in embryogenesis. Administration of a pharmacologic Wnt agonist partially restored embryonic development.ConclusionsGenetic variations affecting a central Wnt regulator caused syndromic structural birth defects. Results from mouse models suggest that what we have named Zaki syndrome is a potentially preventable disorder. (Funded by the National Institutes of Health and others.)

Clinical and genetic characteristics of 21 Spanish patients with biallelic pathogenic SPG7 mutations

Spastic paraplegia type 7 (SPG7) is one of the most common hereditary spastic paraplegias. SPG7 mutations most often lead to spastic paraparesis (HSP) and/or hereditary cerebellar ataxia (HCA), frequently with mixed phenotypes. We sought to clinically and genetically characterize a Spanish cohort of SPG7 patients. Patients were recruited from our HCA and HSP cohorts. We identified twenty-one patients with biallelic pathogenic SPG7 mutations. Mean age at onset was 37.4 years (SD ± 14.3). The most frequent phenotype was spastic ataxia (57%), followed by pure spastic paraplegia (19%) and complex phenotypes (19%). Isolated patients presented with focal or multifocal dystonia, subclinical myopathy or ophthalmoplegia. p.Ala510Val was the most frequent pathogenic variant encountered. Compound heterozygous for p.Ala510Val displayed younger onset (p < 0.05) and more complex phenotypes (p < 0.05) than p.Ala510Val homozygotes. Two novel variants were found: p.Lys559Argfs*33 and p.Ala312Glu. In conclusion, spastic ataxia is the most common phenotype found in Spanish patients. Nonetheless, SPG7 analysis should also be considered in patients with less frequent clinical findings such as dystonia or ophthalmoplegia especially when these symptoms are associated with mild spastic ataxia.

M680I/M694V Heterozygous Mutation in Early Onset Familial Mediterranean Fever

Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disorder affecting individuals with biallelic pathogenic mutations in the MEFV gene. The disease is characterized by recurrent attacks of fever and serosal inflammation as manifested by abdominal and chest pain. This case report presents an FMF case with a 3-year history of pain crises consisting of severe abdominal pain and fever, lasting up to 72 h. Genetic investigation identified an uncommon heterozygous mutation in the MEFV gene. This mutation is associated with a more severe phenotype of FMF and may lead to an early onset of the disease.