Musculoskeletal pain and muscular weakness as the main symptoms of adult hypophosphatasia in a Spanish cohort: clinical characterization and identification of a new ALPL gene variant.

INTRODUCTION: Hypophosphatasia (HPP) is a rare inherited disorder, caused by mutations in the alkaline phosphatase (ALPL) gene, which encodes for the tissue non-specific alkaline phosphatase (TNSALP) isoform of alkaline phosphatase (ALP). Adult HPP is one of the mild forms that presents with unspecific signs such as osteopenia, osteomalacia and muscle involvement. Our purpose was to identify and characterize possibly misdiagnosed adult HPP patients at a clinical and biochemical level. MATERIAL AND METHODS: At the laboratory of Miguel Servet University Hospital we retrospectively reviewed serum ALP levels in adults over a 48-month period. The clinical records of individuals with consistently low ALP levels were reviewed to exclude secondary causes. Those with persistent hypophosphatasemia were screened for symptoms of HPP. The study participants were evaluated at biochemical and genetic levels. RESULTS: We identified 705 ALP determinations (out of 384,000 processed) in 589 patients below the reference range (30 U/l). Only 21 patients with clinical signs and symptoms of HPP were selected for genetic testing. Finally, only 12 patients participated in the study, 83.3% of whom (10/12) harbored a pathogenic or likely pathogenic variant in a heterozygous state. The major symptoms of our cohort were the presence of musculoskeletal pain (100% of patients) and muscular weakness (83.3% patients). CONCLUSION: Mild HPP patients presenting with diffuse symptoms such as musculoskeletal pain may be undiagnosed or misdiagnosed as osteoporosis patients by routine diagnosis. It is important to identify these individuals, to avoid inappropriate treatment with antiresorptive drugs.

Incidence of Huntington disease in a northeastern Spanish region: a 13-year retrospective study at tertiary care centre.

BACKGROUND: Despite the progress in the knowledge of Huntington disease (HD) in recent years, the epidemiology continues uncertain, so the study of incidence becomes relevant. This is important since various factors (type of population, diagnostic criteria, disease-modifying factors, etc.) make these data highly variable. Therefore, the genetic diagnosis of these patients is important, since it unequivocally allows the detection of new cases. METHODS: Descriptive retrospective study with 179 individuals. Incidence of HD was calculated from the ratio of number of symptomatic cases newly diagnosed per 100,000 inhabitants per year during the period 2007-2019 in Aragon (Spain). RESULTS: 50 (27.9%) incident cases of HD (CAG repeat length ≥ 36) were identified from a total of 179 persons studied. The remaining 129/179 (72.1%) were HD negative (CAG repeat length < 36). 29 (58.0%) females and 21 (42.0%) males were confirmed as HD cases. The overall incidence was 0.648 per 100,000 patient-years. 11/50 positive HD cases (22.0%) were identified by performing a predictive test, without clinical symptoms. The minimum number of CAG repeats found was 9 and the most common CAG length among HD negative individuals was 16. CONCLUSIONS: Our incidence lied within the range reported for other Caucasian populations. Implementation of new techniques has allowed to determine the exact number of CAG repeats, which is especially important in patients with triplet expansions in an HD intermediate and/or incomplete penetrance allele, both in diagnostic, predictive and prenatal tests.

No increase in the CTG repeat size during transmission from parent with expanded allele: false suspicion of contraction phenomenon.

Objectives: Myotonic dystrophy type 1 (DM1), also known as Steinert's disease, is a chronic, progressive and disabling multisystemic disorder with a broad spectrum of severity that arises from an autosomal-dominant expansion of the Cytosine-Thymine-Guanine (CTG) triplet repeat in the 3' untranslated region of the DMPK gene (19q13.3). Case presentation: In this study, we report the case of a family with several intergenerational expansions of the CTG repeat, with an additional case of a false suspicion of contraction phenomenon due to TP-PCR limitations. Conclusions: The meiotic instability of the (CTG)n repeats leads to genetic anticipation where increased size of DM1 mutation and a more severe phenotype have been reported in affected individuals across generations. Even if extremely rare, a decrease in the CTG repeat size during transmission from parents to child can also occur, most frequently during paternal transmissions.

First case of very late-onset FHL2 in Spain with two variants in the PRF1 gene.

Hemophagocytic lymphohistiocytosis (HLH) is a rare but fatal disorder characterized by the proliferation and infiltration of macrophages and hyperactivated T lymphocytes that escape from the physiological control pathways and favour the existence of an environment of excessive inflammation and tissue destruction. HLH has been classified into two types: a primary or familial autosomal recessive form, caused by mutations in genes encoding proteins involved in the granule-dependent cytotoxic pathway (familial hemophagocytic lymphohistiocytosis [FHL] types 1-5); and other secondary or acquired form, generally associated with infections, malignancy, autoimmune diseases, metabolic disorders or primary immunodeficiencies. Since the first familial hemophagocytic lymphohistiocytosis-2 (FHL2) causative mutation in the PRF1 gene was described in 1999, more than 200 mutations have been identified to date. Here, we report the first case of very late-onset FHL2 in a Spanish 72-year-old female with splenomegaly, hypertriglyceridemia, hypofibrinogenemia, pancytopenia and marrow hemophagocytosis harbouring in heterozygosity two PRF1 variants proposed as causative in this study. The heterozygous mutation c.445G>A (p.Gly149Ser) identified in the exon 2 results in a missense mutation previously described as a probable pathogenic variant associated with the development of FHL2. Affecting the same exon, c.272C>T (p.Ala91Val) is the most prevalent variant of this gene. Although it was initially classified as benign, recent studies support its potential pathogenic role, considering it a variant of uncertain significance associated with a risk of developing FHL2. The genetic confirmation of FHL made possible an adequate counselling to the patient and direct relatives and provided important information for her control and follow-up.

[AZF gene microdeletions in azoospermic-oligozoospermic males]. / Microdeleciones del gen AZF en varones azoospérmicos-oligozoospérmicos.

BACKGROUND AND OBJECTIVE: The presence of microdeletions in the Y-chromosome azoospermia factor (AZF) region (YCMs) is considered the most frequent genetic cause of male infertility along with Klinefelter syndrome. The objective of this study was to investigate the frequencies and type of YCMs in infertile men in Aragon and to analyze the relationship between sex hormones, sperm count and microdeletions in them. PATIENTS AND METHODS: Retrospective descriptive study of 644 men who during 2006-2019 were screened for YCMs using YChromStrip (Operón, Spain) by PCR+reverse hybridization, spermiogram, karyotype and quantification of sex hormones. RESULTS: The frequency of YCMs was 3.88% (25/644), not being detected in any patient with mild or normospermic oligozoospermia, that is, in sperm counts higher than 5×106/mL. The group of azoospermic patients was the one that presented a higher frequency of YCMs (14.58%, 14/96). Deletions in the AZFc region were the most frequent (68%). 20% (5/25) of patients with YCMs also presented some type of karyotype abnormality that included aneuploidies, deletions, duplications and/or translocations. Sperm count was significantly lower and FSH and LH concentrations significantly higher in the group of patients with YCMs. CONCLUSIONS: YCMs screening is a key test in the diagnostic approach to male infertility. Obtaining an adequate result allows choosing suitable assisted reproduction techniques, preventing unnecessary treatments and the transmission of genetic defects to offspring.

Beyond the method change in clinical practice: evaluation of insulin-like growth factor I assay.

Objectives: Insulin-like growth factor I (IGF-I) is the preferred biomarker for diagnosing and monitoring growth-related disorders but its serum quantification presents several difficulties since different IGF-I assays still leads to different IGF-I concentrations, especially when results are either above or below the normal range. Methods: We conducted a prospective study between November and December 2020 at a tertiary University Hospital with 212 serum samples to determine the analytical performance of the IGF-I assay on the Cobas e411 (Roche Diagnostics) and compare it with that of the Immulite 2000XPi (Siemens). Results: In this work, we report for the first time the existence of discrepancies between IGF-I levels measured by Immulite 2000XPi and Cobas e411. Deming regression model provided a slope of 1.570 (95% CI: 1.395-1.745) and an intercept of -58.591 (95% CI: -89.151 to -28.030), with R2=0.967 and average bias of +53.061 with overestimation of IGF-I. It was found that Cobas e411 provides abnormally high IGF-I concentrations, but further studies are required to elucidate the cause of the discrepancies. Conclusions: Our data can alert clinicians and laboratory professionals of this situation and avoid misinterpretation of increased IGF-I levels as a therapeutic failure rather than as a problem associated with this method change.

A novel pathogenic variant in LCAT causing FLD. A case report.

BACKGROUND: Fish-eye disease (FED) is due to a partial deficiency in LCAT activity. Nevertheless, Familial lecithin-cholesterol acyltransferase deficiency (FLD), also called Norum disease, appears when the deficiency is complete. They are both rare genetic disorders inherited in an autosomal recessive manner. Clinical signs include decreased circulating HDL cholesterol and dense corneal opacity. Kidney injuries also affect patients suffering from FLD. The diagnosis of FLD is based on the presence of characteristic signs and symptoms and confirmed by genetic testing. CASE PRESENTATION: We present a case of a 63-year-old man showing an altered lipid profile with low HDL cholesterol, chronic kidney disease (CKD) and corneal disorders. He was referred to genetic counseling in order to discard genetic LCAT deficiency due to decreased visual acuity caused by corneal opacity. A massive DNA sequencing was conducted using a multigene panel associated with lipid metabolism disturbances. RESULTS AND GENETIC FINDINGS: Two likely pathogenic variants in LCAT were identified and later confirmed by Sanger sequencing. Both (c.491 G > A and c.496 G > A) were missense variants that originated an amino acid substitution (164Arginine for Histidine and 166Alanine for Threonine, respectively) modifying the protein sequence and its 3D structure. CONCLUSIONS: FLD and FED sharing common biochemical features, and the existence of other diseases with similar clinical profiles underline the need for a timely differential diagnosis aiming to address patients to preventive programs and future available therapies. This case, added to the reduced number of publications previously reported regarding FLD and FED, contributes to better understanding the genetic characteristics, clinical features, and diagnosis of these syndromes.

The role of oxidative stress in neurodegenerative diseases and potential antioxidant therapies.

Objectives: The central nervous system (CNS) is essential for homeostasis and controls the physiological functions of the body. However, the biochemical characteristics of the CNS make it especially vulnerable to oxidative damage (OS). This phenomenon compromises correct CNS functioning, leading to neurodegeneration and neuronal death. Contents: OS plays a crucial role in the physiopathology of neurodegenerative diseases. It is involved in multiple mechanisms of nucleic acid, protein, and lipid oxidation, thereby contributing to progressive brain damage. These mechanisms include mitochondrial dysfunction; excessive production of reactive oxygen and nitrogen species; deficiency of antioxidant defenses; protein oligomerization; cytokine production and inflammatory response; blood-brain barrier abnormalities; and proteasome dysfunction. All these dysfunctions are involved in the pathogenesis of neurodegenerative diseases, including Parkinson's disease, Alzheimer's disease, Huntington's disease, or amyotrophic lateral sclerosis. Summary and outlook: A curative treatment is currently not available. Research is focused on the search for therapies that reduce oxidative damage and delay disease progression. In the recent years, researchers have focused their attention on the effects of antioxidant therapies.

A study of crystalluria: effectiveness of including hygienic-dietary recommendations in laboratory reports.

Objectives: To assess the effectiveness of incorporating hygienic-dietary recommendations in laboratory reports in reducing the incidence of renal colic (RC). A study was performed to compare the incidence of RC in two groups of patients who had suffered at least a crystalluria event associated with the risk of urolithiasis. Recommendations were only incorporated in the laboratory reports of one group. Methods: A retrospective observational study. The study sample was composed of patients who had at least an episode of crystalluria associated with a higher risk of urolithiasis. The laboratory reports of patients in Group A (n=1,115), treated in 2017, did not include any hygienic-dietary recommendations, whereas patients in Group B (n=1,692), treated in 2018, received hygienic-dietary recommendations through their laboratory reports. χ2 and Mann-Whitney U test were used to assess differences based on sex, age, and type of urinary crystals. Results: The incidence of RC was 2.02 times higher in group A (2.24%) than in group B (1.12%). No significant differences were observed in the incidence of RC based on the type of urinary crystal. The incidence of RC was substantially higher in patients who suffered at least an event of crystalluria associated with a higher risk for urolithiasis as compared to the general population during the same period (0.46%, consistently with the incidence rates reported in the literature). Conclusions: The incorporation of messages alerting on the risk of urolithiasis and the inclusion of hygienic-dietary recommendations in laboratory reports may be useful for reducing the incidence of RC.

A novel variant in the COL4A3 gene: etiology of Alport syndrome type 2 in a 38-year-old male with suspected hereditary kidney disease.

Objectives: Patients with Alport syndrome develop progressive kidney function deterioration, sensorineural hearing loss, and ocular abnormalities. This condition is caused by mutations in COL4A5 (X-linked inheritance), COL4A3 and COL4A4 (autosomal dominant or recessive inheritance), and encoding type IV collagen α3, α4, and α5, respectively. If left untreated, clinical symptoms progress from microscopic hematuria to proteinuria, progressive kidney failure, and end-stage kidney disease. At present, kidney transplantation is the only effective approach. Next-generation sequencing is the method of choice for the diagnosis of this condition. Case presentation: We report the case of a young man with chronic kidney disease who eventually underwent transplantation. Molecular testing made it possible to determine the etiology of his clinical symptoms and autosomal recessive Alport syndrome type 2. The patient was found to be a compound heterozygote for two missense variants (trans configuration) in the COL4A3 gene: A likely pathogenic variant c.4981C>T (p.Arg1661Cys) in exon 52 inherited from the mother (described elsewhere), and another variant of uncertain significance, c.943G>A (p.Gly315Ser), in exon 17 inherited from the father that has not been previously reported in the literature or found in relevant databases. Conclusions: Following genetic confirmation, genetic counseling was provided to the patient and his direct relatives.

A variant of the gene HARS detected in the clinical exome: etiology of a peripheral neuropathy undiagnosed for 20 years.

Objectives: Describe a case with axonal Charcot-Marie-Tooth (CMT) type 2W, a neurological disease characterized by peripheral neuropathy typically involving the lower limbs and causing gait alterations and distal sensory-motor impairment. Case presentation: We report this case, where the application of massive genetic sequencing (NGS) with clinical exome in a molecular genetics laboratory enabled to detect the presence of candidate variants of the clinic of the patient. Conclusions: The variant detected in HARS gene suggests that this variant could be causative of the symptoms of the patient, who went undiagnosed for 20 years and experienced an exacerbation of symptoms over time.