👤 Raul Urrutia

Which phenotypes can be confidently linked to a genetic etiology in males with congenital hypogonadotropic hypogonadism (CHH) resulting in absent or arrested puberty? In this systematic review and reclassification of the disease-causing potential of gene variants using the recommendations of the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP), we found that absent or arrested puberty in males with CHH was linked to 93 genes, of which 29 were unequivocally disease-causing. The number of genes and phenotype characterizations associated with CHH in males has rapidly increased since the advent of next-generation sequencing technologies; however, the quality of the evidence for the interpretation of the causal relationship of gene variants is limited due to the lack of systematic criteria applied to the assessment of the pathogenic potential of the variants. We performed a systematic review of original articles indexed in PubMed until 5 October 2022 and using the search terms '(('hypogonadotropic hypogonadism' OR Kallmann) AND (sequencing OR mutation OR variant))' limited to 'Humans' and 'English'. After two investigators undertook the literature search independently, titles and abstracts of all records were reviewed by four of the authors to identify those articles to be included in the full-text review. Clinical data and the association with gene variants were extracted from males with delayed or arrested puberty due to CHH according to the article authors' criteria. Raw sequence variant information was used to reevaluate their pathogenic potential applying the ACMG/AMP guidelines for variant classification with InterVar. Subsequently, we considered the phenotype specificity criteria for sequence variant pathogenicity classification, based on curated genes associated with CHH, and classified patients into three categories: with monogenic disease-causing variants in genes associated with CHH, with variants in genes whose causality is unclear, and with variants that are not disease-causing. From a total of 1083 records, we included 245 publications with 775 male patients with CHH resulting in absent or arrested puberty, carrying 1001 variants in 93 genes. Gene variants were detected by Sanger sequencing in 61.8% of the cases and by next-generation sequencing (NGS) technologies in the rest. After variant reclassification of causality, 278 individuals were not considered to have a bona fide disease-causing gene variant, and 497 patients were reclassified as carrying at least one disease-causing variant associated with CHH. They carried 503 different disease-causing variants in 29 genes. Spontaneous puberty was absent in 85.5% and arrested in 14.5% of the 497 individuals with CHH carrying bona fide disease-causing variants. In males with absent puberty (complete hypogonadotrophic hypogonadism), FGFR1 and ANOS1 were the most frequently affected genes, accounting for 53.5% of the disease-causing variants. In males with incomplete spontaneous puberty (partial hypogonadotrophic hypogonadism), variants in FGFR1, NR0B1, and GNRHR were found in 70.3% of the cases. Micropenis, cryptorchidism and/or low testicular volume, considered 'red flags' for the diagnosis of CHH, were found in less than 30% of males, with cryptorchidism being more frequently observed in association with variants in FGFR1, ANOS1, KISS1R, SOX10, and GNRH1, and micropenis being more prevalent in patients with variants in TACR3, KISS1R, or GNRH1. Clinical manifestations in non-reproductive organs were found in 39.8% of the patients with bona fide disease-causing variants. Because we included studies going back to the initial genetic reports of patients with CHH, results obtained by Sanger sequencing represent a significant proportion of the whole sample, which may be biased by the use of a candidate gene strategy. A subanalysis of cases studied by NGS modified the results only slightly. This comprehensive synthesis will help clinicians in the guidance of reverse phenotyping once the precise genetic diagnosis is established, and researchers in the design of functional studies to clarify the role of specific sequence variants in the etiology of male CHH. A genetic etiology of CHH in males with absent or arrested puberty should be considered even in the absence of micropenis, cryptorchidism, and/or low testicular volume. This work was partially funded by grants PICT I-A-2018-02972 of Fondo de Promoción Científica y Técnica (FONCYT), PICT A-CAT III2021-73 of Fondo Argentino Sectorial (FONARSEC) and Proyectos de Redes Federales de Alto Impacto 2023 #3 of Ministerio de Ciencia, Tecnología e Innovación, Argentina. Competing interests: None declared. None declared. Show less

Maple syrup urine disease (MSUD) is a disorder of branched-chain amino acid metabolism caused by a defect in the branched-chain α-ketoacid dehydrogenase (BCKD) complex (OMIM #248600). The hallmark presentation is encephalopathic crisis in neonates, but can also present with metabolic decompensation, developmental delays, and feeding difficulties. Biochemical evidence for MSUD includes elevated branched-chain amino acids (BCAA) and the pathognomonic presence of alloisoleucine. The BCKD complex contains several subunits associated with autosomal recessive MSUD, while its regulatory proteins have less well-defined disease associations. We report on two families with the same Show less

Methods to increase the amount of omega-3 (n-3) PUFAs in milk are desirable for neonatal health. The n-3 PUFA, α-linolenic acid (18:3n-3), can be elongated to EPA (20:5n-3) and DHA (22:6n-3). n-6 PUFAs suppress tissue n-3 PUFA incorporation, but the effect of SFAs is not clear. In this study, we compared the effects of SFAs and n-6 PUFAs on n-3 PUFA incorporation into milk and tissues of lactating mice and tissues of their offspring. Female CD-1 mice were bred at 8 wk of age. All experimental diets included 3% flaxseed oil and were begun on day 8 of lactation: low-fat diet (LFD); high-SFA diet (SAT), with an additional 12% saturated oil; or high-linoleic-acid diet (HLA), with 12% high-linoleic-acid oil (% kcal, carbohydrates:fat:protein: LFD, 49:24:27; both SAT and HLA, 35:46:19; n = 5/treatment). After 5 d, pup stomach milk clot FA profiles, tissue FA profiles in dams and pups, and mammary and hepatic expression of lipid metabolism genes in dams were analyzed. Data were analyzed by ANOVA with treatment diet as a fixed effect. Dams in all groups had similar total milk fat concentrations, but both SAT and HLA decreased the concentration of n-3 PUFAs (SAT: -23%; HLA: -31%) compared with LFD, and HLA increased milk n-6 FAs by 347% compared with SAT. SAT pups had n-3 PUFA tissue concentrations similar to LFD, but HLA pups had lower n-3 PUFAs than SAT pups in multiple tissues (liver, -32%; kidney, -29%; heart, -28%; muscle, -18%). Mammary expression of lipid metabolism genes was mostly unchanged, but hepatic expression of elongases and desaturases was decreased with SAT compared with LFD [elongation of very-long-chain fatty acid (Elov)5, -42%; Elov6, -64%; fatty acid desaturase (Fads)1, -33%; Fads2, -44%]. HLA decreased n-3 PUFA concentrations across multiple pup tissues compared with SAT. This suggests that high dietary n-6 PUFAs suppress n-3 PUFA incorporation in neonates. Show less

This study examined the effect of linseed and algae on growth and carcass parameters, adipocyte cellularity, fatty acid profile and meat quality and gene expression in subcutaneous and intramuscular adipose tissues (AT) in lambs. After weaning, 33 lambs were fed three diets up to 26.7 ± 0.3 kg: Control diet (barley and soybean); L diet (barley, soybean and 10% linseed) and L-A diet (barley, soybean, 5% linseed and 3.89% algae). Lambs fed L-A diet showed lower average daily gain and greater slaughter age compared to Control and L (P < 0.001). Carcass traits were not affected by L and L-A diets, but a trend towards greater adipocyte diameter was observed in L and L-A in the subcutaneous AT (P = 0.057). Adding either linseed or linseed and algae increased α-linolenic acid and eicosapentaenoic acid contents in both AT (P < 0.001); however, docosahexaenoic acid was increased by L-A (P < 0.001). The n-6/n-3 ratio decreased in L and L-A (P < 0.001). Algae had adverse effects on meat quality, with greater lipid oxidation and reduced ratings for odor and flavor. The expression of lipogenic genes was downregulated in the subcutaneous AT (P < 0.05): acetyl-CoA carboxylase 1 (ACACA) in L and L-A and lipoprotein lipase (LPL) and stearoyl-CoA desaturase (SCD) in L-A. Fatty acid desaturase 1 (FADS1), fatty acid desaturase 2 (FADS2) and fatty acid elongase 5 (ELOVL5) were unaffected. In the subcutaneous AT, supplementing either L or L-A increased peroxisome proliferator-activated receptor gamma (PPARG) and CAAT-enhancer binding protein alpha (CEBPA) (P < 0.05), although it had no effect on sterol regulatory element-binding factor 1 (SREBF1). In the intramuscular AT, expression of ACACA, SCD, FADS1 and FADS2 decreased in L and L-A (P < 0.001) and LPL in L (P < 0.01), but PPARG, CEBPA and SREBF1 were unaffected. Show less