Severe polyhydramnios as neonatal presentation of Bartter’s syndrome type IV

Introduction: Bartter’s syndrome comprises a heterogeneous group of inherited salt-losing tubulopathies. There are two forms of clinical presentation: classical and neonatal, the most severe type. Types I and II account for most of the neonatal cases. Types III and V are usually less severe. Characteristically Bartter’s syndrome type IV is a saltlosing nephropathy with mild to severe neonatal symptoms, with a specific feature - sensorineural deafness. Bartter’s syndrome type IV is the least common of all recessive types of the disease. Description: the first reported case of a Portuguese child with neurosensorial deafness, polyuria, polydipsia and failure to thrive, born prematurely due to severe polyhydramnios, with the G47R mutation in the BSND gene that causes Bartter’s syndrome type IV. Discussion: there are few published cases of BS type IV due to this mutation and those reported mostly have moderate clinical manifestations which begin later in life. The poor phenotype-genotype relationship combined with the rarity of this syndrome usually precludes an antenatal diagnosis. In the presence of a severe polyhydramnios case, with no fetal malformation detected, normal karyotype and after maternal disease exclusion, autosomal recessive diseases, including tubulopathies, should always be suspected.

Natural human knockouts and Mendelian disorders: deep phenotyping in Italian isolates

Whole genome sequencing (WGS) allows the identification of human knockouts (HKOs), individuals in whom loss of function (LoF) variants disrupt both alleles of a given gene. HKOs are a valuable model for understanding the consequences of genes function loss. Naturally occurring biallelic LoF variants tend to be significantly enriched in “genetic isolates,” making these populations specifically suited for HKO studies. In this work, a meticulous WGS data analysis combined with an in-depth phenotypic assessment of 947 individuals from three Italian genetic isolates led to the identification of ten biallelic LoF variants in ten OMIM genes associated with known autosomal recessive diseases. Notably, only a minority of the identified HKOs (C7, F12, and GPR68 genes) displayed the expected phenotype. For most of the genes, instead, (ACADSB, FANCL, GRK1, LGI4, MPO, PGAM2, and RP1L1), the carriers showed none or few of the signs and symptoms typically associated with the related diseases. Of particular interest is a case presenting with a FANCL biallelic LoF variant and a positive diepoxybutane test but lacking a full Fanconi anemia phenotypic spectrum. Identifying KO subjects displaying expected phenotypes suggests that the lack of correct genetic diagnoses may lead to inappropriate and delayed treatment. In contrast, the presence of HKOs with phenotypes deviating from the expected patterns underlines how LoF variants may be responsible for broader phenotypic spectra. Overall, these results highlight the importance of in-depth phenotypical characterization to understand the role of LoF variants and the advantage of studying these variants in genetic isolates.

Assessment of role of consanguinity in formation of cleft lip and cleft palate

Consanguinity is considered a significant factor in autosomal recessive diseases; it has also been associated with congenital anomalies such as hydrocephalus, polydactilia and Cleft Lip and Palate deformities. The risk of congenital conditions is higher in subjects born of first degree consanguineous parents compared with those of non-consanguineous marriages. The aim of this study is to evaluate the prevalence of consanguinity with formation of cleft lip/ cleft palate formation in Tamil, Telugu population. This is a retrospective study. The details of 86,000 patient records were reviewed and analysed, out of which 76 patients who had undergone surgical treatment for cleft lip and cleft palate deformities between June 2019 to march 2020 were included in this study. The details like age, gender, family history and cleft diagnosis were evaluated and entered in SPSS and analysed through a chi-square test. It was observed that 11% of patients reported with history of consanguineous marriages which was associated with formation of cleft lip/palate. Within the limits of the study, it was concluded that consanguinity had a significant role in formation of cleft lip/cleft palate.

Autonomous decisions by couples in reproductive care

Background Preconception Expanded Carrier Screening (ECS) is a genetic test offered to a general population or to couples who have no known risk of recessive and X-linked genetic diseases and are interested in becoming parents. A test may screen for carrier status of several autosomal recessive diseases at one go. Such a program has been piloted in the Netherlands and may become a reality in more European countries in the future. The ethical rationale for such tests is that they enhance reproductive autonomy. The dominant conception of autonomy is individual-based. However, at the clinic, people deciding on preconception ECS will be counselled together and are expected to make a joint decision, as a couple. The aim of the present study was to develop an understanding of autonomous decisions made by couples in the context of reproductive technologies in general and of preconception ECS in particular. Further, to shed light on what occurs in reproductive clinics and suggest concrete implications for healthcare professionals. Main text Based on the shift in emphasis from individual autonomy to relational autonomy, a notion of couple autonomy was suggested and some features of this concept were outlined. First, that both partners are individually autonomous and that the decision is reached through a communicative process. In this process each partner should feel free to express his or her concerns and preferences, so no one partner dominates the discussion. Further, there should be adequate time for the couple to negotiate possible differences and conclude that the decision is right for them. The final decision should be reached through consensus of both partners without coercion, manipulation or miscommunication. Through concrete examples, the suggested notion of couple autonomy was applied to diverse clinical situations. Conclusions A notion of couple autonomy can be fruitful for healthcare professionals by structuring their attention to and support of a couple who is required to make an autonomous joint decision concerning preconception ECS. A normative implication for healthcare staff is to allow the necessary time for decision-making and to promote a dialogue that can increase the power of the weaker part in a relationship.

Wilson disease: early screening for better living

Autosomal recessive diseases are more common among consanguineous marriages noted particularly in southern parts of India. There is a gradual increase in the genome wide homogenecity with the increasing levels of consanguinity. Here we are reporting a case series of such an autosomal recessive condition, namely Wilson Disease (WD), where three children were affected with the disease, who were born out of consanguineous marriages. The first case presented with neuropsychiatric manifestations, the second case and third cases were diagnosed through screening of family members leading to earlier identification of the disease. In these cases consanguinity has been emphasised as the major predisposing factor leading to their manifestations. This case series highlights the importance of screening the other family members of the index case. Conditions such as Wilson disease have an excellent prognosis if pharmacotherapy is initiated appropriately.

CNTNAP1 Mutations and Their Clinical Presentations: New Case Report and Systematic Review

Lethal congenital contracture syndrome type 7 (LCCS7) and congenital hypomyelinating neuropathy type 3 (CHN3) are rare autosomal recessive diseases, characterized by severe neonatal hypotonia, polyhydramnios, arthrogryposis, facial diplegia, and severe motor paralysis, leading to death in early infancy. They are related to mutations in the CNTNAP1 (contactin associated protein 1) gene, playing an important role in myelination. Recent studies have shown that both diseases could present with a wide phenotypic spectrum, with promising survival up to early childhood. We report on a 7-year-old boy from a nonconsanguineous Lebanese family presenting with neonatal hypotonia, respiratory distress, and arthrogryposis. Molecular analysis revealed the presence of a pathogenic variant in the CNTNAP1 gene leading to a premature stop codon: NM_003632.2:c.3361C>T p.(Arg1121∗). A review of the literature is discussed.

Cystic fibrosis carriers are at increased risk for a wide range of cystic fibrosis-related conditions

Autosomal recessive diseases, such as cystic fibrosis (CF), require inheritance of 2 mutated genes. However, some studies indicate that CF carriers are at increased risk for some conditions associated with CF. These investigations focused on single conditions and included small numbers of subjects. Our goal was to determine whether CF carriers are at increased risk for a range of CF-related conditions. Using the Truven Health MarketScan Commercial Claims database (2001–2017), we performed a population-based retrospective matched-cohort study. We identified 19,802 CF carriers and matched each carrier with 5 controls. The prevalence of 59 CF-related diagnostic conditions was evaluated in each cohort. Odds ratios for each condition were computed for CF carriers relative to controls. All 59 CF-related conditions were more prevalent among carriers compared with controls, with significantly increased risk (P < 0.05) for 57 conditions. Risk was increased for some conditions previously linked to CF carriers (e.g., pancreatitis, male infertility, bronchiectasis), as well as some conditions not previously reported (e.g., diabetes, constipation, cholelithiasis, short stature, failure to thrive). We compared our results with 23,557 subjects with CF, who were also matched with controls; as the relative odds of a given condition increased among subjects with CF, so did the corresponding relative odds for carriers (P < 0.001). Although individual-level risk remained low for most conditions, because there are more than 10 million carriers in the US, population-level morbidity attributable to the CF carrier state is likely substantial. Genetic testing may inform prevention, diagnosis, and treatment for a broad range of CF carrier-related conditions.

Hardy-Weinberg Equilibrium in the Large Scale Genomic Sequencing Era

Hardy-Weinberg Equilibrium (HWE) is used to estimate the number of homozygous and heterozygous variant carriers based on its allele frequency in populations that are not evolving. Previously, deviation from HWE in large population databases were investigated to detect genotyping errors, which can result in extreme heterozygote excess (HetExc). However, HetExc might also be a sign of natural selection since recessive disease causing variants are expected to occur less frequently in a homozygous state in the general population, but might reach high allele frequency, especially if they are advantageous, in a heterozygote state. We developed a filtering strategy to detect these variants and applied it on genome data from 137,842 individuals. We found that the main limitations of this approach were quality of genotype calls and insufficient population sizes, whereas population structure and high level of inbreeding could reduce sensitivity, but not precision, in certain populations. Nevertheless, we identified 365 HetExc variants in 326 genes, most of which were specific to African/African American populations (~84.7%). Although the majority of them were not associated with known diseases, or were classified as “benign”, they were enriched in genes associated with autosomal recessive diseases. The resulting dataset also contained two known recessive disease causing variants with evidence of heterozygote advantage in the genes HBB and CFTR. Finally, we provide in silico evidence of a novel heterozygote advantageous variant in the CHD6 gene (involved in influenza virus replication). We anticipate that our approach will allow the detection of rare recessive disease causing variants in the future.

Determination of the carrier frequency of mutations in the CFTR, PAH, GALT and GJB2 genes among 2168 individuals without clinical signs of hereditary diseases

Цель: оценка частоты гетерозиготного носительства мутаций в генах CFTR, PAH, GALT и GJB2 среди здоровых индивидов. Материалы и методы. В исследовании принимали участие 1000 доноров крови, проживающих в Москве и 1168 сотрудников ФГБУ «НМИЦ АГП им. В.И. Кулакова», проживающих в Москве и Московской области. У всех участников исследования отсутствовали клинические проявления наследственных заболеваний. Молекулярно-генетическое исследование образцов проводили путём анализа наиболее частых мутаций в генах CFTR, PAH, GALT и GJB2 с применением технологии real-time PCR Результаты. При генотипировании были выявлены 46 носителей мутаций в гене CFTR, 63 носителя мутаций в гене PAH, 12 носителей мутаций в гене GALT и 74 носителя мутации в гене GJB2. Кроме того, в 3 случаях было установлено сочетанное носительство мутаций: CFTR: F508del + GALT:Q188R; CFTR:dele2,3 (21kb) + GJB2:35delG; GJB2:35delG + GALT:Q188R. Выводы. Полученные данные свидетельствуют о высокой частоте носительства мутаций в исследуемых генах в обследованной выборке. Таким образом, имеются предпосылки для диагностики носительства мутаций, приводящих к наиболее частым аутосомно-рецессивным заболеваниям в популяции. Подобные исследования могут стать эффективным инструментом для профилактики наследственной патологии в семьях носителей мутаций. The study aim was to assess the frequency of heterozygous carriage of mutations in the CFTR, PAH, GALT, and GJB2 genes among healthy individuals. Materials and methods. The study involved 1000 blood donors living in Moscow and 1168 employees of the FSBI Research center for obstetrics gynecology and perinatology MOH Russia, living in Moscow and the Moscow region. All participants in the study did not have clinical manifestations of hereditary diseases. Molecular genetic studies of the samples were carried out by analyzing the most frequent mutations in the CFTR, PAH, GALT and GJB2 genes, using real-time PCR technology Results. 46 carriers of mutations in the CFTR gene, 63 carriers of mutations in the PAH gene, 12 carriers of mutations in the GALT ge ne and 74 carriers of mutations in the GJB2 gene were identified. In addition, in 3 cases, a combined carriage of mutations was found: CFTR: F508del + GALT: Q188R; CFTR: dele2.3 (21kb) + GJB2: 35delG; GJB2: 35delG + GALT: Q188R. Conclusion. The data obtained indicate a fairly high level of carriage of the studied diseases. Thus, there are prerequisites and opportunities for diagnosing the carriage of the most common autosomal recessive diseases in the population. Such studies can be an effective tool for the prevention of hereditary pathologies and reduce the incidence of diseases.