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Lamia K Alshamlani,1 Dana S Alsulaim,1 Raghad S Alabbad,1 Ahad A Alhoshan,1 Joud F Alkhoder,1 Norah S Alsaleh,2 Mohammed Almannai,1– 3 Faroug Ababneh,2 Manal Algattan,4 Lojain Alsini,4 Abdulrahman Faiz Alswaid,2 Wafaa M Eyaid,1– 3 Fuad Al Mutairi,1– 3 Muhammad Umair,3 Majid Alfadhel1– 3 1College of Medicine, King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), King Abdulaziz Medical City, Ministry of National Guard Health Affairs (MNG-HA), Riyadh, Saudi Arabia; 2Genetics and Precision Medicine Department (GPM), King Abdullah Specialized Children Hospital (KASCH), King Saud Bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard Health Affairs (MNG-HA), Riyadh, Saudi Arabia; 3Medical Genomics Research Department, King Abdullah International Medical Research Center (KAIMRC), King Saud Bin Abdulaziz University for Health Sciences, Ministry of National Guard Health Affairs (MNGH), Riyadh, Saudi Arabia; 4Pathology and Laboratory Medicine Department, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi ArabiaCorrespondence: Majid Alfadhel, Genetics and Precision Medicine Department (GPM), King Abdullah Specialized Children’s Hospital, King Abdulaziz Medical City, P.O Box 22490, Riyadh, 11426, Saudi Arabia, Tel +00 966 11 805 3560, Fax +00 966 11 805 5555, Email dralfadhelm@gmail.comBackground: Consanguinity, or the practice of marrying close relatives, is a common cultural tradition in Saudi Arabia, with rates among the highest in the world. This practice has significant implications for the prevalence and distribution of major single genetic defects and chromosomal abnormalities within the Saudi population.Methods: Herein, using the BESTCare electronic medical record system (designed to streamline hospital operations, enhance patient care, and improve the overall efficiency of healthcare services; bestcare.ezcaretech.com) in a single tertiary centre, King Abdullah Specialized Children Hospital (KASCH) in Riyadh, Saudi Arabia, we performed a cross-sectional study for all patients referred to the hospital from the 1st January 2020 until 1st January 2022.Results: The present study, which included 1100 individuals, found a high prevalence of consanguinity (64%) and a significant proportion of third-degree relatives (69%). The mean age of participants was 12.24 years, and the diagnostic rate using advanced molecular genetics techniques was 45%, with whole exome sequencing (WES) being the most common method (43%). The study also noted a significant delay in diagnosis for more than a year in 16% of cases, with a common neurodevelopmental phenotype (18%).Conclusion: In conclusion, we revealed the prevalence of consanguineous marriages in the KASCH hospital in Riyadh, Saudi Arabia. We also highlighted the most frequently referred phenotype. These findings are consistent with previous research on the prevalence and impact of consanguinity on rare genetic disorders.Keywords: consanguinity, genetic disorders, autosomal recessive disorders, Saudi Arabia, prevalence of single gene disorder, chromosomal abnormalities

Background: Rare genetic disorders may result in death before a definitive clinical diagnosis is established. Aim: This study aims to outline the processes and challenges in managing, from a genetic perspective, couples who lost children affected by rare genetic disorders. Results: Six couples who experienced child loss due to rare genetic disorders, seen by the primary author at genetic evaluation and counseling sessions, were retrospectively analyzed. Four out of 6 couples reported consanguinity. Exome and genome sequencing were performed for the parents. Carrier status of two rare lethal metabolic disorders was confirmed in one consanguineous couple. Three couples were carriers of 3 other rare diseases. Variants of LYST, MPV17, HEXB, ITGB4, CD3E, ASPM, TK2, COL11A2, and LAMB3 genes were identified. Six out of 10 were pathogenic variants, out of which 4 correlated with the demised children’s phenotypes. One couple was negative for pathogenic variants. The last couple did not undergo genetic testing since they were beyond the fertile window. Conclusion: Appropriate parental genetic evaluation and counseling are mandatory for selecting the right genetic test to certify the diagnosis postmortem, by virtue of molecular autopsy by proxy. Clarifying a rare disorder diagnosis can help couples to avoid recurrence and plan early for their next pregnancies. [ABSTRACT FROM AUTHOR]

Coronavirus disease 19 (COVID-19) is an infectious disease caused by severe acute respiratory coronavirus 2 (SARS-CoV-2) causing acute systemic disorders and multi-organ damage. β-thalassemia (β-T) is an autosomal recessive disorder leading to the development of anemia. β-T may lead to complications such as immunological disorders, iron overload, oxidative stress, and endocrinopathy. β-T and associated complications may increase the risk of SARS-CoV-2, as inflammatory disturbances and oxidative stress disorders are linked with COVID-19. Therefore, the objective of the present review was to elucidate the potential link between β-T and COVID-19 regarding the underlying comorbidities. The present review showed that most of the β-T patients with COVID-19 revealed mild to moderate clinical features, and β-T may not be linked with Covid-19 severity. Though patients with transfusion-dependent β-T (TDT) develop less COVID-19 severity compared to non-transfusion-depend β-T(NTDT), preclinical and clinical studies are recommended in this regard. [ABSTRACT FROM AUTHOR]

Abstract The common autosomal recessive (AR) mutation carrier is still unknown in Vietnam. This study aims to identify the most common AR gene mutation carriers in women of reproductive age to build a Vietnamese-specific carrier screening panel for AR and X-linked disorders in the preconception and prenatal healthcare program. A cross-sectional study was conducted at University Medical Center–Branch 2 in Ho Chi Minh City from December 1st, 2020, to June 30th, 2023. 338 women have consented to take a 5 mL blood test to identify 540 recessive genes. The carrier screening panel was designed based on the American College of Medical Genetics and Genomics (ACMG)-recommended genes and suggestions from 104 clinical experts in Vietnam. Obstetricians and genetic experts counseled all positive testing results to discuss the possibility of recessive diseases in their offspring. The most common recessive disorders were defined at a prevalence of 1 in 60 or greater, and those were added to a Vietnamese-specific carrier screening panel. 338 non-pregnant and pregnant women underwent the expanded carrier screening (ECS). The carrier frequency was 63.6%, in which 215 women carried at least one AR gene mutation. GJB2 hearing impairment was identified as the most common chronic condition (1 in 5). The second most common AR disorder was beta-thalassemia (1 in 16), followed by cystic fibrosis (1 in 23), G6PD deficiency (1 in 28), Wilson’s disease (1 in 31), Usher’s syndrome (1 in 31), and glycogen storage disease (1 in 56). Seven common recessive genes were added in ethnic-based carrier screening. Women in the South of Vietnam have been carried for many recessive conditions at high frequency, such as hearing impairment, genetic anemia, and cystic fibrosis. It is necessary to implement a preconception and prenatal screening program by using seven widely popular AR genes in a Vietnamese-specific carrier screening panel to reduce the burden related to AR and X-linked disorders.

BackgroundRare genetic disorders may result in death before a definitive clinical diagnosis is established.AimThis study aims to outline the processes and challenges in managing, from a genetic perspective, couples who lost children affected by rare genetic disorders.ResultsSix couples who experienced child loss due to rare genetic disorders, seen by the primary author at genetic evaluation and counseling sessions, were retrospectively analyzed. Four out of 6 couples reported consanguinity. Exome and genome sequencing were performed for the parents. Carrier status of two rare lethal metabolic disorders was confirmed in one consanguineous couple. Three couples were carriers of 3 other rare diseases. Variants of LYST, MPV17, HEXB, ITGB4, CD3E, ASPM, TK2, COL11A2, and LAMB3 genes were identified. Six out of 10 were pathogenic variants, out of which 4 correlated with the demised children’s phenotypes. One couple was negative for pathogenic variants. The last couple did not undergo genetic testing since they were beyond the fertile window.ConclusionAppropriate parental genetic evaluation and counseling are mandatory for selecting the right genetic test to certify the diagnosis postmortem, by virtue of molecular autopsy by proxy. Clarifying a rare disorder diagnosis can help couples to avoid recurrence and plan early for their next pregnancies.

Cystic fibrosis, phenylketonuria, alpha-1 antitrypsin deficiency, and sensorineural hearing loss are among the most common autosomal recessive diseases, which require carrier screening. The evaluation of population allele frequencies (AF) of pathogenic variants in genes associated with these conditions and the choice of the best genotyping method are the necessary steps toward development and practical implementation of carrier-screening programs. We performed custom panel genotyping of 3821 unrelated participants from two Russian population representative samples and three patient groups using real-time polymerase chain reaction (PCR) and next generation sequencing (NGS). The custom panel included 115 known pathogenic variants in the CFTR, PAH, SERPINA1, and GJB2 genes. Overall, 38 variants were detected. The comparison of genotyping platforms revealed the following advantages of real-time PCR: relatively low cost, simple genotyping data analysis, and easier detection of large indels, while NGS showed better accuracy of variants identification and capability for detection of additional pathogenic variants in adjacent regions. A total of 23 variants had significant differences in estimated AF comparing with non-Finnish Europeans from gnomAD. This study provides new AF data for variants associated with the studied disorders and the comparison of genotyping methods for carrier screening. [ABSTRACT FROM AUTHOR]

For the efficient diagnosis of rare and undiagnosed diseases, the parallel detection of copy number variants (CNVs) and single nucleotide variants using exome analysis is required. Recently, our group reported the usefulness of a program called EXCAVATOR2, which screens for CNVs from aligned exome data in bam format. This method is expected to contribute to the identification of structural variants and to improve the diagnosis rate, especially for the diagnosis of autosomal recessive disease, when a conventional exome analysis identifies a pathogenic variant in one allele but not the other. Here we report a 2‐year‐old Japanese boy with an undiagnosed disease. He had severe neonatal asphyxia, severe intellectual disability, intractable seizures, cerebellar and brainstem hypoplasia and dysmorphic features including a prominent supraorbital ridge, thin upper lip, and prominent antihelix. An exome analysis reinforced with a copy number analysis using the EXCAVATOR2 method revealed that the patient had a hemizygous variant in chr2(GRCh37):g.130925108G>A, NM_017951.4 c.832C>T, p.(Arg278*) in SMPD4 that was derived from his father and a deletion of SMPD4 derived from his mother. The presence of the deletion spanning SMPD4 was confirmed by short‐read and long‐read whole‐genome sequencing. The successful diagnosis of this reported patient demonstrates the diagnostic utility of EXCAVATOR2 and overcomes the weakness of exome analysis for the detection of autosomal recessive diseases in nonconsanguineous families, significantly impacting genetic counseling for family planning. [ABSTRACT FROM AUTHOR]

The number and distribution of recessive alleles in the population for various diseases are not known at genome-wide-scale. Based on 6,447 exome sequences of healthy, genetically unrelated Europeans of two distinct ancestries, we estimate that every individual is a carrier of at least 2 pathogenic variants in currently known autosomal-recessive (AR) genes and that 0.8%–1% of European couples are at risk of having a child affected with a severe AR genetic disorder. This risk is 16.5-fold higher for first cousins but is significantly more increased for skeletal disorders and intellectual disabilities due to their distinct genetic architecture. [ABSTRACT FROM AUTHOR]

Homozygous mutations in the lipopolysaccharide-responsive vesicle trafficking, beach- and anchor-containing ( LRBA ) gene lead to a syndrome characterized by early-onset hypogammaglobulinemia, autoimmunity, lymphoproliferation, and inflammatory bowel disease. This report describes a 10-year-old female who experienced three seizure episodes, including two generalized tonic-clonic seizures (GTCS) and one focal seizure, alongside septic shock. The patient had a history of recurrent respiratory tract infections, inflammatory bowel disease, multiple blood transfusions, lymphadenopathy, significant organomegaly, and hematological abnormalities, all consistent with an LRBA deficiency. This case highlights the critical need for prompt recognition and identification of LRBA gene mutations to enable timely management and improve patient outcomes., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Dua et al.)

The clotting pathway involves intrinsic and extrinsic pathways converging into a common pathway. These pathways require activated factors that sequentially convert prothrombin to thrombin, which then converts fibrinogen to fibrin, forming a stable clot. Clotting factor deficiency impairs this cascade leading to excessive bleeding or bruising due to insufficient clot formation. Here, we present the case of a 47-year-old female who initially complained of epigastric pain. By the third day of admission, she experienced four to five episodes of bleeding gums, resulting in a blood loss of approximately 300 mL. The patient exhibited abnormal prothrombin time (PT) and international normalized ratio (INR) values, leading to a diagnosis of Factor X (FX) deficiency upon further evaluation. This case report emphasizes the need to diagnose coagulopathies such as FX deficiency and how early diagnosis will help not only in patient care and management but also in screening family members who may be affected., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Chaudhary et al.)

The etiology of hereditary tyrosinemia type 1 (HT-1) is the absence of fumarylacetoacetate hydrolase (FAH), an enzyme that catalyzes the last stage of the tyrosine breakdown process. With an autosomal recessive inheritance pattern, it is an uncommon genetic condition. We present a case of HT-1 in a three-year-old female child characterized by abdominal distension, facial edema, lower limb edema, and an enlarged liver with parenchymal disease. A liver biopsy confirmed mixed nodular cirrhosis, and a subsequent whole exome sequencing revealed autosomal recessive inheritance of tyrosinemia type 1. The patient is currently undergoing treatment with capsule nitisinone 5 mg, which inhibits the second step of tyrosine degradation to prevent tyrosinemia, along with a restricted protein diet, while awaiting liver transplantation., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Ilyaz et al.)

Introduction Pyruvate kinase deficiency (PKD) is a rare autosomal recessive disorder characterized by mutations in the PKLR gene, causing impaired glycolysis in red blood cells and leading to diverse clinical manifestations. The prevalence of PKD in Saudi Arabia remains understudied, particularly in the context of consanguinity and non-specialized medical facilities. Methods We conducted a retrospective analysis of seven PKD patients of Arab ethnicity, focusing on demographics, medical history, clinical features, laboratory results, treatments, and outcomes. Results Our patient cohort comprised five males and two females, aged 10 to 38 years, of Arab ethnicity. Consanguinity was prevalent, and hereditary connections were identified in five patients. PKD exhibited varying clinical presentations, with early-onset symptoms including neonatal jaundice and symptomatic anemia. One patient experienced severe hepatic disease progression leading to multiorgan failure. Blood transfusions were universally required, indicating the severity of the disorder. Anemia severity varied among patients, with diverse hematological irregularities. Splenectomy was performed for most patients, improving hemoglobin levels and transfusion needs in some cases. Iron chelation was administered, although iron overload persisted. Thrombocytosis and venous thromboembolism were observed post splenectomy. Jaundice and gallstones were common, leading to cholecystectomy. Laboratory findings remained consistent, with heightened reticulocyte counts and altered enzyme levels. Discussion PKD is a rare disorder characterized by diverse clinical manifestations. Prevalence estimation is complex due to various factors, and its diagnosis is challenged by clinical similarities with other disorders. Our cohort exhibited a spectrum of complications, highlighting the necessity for tailored interventions. Iron overload remained a concern, necessitating continuous monitoring. Although endocrine disorders and osteoporosis were absent in our cohort, vigilance is essential due to the disease's progressive nature. Genetic factors were prominent, supporting the genetic basis of PKD. Splenectomy improved anemia but had a limited impact on gallstones. Iron overload management and bone health remain crucial considerations. Conclusion This study offers comprehensive insights into the clinical and demographic characteristics of PKD patients, illustrating the complex nature of the disorder. The findings underscore the need for personalized management strategies and vigilant monitoring to address the diverse clinical manifestations and challenges associated with PKD., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Nasiri et al.)

Background: Acid sphingomyelinase deficiency (ASMD) is a rare group of autosomal recessive disorders. This report provides the first detailed description of the periodontal condition and treatment response in a patient with chronic visceral ASMD. Case description: A 49‐year‐old white woman with ASMD showed elevated visible plaque index (VPI), gingival bleeding index (GBI), and bleeding on probing (BOP) at 100% of sites. Periodontal pocket depths (PPD) were mostly shallow to moderate (at 96% of sites), whereas the loss of clinical attachment (CAL) was moderate to severe (54% and 46% of sites, respectively, at 4‐6 mm and ≥7 mm categories). Periapical radiographs revealed the presence of furcation involvement and intra‐bony defects. The periodontal diagnosis was periodontitis stage IV, generalized, grade C. Ninety days after the end of the supra and subgingival control (e.g., cause‐related therapy), marked reduction was observed for all periodontal indicators: VPI (‐83%), GBI (‐79%), BOP (‐85%), elimination of sites PPD ≥7 mm, 27% increase in sites PPD 1‐3 mm (from 64% to 91%), and gain of clinical attachment (gain of 11% CAL 1‐3 mm and 25% CAL 4‐6 mm; and a reduction of 36% CAL ≥7 mm). Practical implications: Despite the severity of the initial periodontal condition, the patient with chronic visceral ASMD responded well to the non‐surgical periodontal treatment. [ABSTRACT FROM AUTHOR]

Prader–Willi syndrome (PWS) is a prototypic genetic condition related to imprinting. Causative mechanisms include paternal 15q11‐q13 deletion, maternal chromosome 15 uniparental disomy (UPD15), Prader–Willi Syndrome/Angelman Syndrome (PWS/AS) critical region imprinting defects, and complex chromosomal rearrangements. Maternal UPD15‐related PWS poses risks of concomitant autosomal recessive (AR) disorders when the mother carries a pathogenic variant in one of the genes on chromosome 15 associated with autosomal recessive inherited disease. Co‐occurrence of autosomal recessive conditions in the setting of UPD leads to increased complexity of the clinical phenotype, and may delay the diagnosis of PWS. We report a patient with PWS and associated congenital ichthyosis due to maternal UPD15, and a homozygous novel pathogenic variant in ceramide synthase 3 (CERS3). We also review the literature of associated disorders reported in the setting of maternal UPD15‐related PWS and provide a summary of the previously described CERS3 variants. This represents the second case of autosomal recessive congenital ichthyosis (ARCI) in the setting of PWS and UPD15. There needs to be a high index of suspicion of this genetic mechanism when there is unexpected phenotype or evolution of the clinical course in a patient with PWS. [ABSTRACT FROM AUTHOR]

Seckel syndrome, also commonly called Seckel dwarfism, is a rare congenital disorder and always associated with severe growth retardation in utero . This retarded growth lingers on and causes serious developmental deformities ensuing to short stature, microcephaly, mental retardation, and a beak-like nose. This case report intends to present an interesting case of a 14-year-old female patient with various clinical manifestations, typical radiographic features, and characteristic dental manifestations correlated with the literature. A detailed understanding of the present case would assist pediatric dentists in correct and prompt diagnosis, precise treatment, and the prevention of severe consequences caused by Seckel syndrome., How to Cite This Article: Tatiya N, Kesri R, Ukey A. Seckel Dwarfism-A Rare Autosomal Recessive Inherited Syndrome: A Case Report. Int J Clin Pediatr Dent 2024;17(2):211-215., Competing Interests: Source of support: Nil Conflict of interest: None Patient consent statement: The author(s) have obtained written informed consent from the patient's parents/legal guardians for publication of the case report details and related images., (Copyright © 2024; The Author(s).)

Patients with autosomal recessive (AR) disorders are usually born to parents both of whom are heterozygous carriers of the disease. However, in some instances only one of the parents is a carrier and a mutation is segregated to the patient through uniparental isodisomy (UPiD). Recently, an increasing number of such case reports has been published, and it has become clear that there are several different UPiD patterns that cause AR disorders. In this article, we report 3 remarkable patients with different patterns of UPiD. We then review 85 cases collected in the literature. We realized that they can be classified into 3 patterns: UPiD of the whole chromosome, segmental UPiD with uniparental heterodisomy (UPhD), and segmental UPiD caused by post-zygotic mitotic recombination (MiRe). Whole chromosomal UPiD accounted for the majority of cases, with paternal origin accounting for approximately twice as many cases as maternal origin. Most cases of segmental UPiD with UPhD were of maternal origin, with a dominancy of nondisjunction in meiosis I, while segmental UPiD through MiRe is the smallest pattern with equal parental origin. These differences in proportion and parental origin in each pattern can be explained by considering nondisjunction during oogenesis as the starting point and UPiD as subsequent events. [ABSTRACT FROM AUTHOR]

Congenital adrenal hyperplasia due to 21‐hydroxylase deficiency (21OHD‐CAH) is an autosomal recessive disorder affecting steroidogenesis, due to mutations in CYP21A2 (6p21.3). 21OHD‐CAH neonatal screening is based on 17‐hydroxyprogesterone (17OHP) serum levels, showing high type I error rate and low sensitivity to mild CAH forms. Here, we used an epidemiological approach, which estimates the allelic frequency (q) of an autosomal recessive disorder using the proportion of homozygous patients, the mutational spectrum and the inbreeding coefficient in a sample of affected individuals. We applied this approach to 2 independent Italian cohorts of patients with both clinical and molecular diagnosis of 21OHD‐CAH from mainland Italy (N = 240) and Sardinia (N = 53). We inferred q estimates of 2.87% and 1.83%, corresponding to a prevalence of 1/1214 and 1/2986, respectively. CYP21A2 mutational spectra were quite discrepant between the 2 cohorts, with V281L representing 74% of all the mutations detected in Sardinia vs 37% in mainland Italy. These findings provide an updated fine‐grained picture of 21OHD‐CAH genetic epidemiology in Italy and suggest the need for a screening approach suitable to the detection of the largest number of clinically significant forms of CAH. [ABSTRACT FROM AUTHOR]

Consanguineous marriage is common among the South Asian heritage community in the UK. While conferring social and cultural benefits, consanguinity is associated with an increased risk of autosomal recessive disorders and an increase in childhood death and disability. We have previously developed a genetic service to address the needs of this community. We report the extension of this service to include community-based initiatives aimed at promoting understanding of genetic issues related to consanguinity and improving access to genetic services. Our approach was to develop integrated clinical, educational and community engagement initiatives that would be sustainable on a long-term basis. The service provided for South Asian families by a specialist genetic counsellor was extended, and a series of genetics education and awareness sessions were provided for a diverse range of frontline healthcare workers. Two community genetic outreach worker posts were established to facilitate the engagement of the local South Asian population with genetics. The education and awareness sessions helped address the lack of genetic knowledge among primary health care professionals and community workers. Engagement initiatives by the genetic outreach worker raised awareness of genetic issues in the South Asian community and families affected by autosomal recessive disorders. All three elements of the extended service generated positive feedback. A three-stranded approach to addressing the needs of consanguineous families affected by autosomal recessive disorders as recommended by the World Health Organisation is suggested to be an acceptable, effective and sustainable approach to delivery of service in the UK. [ABSTRACT FROM AUTHOR]

In a genetically isolated community in the Netherlands four severe recessive genetic disorders occur at relatively high frequency (pontocerebellar hypoplasia type 2 (PCH2), fetal akinesia deformation sequence (FADS), rhizomelic chondrodysplasia punctata type 1 (RCDP1), and osteogenesis imperfecta (OI) type IIB/III. Over the past decades multiple patients with these disorders have been identified. This warranted the start of a preconception outpatient clinic, in 2012, aimed at couples planning a pregnancy. The aim of our study was to evaluate the offer of targeted genetic carrier screening as a method to identify high-risk couples for having affected offspring in this high-risk subpopulation. In one year, 203 individuals (92 couples and 19 individuals) were counseled. In total, 65 of 196 (33.2%) tested individuals were carriers of at least one disease, five (7.7%) of them being carriers of two diseases. Carrier frequencies of PCH2, FADS, RCDP1, and OI were 14.3%, 11.2%, 6.1%, and 4.1% respectively. In individuals with a positive family history for one of the diseases, the carrier frequency was 57.8%; for those with a negative family history this was 25.8%. Four PCH2 carrier-couples were identified. Thus, targeted (preconception) carrier screening in this genetically isolated population in which a high prevalence of specific disorders occurs detects a high number of carriers, and is likely to be more effective compared to cascade genetic testing. Our findings and set-up can be seen as a model for carrier screening in other high-risk subpopulations and contributes to the discussion about the way carrier screening can be offered and organized in the general population. [ABSTRACT FROM AUTHOR]

Consanguinity is one of the most frequent risk factors for congenital disorders. In theory, prospective exome sequencing of consanguineous couples could identify couples who both are carriers of autosomal recessive diseases, and empower such couples to make informed reproductive decisions. To investigate this, we sent blood samples to our laboratory of four pairs of consanguineous parents having one or more children affected by an autosomal recessive disorder, without revealing any diagnostic information. The study was restricted to find identical, previously described, or evidently pathogenic mutations in both parents of each couple, in over 400 genes known to result in severe autosomal recessive disorders. Out of the six autosomal recessive disorders known to the four couples studied, two were correctly identified. Carrier status of one not previously known autosomal recessive disorder was discovered. As expected, given the pipeline used, large deletions, mutations in genes not present in the gene list, mutations outside the exons and consensus splice sites, and mutations that were not evidently pathogenic and previously not reported, were not identified. The restriction to detecting only couples with identical mutations diminishes the risk of revealing unsolicited findings and shortens the time needed for analysis, but also results in missing couples with different mutations in the same gene. In addition to the proposed pipeline, couples should be offered testing for carrier status of frequent disorders that can present themselves by large deletions, non-exonic mutations or compound heterozygous mutations (e.g. thalassemia, spinal muscular atrophy, cystic fibrosis). Even though sensitivity is reduced, offering exome sequencing prospectively will increase reproductive options for consanguineous couples. [ABSTRACT FROM AUTHOR]

Saudi Arabia has a population of 27.1 million. Prevalence of many autosomal recessive disorders is higher than in other known populations. This is attributable to the high rate of consanguineous marriages (56%), the tribal structure, and large family size. Founder mutations have been recognized in many autosomal recessive disorders, many of which are overrepresented within certain tribes. On the other hand, allelic heterogeneity is also observed among common and rare autosomal recessive conditions. With the adoption of more advanced molecular techniques in the country in recent years in conjunction with international collaboration, the mapping of various autosomal recessive disorders has increased dramatically. Different genetic concepts pertinent to this highly inbred population are discussed here. Addressing such genetic disorders at the national level will become a cornerstone of strategic health care initiatives in the 21st century. Current efforts are hampered by many socio-cultural and health care related factors. Education about genetic diseases, establishment of a 'national registry' and mutational database, and enhanced healthcare access are crucial for success of any preventative campaign. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Objective: We provide the proof of principle that exome sequencing of only two affected siblings born to first-cousin parents is capable of directly identifying a single candidate gene for an autosomal recessive disorder. This strategy, which we call EX-HOM (EXome HOMozygosity), combines in a single step the capacity of exome sequencing to identify all the coding variants present in a genome with the property of homozygosity mapping to limit the search for candidate genes to specific chromosomal regions. Methods: We sequenced the exomes of two siblings born to first-cousin parents affected with dysmyelinating leukodystrophy and spastic paraparesis caused by a mutation in FA2H. We used exome sequencing data to identify homozygous regions shared by the two affected siblings (EX-HOM regions), compared them with the regions of maximum LOD score obtained with SNP genotyping, and selected the candidate variants within. Results: We identified regions of shared homozygosity (>1 Mb) accounting for about 290 Mb, containing only 3 candidate variants. Among these, the FA2H mutation remained the only plausible one. Conclusion: In single consanguineous pedigrees with a few affected sibs, EX-HOM can be a one-step approach to identify the candidate genetic defect, bypassing obstacles such as genetic heterogeneity and the need for large pedigrees. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Congenital adrenal hyperplasia (CAH) owing to 21-hydroxylase deficiency is an autosomal recessive disorder caused by mutations in the CYP21A2 gene. Females affected with classical CAH are at risk for genital ambiguity, but can be treated in utero with dexamethasone before 9 gestational weeks to prevent virilization. Early genetic diagnosis is unavailable through current invasive methods of chorionic villus sampling and amniocentesis. New developments in prenatal genetic testing utilize fetal DNA extracted from maternal blood through noninvasive methods, which allow the determination of fetal gender and the diagnosis of CAH at an early gestational age (<9 weeks). Noninvasive prenatal diagnosis allows for the establishment of early and effective management plans in fetuses at risk for CAH and avoids unnecessary prenatal dexamethasone treatment [ABSTRACT FROM AUTHOR]

Blackburn with Darwen Primary Care Trust (PCT) provides services to a substantial Asian population in which the practice of consanguineous marriage is common and there is a high incidence of autosomal recessive disorders. The aim was to provide and evaluate a genetic service accessible to consanguineous families from the South Asian community who had a child affected by an autosomal recessive disorder. Information on genetic risk was provided along with the offer of genetic testing for members of the extended family to identify gene carriers and facilitate informed reproductive choices. An Urdu-speaking health visitor was employed to establish a community-based, hospital-linked genetic service in conjunction with local paediatric and regional genetic services offered to parents who had an affected child and 71 of their relatives. The service was evaluated using a specifically designed questionnaire. There was a high uptake of the service (95% of index parents and 92% of relatives to whom it was offered) and a high uptake of carrier testing (94% of relatives to whom it was offered). Eight requests for prenatal diagnosis were made during the course of the service development. Many individuals stated they would consider genetic risk when making future marriage and reproductive plans. Input from a health care worker from the same ethnic background who provided information in their own language was highly valued. Family orientated genetic services for ethnic groups practicing consanguinity can be acceptable and effective when provided in a culturally appropriate manner. [ABSTRACT FROM AUTHOR]

Introduction. Sickle cell disease (SCD) is a clinically significant hemoglobinopathy with increasing global incidence. We describe our experience of using pre-implantation genetic diagnosis (PGD) for the prevention of SCD at a tertiary referral centre in London. Methods. Between January 2002 and December 2007, of 78 at-risk couples referred for PGD treatment, 12 couples (15%) underwent 16 PGD cycles for the prevention of SCD. Results. The live birth rate was 13% per initiated cycle, 18% per embryo transfer and 17% per couple. Conclusions. Although PGD for prevention of the birth of a child affected by SCD is a viable treatment option for couples at risk of having an affected child, potential barriers to uptake of this service need to be fully addressed to ensure its availability to all couples seeking to avoid having a child affected with SCD. [ABSTRACT FROM AUTHOR]

Abstract: Ellis-van Creveld syndrome (chondroectodermal or mesoectodermal dysplasia) is an autosomal recessive disorder. Initial reports of the syndrome identified a tetrad of clinical manifestations, including chondrodysplasia, postaxial polydactyly, ectodermal dysplasia, and congenital heart disease (CHD). Additional involvement may occur in organs of endodermal origin, such as the pulmonary, renal, gastrointestinal (hepatic and pancreatic), hematologic, and central nervous systems. The perioperative care of a 2-year, 8-month-old girl who underwent surgical correction of CHD is presented. [Copyright &y& Elsevier]

The Arabs in general are genetically diverse. Major factors that contributed to their diversity include the migrations of Semitic tribes from the Arabian Peninsula, the Islamic expansion in the 7th century AD, the Crusade wars and the recent migration dynamics. These events have resulted in the admixture of the original Arabs with other populations extending from east and south Asia to Europe and Africa. Their demographic features include high rates of consanguinity, a large family size and a rapid population growth. There is a high frequency of autosomal recessive disorders and increased frequencies of homozygosity for autosomal dominant traits, such as familial hypercholesterolemia and X-linked traits, such as glucose-6-phosphate dehydrogenase deficiency. The patterns of autosomal recessive disorders, including their mutations, may be different in various geographic locations within the Arab world. However, there are disorders that are specifically prevalent among the Arabs either uniformly or in certain locations. The Arab Genetic diseases include Bardet-Biedl syndrome, Meckel syndrome, autosomal recessive severe childhood muscular dystrophy, osteopetrosis and renal tubular acidosis, Sanjad-Sakati syndrome and others. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Objectives: The local frequencies of genetic disorders in Oman apart from hemoglobinopathies are largely unknown. The aim of the present study was to evaluate birth prevalence of commonly diagnosed autosomal recessive diseases and to estimate needs and priorities of genetic services. Methods: Analysis of the years 1993–2002 using a hospital-based registry of genetic diseases was attempted. More than 3,000 records were reviewed. Only patients with definite diagnosis were included in the analysis. Genetically determined diseases occurring less frequently than 1 in 50,000 births are not included. Results: A number of rare autosomal recessive diseases are found to have a prevalence at least 1 in 50,000 livebirths. Conclusions: The data suggest that genetic diseases are important as major contributors to perinatal and childhood mortality and morbidity. The need for preventive genetic service is essential for the health of the community in Oman. Autosomal recessive diseases were frequently concentrated in specific geographical areas, which can be explained by founder effect and genetic drift. However, the hospital-based registry may present incomplete information. Further prospective studies are needed to provide more detailed data. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Counseling recurrence risks for monogenic disorders is one of the mainstays of human genetics. However, in practice, consultations concerning autosomal recessive disorders exceed the simple conveyance of a 25 % recurrence risk for future offspring. Medical geneticists should be aware of the multifaceted way in which autosomal recessive disorders can pose a diagnostic and counseling challenge in their daily lives and of the pitfalls they might encounter. Although the intentional or incidental detection of carrier states for autosomal recessive diseases happens more and more frequently, our current practice when clarifying their associated reproductive risks remains unsystematic and often subjectively guided. We question whether the approach of focusing on small recurrence risks for a single familial disease with extensive single-gene tests in the partner of a known carrier truly addresses the counseling needs of a couple seeking preconceptional genetic advice. Different perspectives between patients and medical practitioners (or between different medical practitioners) on "acceptable risks" or the extent to which such risks must be minimized raise the question of whether existing professional guidelines need to be clarified., Competing Interests: Conflict of interest: Authors state no conflict of interest., (© 2021 Netzer et al., published by De Gruyter.)

Nonclassic 21-hydroxylase deficiency is a frequent autosomal recessive disorder which causes decreased fertility and is easily treated. It occurs with the highest frequency of any other autosomal recessive disorder in humans. [Copyright &y& Elsevier]

Consanguineous marriage, marriage between close biological kin, especially that between first cousins, is socially favored in some parts of North Africa, the Middle East and Asia. An increased rate of congenital anomalies and autosomal recessive disorders are significantly associated with such practice. In such communities, misunderstanding and external attempts to discourage such marriage without proper genetic counseling seem to be inappropriate and unsuccessful. Update in knowledge of clinicians especially pediatricians is the aim of this paper regarding importance and issues behind consanguineous marriage.