Single Autosomal Recessive Gene Research Articles

THALASSEMIA AND NUTRITIONAL STATUS IN CHILDREN

Thalassemia is an autosomal recessive single gene disorder due to an imbalance in the production of globin chains, namely α-globin and β-globin chains, which until now the case is increasing with manifestations of severe anemia and can have an impact on nutritional status. Malnutrition is one of the effects of thalassemia due to rapid erythrocyte turnover. The purpose of this paper is to discuss and provide information regarding the definition, epidemiology, classification, pathogenesis, diagnosis, complications, management, and nutritional status to minimize growth disorders in thalassemia patients. This research is a literature study, which is a type of research that collects, manages, uses, and reviews research data sourced from scientific research journals, previous research manuscripts, and textbooks. The results of the literature review are a factor of good nutritional status in thalassemia patients can be affected by various factors, one of which is increased energy expenditure which can offset good intake and consumption patterns. One of the assessments of nutritional status in thalassemia patients is the Upper Arm Circumference (UAC) because it can be used in organomegaly patients. Many factors can affect the nutritional status of children, especially in children with thalassemia.

The utility of whole exome sequencing for identification of the molecular etiology in autosomal recessive developmental and epileptic encephalopathies.

Developmental and epileptic encephalopathies (DEEs) are a group of devastating disorders caused by epileptic activity, resulting in deterioration in developmental, cognitive, and motor functions. The number of genes identified as being responsible for DEEs has been increasing rapidly. However, despite a comprehensive molecular analysis, a molecular diagnosis can only be established in 50% of cases. The aim of this project is to use whole exome sequencing (WES) to determine the molecular etiology of DEEs in undiagnosed patients with a pedigree suggestive of an autosomal recessive single gene disease. Three DEE families, having either consanguineous parents of an affected individual and/or having more than one affected offspring, were enrolled in the project. Prior to this project, the families had been evaluated using a next-generation sequencing panel including 16 DEE genes in a previous study; however, no molecular diagnosis could be established. In five cases from the three selected DEEs families in our study, the genetic etiology was investigated using WES. All patients in the study group had infantile onset epileptic seizures; however, semiologies varied. All patients presented with severe developmental delay. WES revealed biallelic disease causing mutations in DENDD5A, GRN, and TBCD genes in family 1, family 2, and family 3, respectively. In each family, the identified variants associated with the disease were segregated. Reverse phenotyping supported the molecular analysis. This study provided a valuable contribution to the genotype-phenotype relationship by determining rare epilepsy syndromes in undiagnosed patients previously. WES is a useful diagnostic alternative, particularly in consanguineous families.

A prospective study on growth pattern and effect of serum ferritin, haemoglobin levels on physical growth inthalassemic childern

Background: Thalassemia major is one of the most common genetically transmitted diseases in the world and is associated with reduced synthesis of structurally normal hemoglobin. -thalassemia is an autosomal recessive single gene disorder. Keeping this in mind, present study was undertaken to study the growth pattern of transfusion dependent thalassaemic children and to assess the effect serum ferritin, haemoglobin levels on physical growth pattern in thalassemic children. Methods: A prospective observational study was done on 52 thalassaemic patients (aged 2 years-12 years) who attended Department of Pediatrics. Anthropometric measurements like weight and height were taken from all patients. Sexual maturity rating was done in girls 10 years and boys11 years. Lab parameters included pre-transfusion hemoglobin (Hb) and serum ferritin. Percentiles for weight, height and body mass index were calculated using WHO (2007) reference data. Results: Among 52 transfusion dependent thalassemic children majority i.e. 35(67.3%) were more than 6years.Mean age was 8 3.05. Majority of children i.e. 32(61.6%) were male. Mean age of diagnosis was 9.2 months, youngest case being diagnosed at 3rd month, and oldest being at 20 months. Among 52 children most of them are born to non-consanguineous couple. Majority of the children had pre-transfusion haemoglobin in the range of 5-7 gm%. Among 52 children 61.6 % (n=32) had mean serum ferritin more than 2500, and 38.4% (n=20) had mean serum ferritin value less than 2500. The present results showed that, Among 52 children according to IAP standards weight for age less than 50th percentile was 86.5% (n=45) and more than 50th percentile was 13.5%(n=7). Among 45(86.5%) children who had less than 50th percentile weight for age, 19.2 % (n=10) children were less than 6 years of age, remaining 67.3% (n=35) children belongs to 7 to 12 years of age. Among weight for age

Alpha Globin Gene Mutation: A Major Determinant of Hydroxyurea Response in Transfusion-Dependent HbE-β-Thalassaemia

Thalassaemias are the most common inherited autosomal recessive single gene disorders characterised by chronic hereditary haemolytic anaemia due to absence or reduced synthesis of one or more of the globin chains. Haemoglobin E (HbE)-β-thalassaemia is the genotype responsible for approximately one-half of all cases of severe β-thalassaemia worldwide. This study proposes to evaluate response of hydroxyurea in reducing transfusion requirements of severe HbE-β-thalassaemia patients, and its correlation with foetal haemoglobin (HbF) level and α-mutation. Hydroxyurea was started at a baseline dose in 82 transfusion-dependent HbE-β-thalassaemia patients. HbF levels and %F-cells were measured. β-Thalassaemia mutations and α-globin gene deletions and triplications were detected by amplification refractory mutation system (ARMS)-polymerase chain reaction (PCR) and Gap-PCR, respectively. Patients were categorised as good (41.5%), moderate (31.7%), and poor responders (26.8%) based on their decrease in transfusion requirements. Nine patients were excellent responders who became transfusion independent. The mean increase in HbF levels and %F-cells after therapy was correlated with decrease in transfusion requirements. Patients having a deletion of the α-globin gene were better responders. The response was proportional to the number of α-globin gene deletions. We conclude that hydroxyurea treatment decreases transfusion requirements, and the response correlates with α-globin gene deletions.

A study of growth pattern in regularly transfused thalassaemic children of age group of 2 years to 12 years

Background: ß-thalassemia is an autosomal recessive single gene disorder. Physical growth failure is one of the most important complications of thalassemia. Very few data regarding growth pattern of thalassemic children is available from India especially North East part. Keeping this in mind, present study was undertaken. To study the growth pattern of transfusion dependent thalassaemic children and to compare growth pattern between regularly and irregularly transfused children.Methods: A cross-sectional observational study was done on 38 thalassaemic patients (aged 2 years-12 years) who attended Department of Pediatrics, Assam Medical College Dibrugarh. History, physical examination and investigations were done and filled in predesigned proforma. Anthropometric measurements like weight and height were taken from all patients. Sexual maturity rating was done in girls ≥10 years and boys ≥11 years. Lab parameters included pre-transfusion hemoglobin (Hb), serum ferritin, LFT, RFT, Thyroid profile. Percentile for weight, height and body mass index were calculated using WHO (2007) reference data. Collected data were compared with age and sex matched normal children.Results: About 34.21% transfusion dependent children had under-nutrition and 50% had stunting. 42% had thinness. Stunting was more in irregularly transfused children (81.25%) as compared to regularly transfused children which was highly significant (p<0.001). Under-nutrition among irregularly transfused children was more (40%) compared to regularly transfused children (28.57%). Pubertal spurt was delayed in 66% children. Those who had Hb <5 gm/dl had 100% stunting and under-nutrition.Conclusions: Regular blood transfusion with growth monitoring and appropriate iron chelation (Sr. Ferritin >1000 ng/ml) is of utmost importance in transfusion dependent thalassaemic children.

Knowledge, Attitude and Practices of Parents of Thalassemic Children in District Patiala, Punjab, India

Introduction: β-thalassemia is an autosomal recessive single gene disorder characterized by defective production of hemoglobin and excessive destruction of Red Blood Cells. The defect causes an abnormal development of Red Blood Cells and ultimately anemia. The cultural and religious scenario in Muslims, Khatris and Punjabis migrated from Pakistan is such that consanguineous marriages are quite common. There is no concept of premarital screening of counseling of individuals with a family history of disease. The only way to prevent the disease and to reduce the morbidity and mortality is by educating the general population. For this reason, present study was taken to evaluate the knowledge, attitude and practices of parents of Thalassemic children. Objectives: To assess the Knowledge, Attitude and Practices of Parents of Thalassemic Children. Methods: The study was conducted on parents of 100 patients of thalassemia who are coming regularly for blood transfusion in Thalassemia Day Care Centre (TDCC) run by Patiala Thalassemic Children Welfare Association (PTCWA) at Rajindra Hospital, Patiala to collect the relevant data for the study to evaluate the Knowledge, Attitude and Practices (KAP) of parents of thalassemic children. Results: Mean age of the patients was 8.36 years. 66% patients were males and 34% were females. 41% of the patients were from Khatri community and 59% were from other communities. Family history of thalassemia was present in 23% of the cases and history of consanguineous marriage was present in 4% of the cases. Seventy six percent of the parents knew about the prenatal diagnosis that could be performed to prevent the birth of thalassemic children. Knowledge regarding the treatment options available was found more in parents from Bania, Khatri and Kamboj communities. More positive attitude of parents towards prevention of thalassemia was found in parents who have answered 11-15 questions from Knowledge questionnaire. Conclusion: There should be a community based educational efforts to increase awareness of this problem especially to the people from low socioeconomic class and from rural area. Control of thalassemia requires treatment of the individual patients as well as a community based educational effort to increase the awareness of this problem.

Genetic determinants related to pharmacological induction of foetal haemoglobin in transfusion-dependent HbE-β thalassaemia.

Thalassaemia are the most common inherited autosomal recessive single gene disorders characterized by chronic hereditary haemolytic anaemia due to the absence or reduced synthesis of one or more of the globin chains. Haemoglobin E-β thalassaemia is the genotype responsible for approximately one half of all severe beta-thalassaemia worldwide. This study proposes to evaluate the effect of various molecular parameters on the response of hydroxyurea. Hydroxyurea was started at an initial dose of 10mg/kg of body weight/day on 110 transfusion-dependent HbE-β thalassaemia patients. HbF level was measured by HPLC analysis. β-Thalassaemia mutations, XmnI and five other SNPs, and α-globin gene deletions and triplications were detected by ARMS-PCR, RFLP-PCR and Gap-PCR, respectively. Based on the factors for evaluating hydroxyurea-response, 42 patients were responders as they showed an increment of Hb from a mean baseline value of 6.45g/dl (± 0.70) to 7.78g/dl (± 0.72) post-therapy. Based on increase in HbF above the median value (14.72%) post-therapy, 78 patients were found to be responders. All the 78 responders showed mean decrease in transfusion of 74.26% (± 8.32) with a maximum decrease of 98.43%. There was a significant correlation between decrease in transfusion and increase in HbF level for all 78 responders. XmnI polymorphism showed the strongest association (p < 0.0001) with increase in HbF levels and Hb levels. Patients with α-globin gene deletions were better responders. It was concluded that hydroxyurea treatment is effective in transfusion-dependent HbE-β thalassaemia patients and the response is best in patients having both XmnI polymorphism and α-deletion.

Genetic assessment and folate receptor autoantibodies in infantile-onset cerebral folate deficiency (CFD) syndrome

IntroductionCerebral folate deficiency (CFD) syndromes are defined as neuro-psychiatric conditions with low CSF folate and attributed to different causes such as autoantibodies against the folate receptor-alpha (FR) protein that can block folate transport across the choroid plexus, FOLR1 gene mutations or mitochondrial disorders. High-dose folinic acid treatment restores many neurologic deficits. Study aims and methodsAmong 36 patients from 33 families the infantile-onset CFD syndrome was diagnosed based on typical clinical features and low CSF folate. All parents were healthy. Three families had 2 affected siblings, while parents from 4 families were first cousins.We analysed serum FR autoantibodies and the FOLR1 and FOLR2 genes. Among three consanguineous families homozygosity mapping attempted to identify a monogenetic cause. Whole exome sequencing (WES) was performed in the fourth consanguineous family, where two siblings also suffered from polyneuropathy as an atypical finding. ResultsBoys (72%) outnumbered girls (28%). Most patients (89%) had serum FR autoantibodies fluctuating over 5–6 weeks. Two children had a genetic FOLR1 variant without pathological significance. Homozygosity mapping failed to detect a single autosomal recessive gene. WES revealed an autosomal recessive polynucleotide kinase 3´phosphatase (PNKP) gene abnormality in the siblings with polyneuropathy. DiscussionInfantile-onset CFD was characterized by serum FR autoantibodies as its predominant pathology whereas pathogenic FOLR1 gene mutations were absent. Homozygosity mapping excluded autosomal recessive inheritance of any single responsible gene. WES in one consanguineous family identified a PNKP gene abnormality that explained the polyneuropathy and also its contribution to the infantile CFD syndrome because the PNKP gene plays a dual role in both neurodevelopment and immune-regulatory function. Further research for candidate genes predisposing to FRα-autoimmunity is suggested to include X-chromosomal and non-coding DNA regions.

Biomarkers of vitamin B 12 status respond to therapy in Gaucher disease

Cerebral folate deficiency (CFD) syndromes are defined as neuro-psychiatric conditions with low CSF folate and attributed to different causes such as autoantibodies against the folate receptor-alpha (FR) protein that can block folate transport across the choroid plexus, FOLR1 gene mutations or mitochondrial disorders. High-dose folinic acid treatment restores many neurologic deficits.Among 36 patients from 33 families the infantile-onset CFD syndrome was diagnosed based on typical clinical features and low CSF folate. All parents were healthy. Three families had 2 affected siblings, while parents from 4 families were first cousins.We analysed serum FR autoantibodies and the FOLR1 and FOLR2 genes. Among three consanguineous families homozygosity mapping attempted to identify a monogenetic cause. Whole exome sequencing (WES) was performed in the fourth consanguineous family, where two siblings also suffered from polyneuropathy as an atypical finding.Boys (72%) outnumbered girls (28%). Most patients (89%) had serum FR autoantibodies fluctuating over 5–6 weeks. Two children had a genetic FOLR1 variant without pathological significance. Homozygosity mapping failed to detect a single autosomal recessive gene. WES revealed an autosomal recessive polynucleotide kinase 3´phosphatase (PNKP) gene abnormality in the siblings with polyneuropathy.Infantile-onset CFD was characterized by serum FR autoantibodies as its predominant pathology whereas pathogenic FOLR1 gene mutations were absent. Homozygosity mapping excluded autosomal recessive inheritance of any single responsible gene. WES in one consanguineous family identified a PNKP gene abnormality that explained the polyneuropathy and also its contribution to the infantile CFD syndrome because the PNKP gene plays a dual role in both neurodevelopment and immune-regulatory function. Further research for candidate genes predisposing to FRα-autoimmunity is suggested to include X-chromosomal and non-coding DNA regions.

Clinical and neurophysiological assessments of an infant with acute neurovisceral acid sphingomyelinase deficiency

Cerebral folate deficiency (CFD) syndromes are defined as neuro-psychiatric conditions with low CSF folate and attributed to different causes such as autoantibodies against the folate receptor-alpha (FR) protein that can block folate transport across the choroid plexus, FOLR1 gene mutations or mitochondrial disorders. High-dose folinic acid treatment restores many neurologic deficits.Among 36 patients from 33 families the infantile-onset CFD syndrome was diagnosed based on typical clinical features and low CSF folate. All parents were healthy. Three families had 2 affected siblings, while parents from 4 families were first cousins.We analysed serum FR autoantibodies and the FOLR1 and FOLR2 genes. Among three consanguineous families homozygosity mapping attempted to identify a monogenetic cause. Whole exome sequencing (WES) was performed in the fourth consanguineous family, where two siblings also suffered from polyneuropathy as an atypical finding.Boys (72%) outnumbered girls (28%). Most patients (89%) had serum FR autoantibodies fluctuating over 5–6 weeks. Two children had a genetic FOLR1 variant without pathological significance. Homozygosity mapping failed to detect a single autosomal recessive gene. WES revealed an autosomal recessive polynucleotide kinase 3´phosphatase (PNKP) gene abnormality in the siblings with polyneuropathy.Infantile-onset CFD was characterized by serum FR autoantibodies as its predominant pathology whereas pathogenic FOLR1 gene mutations were absent. Homozygosity mapping excluded autosomal recessive inheritance of any single responsible gene. WES in one consanguineous family identified a PNKP gene abnormality that explained the polyneuropathy and also its contribution to the infantile CFD syndrome because the PNKP gene plays a dual role in both neurodevelopment and immune-regulatory function. Further research for candidate genes predisposing to FRα-autoimmunity is suggested to include X-chromosomal and non-coding DNA regions.

Infusion-related reactions in patients with mucopolysaccharidosis type II on idursulfase enrolled in the Hunter Outcome Survey (HOS)

Cerebral folate deficiency (CFD) syndromes are defined as neuro-psychiatric conditions with low CSF folate and attributed to different causes such as autoantibodies against the folate receptor-alpha (FR) protein that can block folate transport across the choroid plexus, FOLR1 gene mutations or mitochondrial disorders. High-dose folinic acid treatment restores many neurologic deficits.Among 36 patients from 33 families the infantile-onset CFD syndrome was diagnosed based on typical clinical features and low CSF folate. All parents were healthy. Three families had 2 affected siblings, while parents from 4 families were first cousins.We analysed serum FR autoantibodies and the FOLR1 and FOLR2 genes. Among three consanguineous families homozygosity mapping attempted to identify a monogenetic cause. Whole exome sequencing (WES) was performed in the fourth consanguineous family, where two siblings also suffered from polyneuropathy as an atypical finding.Boys (72%) outnumbered girls (28%). Most patients (89%) had serum FR autoantibodies fluctuating over 5–6 weeks. Two children had a genetic FOLR1 variant without pathological significance. Homozygosity mapping failed to detect a single autosomal recessive gene. WES revealed an autosomal recessive polynucleotide kinase 3´phosphatase (PNKP) gene abnormality in the siblings with polyneuropathy.Infantile-onset CFD was characterized by serum FR autoantibodies as its predominant pathology whereas pathogenic FOLR1 gene mutations were absent. Homozygosity mapping excluded autosomal recessive inheritance of any single responsible gene. WES in one consanguineous family identified a PNKP gene abnormality that explained the polyneuropathy and also its contribution to the infantile CFD syndrome because the PNKP gene plays a dual role in both neurodevelopment and immune-regulatory function. Further research for candidate genes predisposing to FRα-autoimmunity is suggested to include X-chromosomal and non-coding DNA regions.

A Simple Network to Remove Interference in Surface EMG Signal from Single Gene Affected Phenylketonuria Patients for Proper Diagnosis

Recently Autosomal Recessive Single Gene (ARSG) diseases are highly effective to the children within the age of 5–10 years. One of the most ARSG disease is a Phenylketonuria (PKU). This single gene disease is associated with mutations in the gene that encodes the enzyme phenylalanine hydroxylase (PAH, Gene 612349). Through this mutation process, PAH of the gene affected patient can not properly manufacture PAH as a result the patients suffer from decreased muscle tone which shows abnormality in EMG signal. Here the extraction of the quality of the PKU affected EMG (PKU-EMG) signal is a keen interest, so it is highly necessary to remove the added ECG signal as well as the biological and instrumental noises. In the Present paper we proposed a method for detection and classification of the PKU affected EMG signal. Here Discrete Wavelet Transformation is implemented for extraction of the features of the PKU affected EMG signal. Adaptive Neuro-Fuzzy Inference System (ANFIS) network is used for the classification of the signal. Modified Particle Swarm Optimization (MPSO) and Modified Genetic Algorithm (MGA) are used to train the ANFIS network. Simulation result shows that the proposed method gives better performance as compared to existing approaches. Also it gives better accuracy of 98.02% for the detection of PKU-EMG signal. The advantages of the proposed model is to use MGA and MPSO to train the parameters of ANFIS network for classification of ECG and EMG signal of PKU affected patients. The proposed method obtained the high SNR (18.13 ± 0.36 dB), SNR (0.52 ± 1.62 dB), RE (0.02 ± 0.32), MSE (0.64 ± 2.01), CC (0.99 ± 0.02), RMSE (0.75 ± 0.35) and MFRE (0.01 ± 0.02), RMSE (0.75 ± 0.35) and MFRE (0.01 ± 0.02). From authors knowledge, this is the first time a composite method is used for diagnosis of PKU affected patients. The accuracy (98.02%), sensitivity (100%) and specificity (98.59%) helps for proper clinical treatment. It can help for readers/researchers to improve the aforesaid performance for future prospective.

A descriptive analysis of 14 cases of progressive-psuedorheumatoid-arthropathy of childhood from south India: Review of literature in comparison with Juvenile Idiopathic Arthritis

Progressive-psuedorheumatoid-arthropathy of childhood (PPAC) is an autosomal recessive single gene skeletal dysplasia involving joints. The gene attributed to its cause is WNT1-inducible-signaling pathway protein3 (WISP3). To study the clinical and radiographic presentation of PPAC in Indian patients and to compare with described features of PPAC and Juvenile Idiopathic Arthritis (JIA) from published literature. All cases (n = 14) of PPAC seen in the Rheumatology and Clinical Genetics outpatient clinic between 2008 and 2011 with classical, clinical, and radiological features were studied. The demographic and clinical data were obtained from medical records of the outpatient visits. Slight female preponderance (57%) and history of consanguinity in parents (43%) was observed in this group. The median age at onset was 4.5 years (range from birth to 9 years of age). Early presentation below the age of 3 years was seen in 3/14 patients (21%) in this group. The growth of all the patients fell below the 3rd percentile for the age. Historically, hip joint involvement was the most common presenting feature; however, elbow, wrist, knees, feet, spine, shoulder joints and small joints, namely proximal interphalangeal (PIP), distal interphalangeal (DIP), metacarpophalangeal (MCP), metatarsophalangeal joints (MTP), and interphalangeal joints (IP) of the feet, were also involved, either clinically or radiologically in varying proportions. Platyspondyly was noted in all. Molecular analysis of the WISP3 gene identified mutations in all the 5 individuals in whom it was done. This descriptive case series of PPAC from India reports distinctly differentiating clinical, radiological, and molecular markers in contrast with classically described features of JIA, its mimic. Early presentation (age of onset below 3 years) with involvement of interphalangeal joints seen in three patients (21%) was a unique finding, with missense WISP3 gene mutations in all of them. Timely diagnosis of this entity can spare the patient from unnecessary investigations and toxic medications.

Inheritance and Developmental Pattern of Cerebral Hernia in the Crested Polish Chicken

A number of crested chicken strains, such as the Polish chicken, exhibit a bony protuberance in the anterodorsal region of their skulls. The shape of their brain shows the anatomical peculiarity that is characterized by the upthrusting of cerebral hemispheres, called "cerebral hernia." Some early works suggested that this phenotype may be caused by a genetic factor and any modifiers influencing the development of brain and/or skull. However, the causative gene and its formation mechanism are still unclear. The present study is aimed to analyze the inheritance and ontogenic process of cerebral hernia in the crested Polish chicken. Firstly, we constructed the resource family with the Polish chicken and PNP inbred strain. Genetic analysis of this family revealed that cerebral hernia is controlled by a single autosomal recessive gene and is closely associated with crest formation. Furthermore, our morphological analysis of brain structures in the progenies suggested that the significant enlargement of brain cavity at later stages of embryos, particularly after 15 days of incubation, may be the main cause of cerebral hernia.

Primary appendiceal mucinous adenocarcinoma alongside with situs inversus totalis: a unique clinical case

IntroductionMucinous adenocarcinoma is a rare neoplasm of the gastrointestinal tract and one of the three major histological subtypes of the primary appendiceal adenocarcinoma. The most common type of presentation is that of acute appendicitis and the diagnosis is usually occurred after appendectomy. The accurate preoperative diagnosis and management of the above condition represents a real challenge when uncommon anatomic anomalies such intestinal malrotation and situs inversus take place. Situs inversus totalis with an incidence of 0.01% is an uncommon condition caused by a single autosomal recessive gene of incomplete penetration in which the major visceral organs are mirrored from their normal positions.Case presentationWe present an unusual case of a 59 years old, previously healthy man presented with a left lower quadrant abdominal pain, accompanied with low fever, leukocytosis, anorexia and constipation. A chest radiograph demonstrated dextrocardia with a right side positioned stomach bubble. Both preoperative US and CT scan of the abdomen and pelvis declared situs inversus, with a characteristic thickening in its wall, appendix situated in the left lower quadrant of the abdomen. These findings reached to the diagnosis of acute appendicitis with situs inversus and a standard appendicectomy was performed. Pathologic evaluation established primary mucinous adenocarcinoma of the appendix and three months afterwards the patient underwent a subsequent extended left hemicolectomy.ConclusionIn conclusion, the occurrence of primary appendiceal mucinous adenocarcinoma along with situs inversus, definitely accounts as a unique clinical case. Even synchronous manifestation of primary mucinous adenocarcinoma of the appendix and situs inversus totalis represents an unusual anatomo-pathological entity, all physicians should be familiar having the knowledge to make an appropriate and accurate diagnosis that will lead to prompt and correct treatment.

Syndactyly lethal: New mutation with multiple malformations occurring in Sprague Dawley rats

We previously found newborns exhibiting syndactyly of both fore- and hindlimbs in a litter from a pair of Sprague Dawley rats. Continuous breeding of the parental animals yielded pups with the same anomaly in following litters, suggesting that the syndactyly was genetic in origin. In the present study, as all the syndactylous pups died on postnatal day 0, we conducted genetic analyses using 30 phenotypically normal female progeny and the sire. The females were subjected to caesarean section on day 20 of gestation and the fetuses were examined for the phenotypes. The results of the mating experiments suggest that the mutant phenotype is caused by a single autosomal recessive gene at a homozygous condition. As homozygous mutants are lethal at the neonatal stage, the mutant gene was named syndactyly lethal, gene symbol syl. The mutant rats have multiple abnormalities, such as syndactyly, micrognathia, fused/absent/small lung lobes, absent kidney and ureter, small spleen, small uterus, fused phalanges, sternoschisis, absent/detached rib, and splitting/fused/absent/small thoracic vertebra, some of which must be the cause of death on postnatal day 0. This mutant is considered to be useful for investigating the mechanisms and/or pathogenesis of syndactyly, as well as the accompanying malformations.

Inheritance of a new albino mutation in Brazilian free-range black chickens

A genetically recessive albino mutation, which inhibits pigment development in the eyes, skin, and feathers of domestic chickens from Brazil, is described. This mutation appeared in a flock of completely black chickens of a private breeder. There are no information on the origin, breed, or specific line of the birds. Pigment inhibition is apparently complete in the feathers and eyes. Bird sight is very impaired, but no histological examination was carried out. Ratios obtained in F2 and backcrossed birds indicate that a single autosomal recessive gene is responsible for the condition. The data suggest that the absence of melanin in the eyes, skin, and feathers (symbol cc) is a mutation of the pigmented C wild gene.

Mutation of Dock5, a member of the guanine exchange factor Dock180 superfamily, in the rupture of lens cataract mouse

Rupture of lens cataract (RLC) in the mouse is a spontaneous mutation inherited by a single autosomal recessive gene mapped on chromosome 14. Fine mapping of the mutant locus revealed a nucleotide deletion of 27-bp at the end of 15th exon of Dock5 (Dedicator of cytokinesis-5), a member of the Dock gene superfamily. Since the deletion occurred in-frame, the RLC-DOCK5 protein had a deletion of 9 amino acids (a.a. 506–514) in the DHR1 (DOCK homology region-1) domain that is essential for DOCK5, a GTP-exchanger for Rac1. Although Dock5 mRNA was intensely expressed equally in mutant and wild-type lenses, DOCK5 protein was hardly detectable in the mutant lens. In contrast, expression of Dock180, another member of Dock subfamily A, was not affected in RLC. Immunohistochemically, DOCK5 was stained intensely in the cytoplasm of the anterior epithelial cells and weakly in lens fiber of the wild type lenses, but little in RLC lens. These observations suggest that the mutation may somehow destabilize DOCK5 protein. We propose to designate the mutant allele of rlc as Dock5rlc. Relevance of the signaling pathway involving DOCK5-RAC1 in maintenance of lens integrity of growing lens is discussed.

International Perspectives

Consanguinity is defined as the marriage between individuals who have a common ancestor. Many epidemiologic studies have examined consanguineous marriages and their health impact on offspring. Because related individuals share genes from a common ancestor, homozygosity is favored, and their progeny are more likely to have genetic disorders. Primarily, offspring of consanguineous parents are at a twofold greater risk than offspring of nonrelated parents for autosomal recessive disorders. (1)(2) Advances in genetics have led to a deeper understanding of the impact of inbreeding on the occurrence of genetic anomalies. Studies show that inbreeding is associated with mortality and morbidity in the fetal, neonatal, and childhood stages. Because consanguinity represents a risk factor for the occurrence of many deleterious outcomes, it is of major scientific and public health interest. This article summarizes the primary health-related adverse effects of consanguinity and discusses potential preventive measures. Despite the adverse effects caused by consanguineous unions, such relationships still occur in many countries. Bittles (3) has illustrated the global prevalence of consanguineous marriage (Fig. 1). The prevalence can be divided into three major regions. The first region includes Western Europe, North America, Australasia, and Russia, where only 1% of marriages are consanguineous. The second region includes the Iberian Peninsula, Japan, and South America, where 1% to 10% of marriages are consanguineous. The third region includes most of North and sub-Saharan Africa as well as West, Central and South Asia, where 20% to 50% of marriages are consanguineous. The specific types and rate of consanguineous marriages vary between and within countries. In the Middle East, the overall rate of consanguineous unions varies between 21% in Lebanon (Ministry of Public Health, 1998) and up to 58% in Saudi Arabia. (4) The most common form of consanguineous unions practiced is between first cousins. The rate of …

A Novel Hypothyroid Dwarfism Due to the Missense Mutation Arg479Cys of the Thyroid Peroxidase Gene in the Mouse

Recently, we found a novel dwarf mutation in an ICR closed colony. This mutation was governed by a single autosomal recessive gene. In novel dwarf mice, plasma levels of the thyroid hormones, T3 and T4, were reduced; however, TSH was elevated. Their thyroid glands showed a diffuse goiter exhibiting colloid deficiency and abnormal follicle epithelium. The dwarfism was improved by adding thyroid hormone in the diet. Gene mapping revealed that the dwarf mutation was closely linked to the thyroid peroxidase (Tpo) gene on chromosome 12. Sequencing of the Tpo gene of the dwarf mice demonstrated a C to T substitution at position 1508 causing an amino acid change from arginine (Arg) to cysteine (Cys) at codon 479 (Arg479Cys). Western blotting revealed that TPO protein of the dwarf mice was detected in a microsomal fraction of thyroid tissue, but peroxidase activity was not detected. These findings suggested that the dwarf mutation caused a primary congenital hypothyroidism by TPO deficiency, resulting in a defect of thyroid hormone synthesis.