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Biomedical subjects

I C Verma

Publications and source records attributed to I C Verma.

At least 19 recordsLinked to original sources

Leber's hereditary optic neuropathy with molecular characterization in two Indian families.

PURPOSE: Leber's hereditary optic neuropathy (LHON) presents in early adulthood with painless progressive blindness of one or both eyes. Usually there is a positive family history of similar disease on the maternal side. Definitive diagnosis can be established by finding the change in the mitochondrial gene. No molecular studies have been reported from India. MATERIAL AND METHODS: Clinical, ophthalmologic and molecular studies were carried out in two patients from different families and available first degree relatives. The subjects were tested for the three common mutations seen in LHON by molecular techniques of polymerase chain reaction using mutation specific primers. RESULTS: The mutations G3460A and G11778A in the mitochondrial genes MTND1 and MTND4, known to be causative for LHON, were found in one family each. CONCLUSION: Diagnosis of LHON should be considered in familial cases and in young adults with optic atrophy. Confirmation of diagnosis should be sought by molecular gene analysis. Genetic counselling should be offered to all 'at risk' relatives of a patient harbouring the mutation.

Adolescent↗

Prenatal diagnosis of phenylketonuria.

We report prenatal diagnosis of phenylketonuria by linkage analysis of the markers linked to the phenylalanine hydroxylase (PAH) gene. Three markers comprising STR (TCTAT)n in intron 3, VNTR (30bp long cassette) in the 3' UTR and Xmn1 RFLP were ascertained in the affected child, the parents and the chorionic villi sample. The foetus was confirmed to be heterozygous for the mutant allele. The diagnosis that the foetus was unaffected was confirmed by biochemical tests in the newborn.

Electrophoresis, Agar Gel↗

Dysmorphology diagnosis.

A patient with multiple malformations poses a diagnostic dilemma to the pediatrician. There are thousands of malformation syndromes described and diagnosis of a syndrome appears a daunting task. An approach to diagnosis of a malformation syndrome is presented. Relevant details in the history and examination, important investigations, the process of differential diagnosis, and search engines used to aid in diagnosis of a malformation syndrome are described.

Child↗

Genetic counseling and prenatal diagnosis in India--experience at Sir Ganga Ram Hospital.

UNLABELLED: The experiences in genetic counseling and prenatal diagnosis at a tertiary genetic center in India are described. Of 3500 subjects provided genetic counseling 28.7% were for prenatal diagnosis, 13.7% for mental retardation +/- malformations, 11.5% for thalassemia, hemophilia and leukemia, 8.5% for neural tube defects and other malformations, and 8% for muscle dystrophy and spinal muscle atrophy. Chromosomal studies in blood (n = 5459) were for recurrent abortions (57.8%), delayed milestones (14.7%), malformations (11%), and infertility and amenorrhea (10.2%). Indications for amniotic fluid studies (n = 835) were advanced maternal age (35.7%), high risk result on triple test (21.3%), previous child with trisomy 21 (21.3%) and abnormalities seen on ultrasound (11.1%). Molecular studies were mostly for thalassemia (843, 24.3%), Duchenne muscular dystrophy (443, 12.5%), fragile X syndrome (367, 10.3%), spinal muscular atrophy (315, 8.9%), thrombophilia profile (233, 6.6%), triplet repeat disorders-spinocerebellar ataxias, Huntington disease and Friedreich ataxia-162 (4.6%), cystic fibrosis 140 (3.9%) and mitochondrial disorders 101 (2.9%). Other disorders for which molecular diagnosis was done were intrauterine infections by PCR on the amniotic fluid, Prader Willi/Angelman syndromes, hemophilia, achondroplasia, congenital adrenal hyperplasia, and Apert syndrome etc. In biochemical studies triple marker tests were the most common (3239), followed by aminoacid chromatography (774). Among neurolipidosis metachromatic leukodystrophy was the commonest, followed by Krabbe's disease, Tay Sach disease and Gaucher disease. Of the mucopolysacharidoses Hurler syndrome was the commonest, followed by Hunter syndrome. These data are compared with previous studies and a change towards increased prenatal diagnostic tests is observed. The commonest indication for amniocentesis has changed to advanced maternal age. CONCLUSION: Advanced molecular, cytogenetic and biochemical techniques have been a useful addition for genetic counseling and prenatal diagnosis in India.

Chromosome Aberrations↗

Triple A syndrome--diagnostic and management issues.

The authors present a family with three children affected with triple A syndrome--one had died, one was saved by diagnosis and timely therapy, and one was born after the diagnosis in the second child. The gene for the syndrome has been cloned and genetic counseling should be offered to these families.

Adrenal Cortex Function Tests↗

Genetic counseling in acrocallosal syndrome.

This article reports two families with children having acrocallosal syndrome, an autosomal recessive disorder characterized by agenesis of corpus callosum, facial dysmorphism and polydactyly along with psychomotor retardation. Both families sought genetic counseling in subsequent pregnancies. Although the gene for the disorder is not yet identified, prenatal diagnosis was attempted by ultrasound studies. In both families, an affected fetus was diagnosed in the presence of postaxial polydactyly of hands and absence of corpus callosum. It is emphasized that pediatricians should make precise diagnosis in cases of dysmorphism and mental retardation, as this enable prenatal diagnosis in future pregnancies.

Abnormalities, Multiple↗

Molecular analysis of Huntington's disease and linked polymorphisms in the Indian population.

OBJECTIVES: To understand the population variation and haplotypes of Huntington's disease (HD) in India we have analysed CAG repeats at the HD locus together with closely linked polymorphisms in both HD patients and normal controls. MATERIALS AND METHODS: The CAG repeat and linked polymorphisms were analysed in 30 Indian HD families together with 250 ethnically matched controls using fluorescent polymerase chain reaction (PCR) based size estimation. RESULTS: CAG repeats at the HD locus in the normal population showed a mean size of 17.99 +/- 2.66 repeats (range nine to 33 repeats). The HD mutation in our families did not show any significant association with either the (CCG)7 or (CCG)10 allele while haplotype analysis suggested the over-representation of the 7-2-I (CCG-D4s127-Delta 2642 loci) haplotype in a subset of families. CONCLUSION: The distribution of CAG repeats in the normal population suggests a higher prevalence of HD, closer to that seen in Western Europe. Haplotype analysis suggests the presence of a founder mutation in a subset of families and provides evidence for multiple and geographically distinct origins for the HD mutation in India.

Female↗

Study of the single nucleotide polymorphism (SNP) at the palindromic sequence of hypersensitive site (HS)4 of the human beta-globin locus control region (LCR) in Indian population.

LCR, a genetic regulatory element, was examined in beta-thalassemia patients who do not show any mutation in the beta-globin genes. We sequenced LCR-HS2, HS3, and HS4 in samples from 16 such patients from the Indian population and found only one SNP A-G in the inverted repeat in HS4. A significant association was observed between the G allele and occurrence of beta-thalassemia by Fisher's exact test. The AG and GG genotypes showed higher relative risk as compared to the AA genotype. We also observed linkage disequilibrium between the A/G polymorphism and the AT-rich motif of the LCR HS2 region, suggesting that the G allele could be an evolutionarily new mutation in the study population.

Globins↗

The burden of genetic disorders in India and a framework for community control.

With a very large population and high birth rate, and consanguineous marriage favoured in many communities, there is a high prevalence of genetic disorders in India. An estimated 495,000 infants with congenital malformations, 390,000 with G6PD deficiency, 21,400 with Down syndrome, 9,000 with beta-thalassaemia, 5,200 with sickle cell disease, and 9,760 with amino acid disorders are born each year. The prevalence of late-onset multi-factorial disorders (including coronary artery disease, hypertension and psychiatric disorders) is also large. Due to inadequate diagnostic, management and rehabilitation facilities, the burden of these disorders is greater than in Western countries. Although genetic diseases receive little attention from the health services, research funding by the government has been liberal. Community control of common disorders like thalassaemia, Down syndrome, neural tube defects, and muscular dystrophies deserves high priority, and genetic services should be integrated into the existing primary health care and medical services. Most genetic counselling would have to be provided through training physicians who staff the district and medical school hospitals. To ensure future progress, there is a need to establish additional departments of medical genetics in medical schools.

Journal Article↗

Congenital myotonic dystrophy.

Myotonic muscular dystrophy is the most frequent autosomal muscular dystrophy affecting adults and children. It affects multiple organ systems and is probably the best example of variable expressivity in a human disease. This article presents a patient with congenital myotonic dystrophy who had facial dysmorphism, hypotonia, talipes, feeding and respiratory difficulties in the neonatal period and later presented to us with developmental delay and had percussion myotonia. His mother had clinical and electrophysiological features of myotonia. Expansion of unstable CTG trinucleotide repeat in the myotonic protein kinase gene was demonstrated in both. The identification of this molecular defect allows its specific diagnosis in relation to other neuromuscular disorders as well as accurate prenatal diagnosis.

Child, Preschool↗

Molecular characterization of mutations in Indian children with congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency.

Congenital adrenal hyperplasia (CAH) is the commonest cause of female pseudohermaphroditism. It is most often due to steroid 21-hydroxylase deficiency resulting from mutations in the CYP21 gene. This study was conducted to characterize mutations in the CYP21 gene, determine their frequency and correlate genotype with phenotype in Indian children with CAH. Twenty-eight patients with salt-wasting (SW) or simple-virilizing (SV) forms of the disease as well as parents and siblings were studied. Allele specific PCR was carried out and rapid characterization of six mutations was achieved in 23 patients. Twelve patients were homozygous for the mutations and 11 were heterozygous, of whom eight were compound heterozygotes and three were hemizygotes; no mutation was found in five patients. The homozygosity of the mutations was found to be high in our population. The most common mutation was Ile173Asn (31.8%), followed by intron2 splice (27.2%), Gln319stop (22.7%), gene deletion (15.9%) and Pro31Leu (2.2%). Genotype-phenotype correlations showed that the most frequent mutations in the SW group were intron2 splice and Gln319stop mutations (33.3% each) and Ile173Asn (71.4%) in the SV group.

Adrenal Hyperplasia, Congenital↗

SCA12 is a rare locus for autosomal dominant cerebellar ataxia: a study of an Indian family.

Spinocerebellar ataxia 12 (SCA12) is an autosomal dominant cerebellar ataxia (ADCA) described in a single family with a CAG repeat expansion in the PPP2R2B gene. We screened 247 index cases, including 145 families with ADCA, for this expansion. An expanded repeat ranging from 55 to 61 triplets was detected in 6 affected and 3 unaffected individuals at risk in a single family from India. The association of the PPP2R2B CAG repeat expansion with disease in this new family provides additional evidence that the mutation is causative.

Adult↗

Burden of genetic disorders in India.

India, like other developing countries, is facing an accelerating demographic switch to non-communicable diseases. In the cities congenital malformations and genetic disorders are important causes of morbidity and mortality. Due to the high birth rate in India a very large number of infants with genetic disorders are born every year almost half a million with malformations and 21,000 with Down syndrome. In a multi-centric study on the causes of referral for genetic counselling the top four disorders were repeated abortions (12.4%), identifiable syndromes (12.1%), chromosomal disorders (11.3%) and mental retardation (11%). In a more recent study in a private hospital the top reasons for referral were reproductive genetics (38.9%)--comprising prenatal diagnosis, recurrent abortions, infertility and Torch infections--mental retardation +/- multiple congenital anomalies (16.1%), Down syndrome (9.1%), thalassemia/haemophilia (8.8%), and muscle dystrophy/spinal muscular atrophy (8.4%). The disorders for which prenatal has been done over an 18-month-period are given. A recent study carried out in three centers (Mumbai, Delhi and Baroda) on 94,610 newborns by using a uniform proforma showed a malformation frequency of 2.03%, the commonest malformations are neural tube defects and musculo-skeletal disorders. The frequency of Down syndrome among 94,610 births was 0.87 per 1000, or 1 per 1150. Screening of 112,269 newborns for aminoacid disorders showed four disorders to be the commonest--tyrosinemia, maple syrup urine disease and phenylketonuria. Screening of cases of mental retardation for aminoacid disorders revealed four to be the commonest--hyperglycinemia, homocystinuria, alkaptonuria, and maple syrup urine disease. Metabolic studies of cases of mental retardation in AIIMS, Delhi and KEM Hospital, Mumbai, demonstrated that common disorders were those of mucopolysaccharides, lysosomes, Wilson disease, glycogen storage disease and galactosemia. It is estimated that beta- thalassemia has a frequency at birth of 1:2700, which means that about 9,000 cases of thalassemia major are born every year. Almost 5200 infants with sickle cell disease are born every year. Disorders, which deserve to be screened in the newborn period, are hypothyroidism and G-6-PD deficiency, while screening for aminoacid and other metabolic disorders could presently be restricted to symptomatic infants.

Amino Acid Metabolism, Inborn Errors↗

Cytogenetics investigation in childhood chronic myeloid leukemia.

Cytogenetics investigations, mostly from peripheral blood, were carried out in 30 children with CML. Amongst a sample of 30 patients, 18 had chronic myeloid leukemia of adult variety (ACML), while the remaining 12 children had the juvenile type of chronic myeloid leukemia (JCML). Sixteen (88.9%) out of the 18 patients suffering from ACML tested positive for the classical Philadelphia chromosome translocation t(9; 22). Of the remaining two ACML patients, one tested positive for t(9; 13; 22) while no visible chromosomal changes were observed in the other patient. The activity of Nucleolar Organizer Region (NOR) was significantly reduced in 11 (61.1%) of the 18 patients suffering from ACML, when compared to that of 21 normal healthy controls. Ten out of the 12 patients suffering from JCML had normal karyotypes, while monosomy 8 and 21 q deletion were seen in the remaining two patients respectively. Amongst the 30 CML patients, chromosomal abnormalities were observed in 19 patients. Variant Philadelphia chromosome translocation (9; 13; 22) and monosomy B were observed in ACML and JCML, respectively. In two ACML patients, cytogenetic studies were helpful in diagnosis of the disease.

Adolescent↗