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Biomedical subjects

P S Menon

Publications and source records attributed to P S Menon.

At least 19 recordsLinked to original sources
PubMed2001

Novel mutations of MYO15A associated with profound deafness in consanguineous families and moderately severe hearing loss in a patient with Smith-Magenis syndrome.

Mutations in myosin XVA are responsible for the shaker 2 ( sh2) phenotype in mice and nonsyndromic autosomal recessive profound hearing loss DFNB3 on chromosome 17p11.2. We have ascertained seven families with profound congenital hearing loss from Pakistan and India with evidence of linkage to DFNB3 at 17p11.2. We report three novel homozygous mutations in MYO15A segregating in three of these families. In addition, one hemizygous missense mutation of MYO15A was found in one of eight Smith-Magenis syndrome (del(17)p11.2) patients from North America who had moderately severe sensorineural hearing loss.

Abnormalities, Multiple↗
PubMed2001

Factor IX gene polymorphisms in Indian population.

Hemophilia B is an X-linked, recessive disorder of hemostasis, caused by a defect in coagulation factor IX. To date, several restriction fragment length polymorphisms (RFLPs) have been identified within the gene for human factor IX. The incidence of these RFLPs differs significantly in different populations. In the present study, we analyzed the heterozygosity frequency and the allele frequency of three common intra- and extragenic polymorphic sites of the factor IX gene in Indian population. The main objective was to test the informativeness of two intragenic markers Dde I and Xmn I and one extragenic marker Hha I for carrier detection and prenatal diagnosis. The method used was polymerase chain reaction (PCR) and RFLP, which is economical yet simple to perform. In Indian population Dde I marker showed an informativeness of 69.0% followed by 38.0% for Hha I and 23.0% for Xmn I. The cumulative informativeness of these three markers was found to be 80 to 82%. A comparison of the heterozygosity rates of these three markers with the other ethnic groups showed that Indian population had almost similar pattern with the Caucasians and American blacks but differed significantly from the Orientals including Japanese, Chinese and Malays.

Deoxyribonucleases, Type II Site-Specific↗
PubMed2001

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↗
PubMed2001

Autoimmune thyroid disease in Indian children with type 1 diabetes mellitus.

The objective of the present study was to determine the prevalence of autoimmune thyroid disease in Indian children with type 1 diabetes mellitus by the assay of antibodies to thyroid peroxidase and thyroglobulin. The study population consisted of 35 children with type 1 diabetes mellitus and 32 healthy age- and sex-matched control children. Thyroid peroxidase antibodies (TPO) were determined by ELISA and thyroglobulin antibodies (TGA) by passive hemagglutination. Thyroid function tests and tests of glycemic control were also performed. These assays were repeated after six months and one year. TPO were observed in 19 (54.3%) patients compared to three (10%) controls, and TGA in 11 (31.4%) patients and none of the controls. Both these observations were statistically significant with p=0.0002 for TPO and 0.0016 for TGA. The prevalence of these antibodies was not different in boys and girls and did not change with the duration of diabetes. All patients who were positive for TGA were also positive for TPO. Thyroid function tests were abnormal in one patient who was found to have Hashimoto's thyroiditis. There is a definite need to screen all diabetic children for thyroid antibodies and carefully follow up those patients in whom these antibodies are positive.

Autoimmune Diseases↗
PubMed2000

Infantile-onset leukoencephalopathy with discrepant mild clinical course.

Four children characterised by megalencephaly and cerebral leukoencephalopathy with infantile onset, defined on the basis of clinical and neuroimaging findings are reported. The course of the disease is characterised by stabilization of the macrocephaly and slow clinical deterioration. The CT scan findings include supratentorial diffuse hypodensities in the white matter and swelling. The characteristic MRI findings include the discrepant severity in comparison with the clinical picture, diffuse supratentorial white matter abnormalities with subcortical cysts. The basic defect of the disease is unknown. Considering the high rate of consanguinity among the parents and the presence of two affected sibs in one family, an autosomal recessive inheritance is assumed. We report four unrelated cases of this entity.

Brain↗
PubMed2000

Fraser-cryptophthalmos syndrome.

Fraser or Cryptophthalmos syndrome is a variable syndrome to the extent that cryptophthalmos might not be present in all cases. However, the main features are a "hidden eye", other craniofacial abnormalities, renal abnormalities, syndactyly and abnormal genitalia. It may be classified as isolated cryptophthalmos or cryptophthalmos sequence and cryptophthalmos syndrome. The cryptophthalmos syndrome has an autosomal recessive mode of inheritance. Isolated cryptophthalmos has been reported as an autosomal dominant trait. Prenatal diagnosis is possible using ultrasonography and fetoscopy. We report three cases of cryptophthalmos. One with renal agenesis had cryptophthalmos syndrome and the other two had isolated cryptophthalmos or cryptophthalmos sequence.

Abnormalities, Multiple↗
PubMed2000

I-cell disease (Mucolipidosis II).

I-cell disease (Mucolipidosis II) is one of the lysosomal storage diseases which presents in the neonatal period, and within six months will phenotypically resemble the severe forms of the group of disorders called the "mucopolysaccharidoses" but without mucopolysacchariduria. In Mucolipidosis II, fibrocytes exhibit "abnormal lysosomes". Activities of several lysosomal enzymes are low in fibroblast cultures but high in mucolipidosis II serum. We present a patient with I-cell disease diagnosed on the basis of clinical, radiological and biochemical features. The mother of this child was pregnant and the fetus was also found to be affected.

Child, Preschool↗
PubMed2000

Insulin analogues and management of diabetes mellitus.

The introduction of insulin analogues, of which insulin lispro is the prototype, marks a very important milestone in the management of patients with diabetes mellitus. It differs from regular human insulin in its quicker onset and shorter duration of action. In various clinical trials, insulin lispro was found to be superior to regular human insulin in controlling postprandial hyperglycemia without increasing the risk of hypoglycemia. It improved the quality of life of diabetic patients by providing more flexibility to meal plans. Recently, another short acting insulin analogue called insulin aspart has been tried in clinical studies with benefits similar to insulin lispro. The turn of the millennium is now witnessing the development of long acting insulin analogues like insulin glargine, which can provide continuous low-level basal insulin concentrations similar to natural settings. In this review, we discuss the potential of insulin analogues in the modern management of diabetes with emphasis on insulin lispro.

Diabetes Mellitus↗
PubMed2000

Diabetes mellitus in newborns and infants.

Diabetes mellitus is uncommon in infancy and newborn period. The two common forms seen are the transient and permanent forms of diabetes mellitus of the newborn. They have to be differentiated from the transient hyperglycemic states (Blood sugar > 125 mg/dl) seen in newborns who receive parenteral glucose infusions and in those with septicemia and CNS disorders. Transient diabetes mellitus of the newborn (TDNB) is defined as hyperglycemia occurring within the first month of life lasting at least 2 weeks and requiring insulin therapy. Most of these cases resolve spontaneously by 4 months. It has a reported incidence of 1 in 45,000 to 60,000 live births. The most likely etiology is a maturational delay of cAMP mediated insulin release. The clinical features include small for datedness, proneness for birth asphyxia, open-eye alert facies, dehydration, emaciation, polyuria and poydipsia. These children are prone to septicemia and urinary tract infections. They have hyperglycemia, glucosuria, absent or mild ketonuria, low basal insulin, C-peptide and IGF-1 levels. Treatment consists of hydration and judicious administration of insulin with close monitoring. Thirty percent of these children are likely to develop permanent neonatal diabetes. Compared to transient form, permanent diabetes mellitus is uncommon. It is usually due to pancreatic dysgenesis often associated with other malformations and rarely due to type 1 diabetes mellitus. The diagnosis is based on the demonstration of both exocrine and endocrine pancreatic dysfunction. These children are managed as type 1 diabetes mellitus. They are prone to develop the vascular complications of diabetes at an earlier date.

Diabetes Mellitus↗
PubMed2000

Management of undescended testis.

The term cryptorchidism indicates a testis, which has failed to descend to the scrotum and is located at any point along the normal path of descent or at an ectopic site. Hormones play a pivotal role in testicular descent except during the migration to the level of internal inguinal ring. Cryptorchidism is present in about 4.5% of newborns with a higher incidence in preterms. The incidence decreases to 1.2% by the first year. It is classified as palpable and impalpable. The most common site of an ectopic testis is superficial inguinal pouch. Retractile testis is often bilateral and most common in boys between 5 and 6 years of age. Hypospadias and inguinal hernias are the most common associated anomalies seen with undescended testis. A thorough clinical examination helps in arriving at the etiology. A short hCG stimulation test helps to exclude anorchia. Different imaging techniques are of little help in diagnosis and require the help of an experienced radiologist. Laparoscopy has an important role in the diagnosis and management of undescended testis. The common complications include torsion and atrophy of testis. Infertility is seen in about 40% of unilateral and 70% of bilateral cryptorchidism. Undescended testis is 20 to 40 times more likely to undergo malignant transformation than normal testis. Both hCG and GnRH have been used with limited success in these children. All boys with cryptorchidism should be referred to a pediatric surgeon before 2 years of age. These children should be followed up every year after surgery to identify testicular tumors.

Child, Preschool↗
PubMed2000

The child with micropenis.

Micropenis refers to an extremely small penis with a stretched penile length of less than 2.5 SD below the mean for age or stage of sexual development. It should be differentiated from a buried or hidden penis and aphallia. It is important to use a standard technique of stretched penile measurement and nomograms for age to identify children with micropenis. All children above 1 year of age with a stretched penile length of less than 1.9 cm need evaluation. Based on etiology they can be classified as hypogonadotropic hypogonadism (hypothalamic or pituitary failure), hypergonadotropic hypogonadism (testicular failure), partial androgen insensitivity syndrome and idiopathic groups. The help of a pediatric endocrinologist, geneticist, pediatric surgeon and/or urologist is often necessary. Growth velocity is an important determinant of associated hypothalamic or pituitary pathology. GnRH and/or hCG stimulation tests are often helpful in evaluating the etiology. Similarly chromosomal studies are indicated in a few. Often the diagnosis is inferred by the presence of clinical features suggestive of a syndrome usually associated with hypogonadotropic hypogonadism. Irrespective of the underlying cause a short course of testosterone should be tried in patients with micropenis and an assessment of the penis to respond should be made. Transdermal DHT has also been reported to be effective in prepubertal children. Children with hypopituitarism and GH deficiency respond to appropriate hormonal therapy. Surgical correction is not indicated in the common endocrine types of micropenis. Many studies have shown that most testosterone treated children have satisfactory gain in length of penis and sexual function. Thus sexual reassignment is done very infrequently now.

Adult↗
PubMed2000

Factor VIII gene polymorphisms in the Asian Indian population.

Little is known about the heterozygous frequency of factor VIII gene markers in the Asian Indian population. The objective of this study was to establish the heterozygous frequency of polymorphic markers within and flanking the factor VIII gene in Indians and identify those most informative for carrier screening and prenatal diagnosis. Factor VIII gene polymorphism analysis at intragenic and extragenic sites was carried out by the polymerase chain reaction (PCR) method and Southern blot procedure. Sixty-three Asian Indian haemophiliacs and their families were screened. A control group of 150 women from nonhaemophilic families were screened for two markers, HindIII and BclI. Among the intragenic markers studied, the HindIII restriction fragment length polymorphism (RFLP) showed the highest heterozygous frequency (0.52) followed by the intron 13 (0.47) and intron 22 (0. 44) short tandem repeats (STRs). Among extragenic markers, TaqI had the highest heterozygous frequency (0.75) followed by BglII (0.54). The intron 22 inversion mutation was observed in eight (40%) of 20 severe cases. In the population studied the most diagnostic polymorphisms were the intragenic markers, intron 22 (70%) STR followed by the intron 13 (52%) STR and HindIII (52%) RFLP, and the TaqI (50%) extragenic marker. Application of HindIII, BclI and the intron 22 dinucleotide repeat combined were diagnostic in 87.2% of haemophilia A families studied.

Alleles↗
PubMed1999

Cardiac function in hypothyroid children: effect of replacement therapy.

OBJECTIVE: To evaluate prospectively cardiac function in children with primary hypothyroidism before and after replacement therapy with L-thyroxine. DESIGN: Prospective clinical and laboratory cardiac evaluation of children with hypothyroidism before and after therapy. SETTING: Hospital based. SUBJECTS: 20 consecutive children aged 6 months - 14 years with primary hypothyroidism. METHODS: Assessment of cardiac status by clinical, radiological, ECG, echocardiography, M-mode and 2 dimensional echo-Doppler study and phonocardiography for systolic and diastolic functions and structural anomalies. RESULTS: Indices of myocardial contractility like ejection fraction (EF), velocity of circumferential fibre shortening (VCF) did not change with therapy. However, systolic time intervals, both left ventricular (before therapy 0.32+/-0.03 msec; after therapy 0.25+/-0.03 msec; p <0.001) showed a significant change. In diastolic functions, isovolumic relaxation time fell from 62+/-9 msec before therapy to 50+/-5 msec after therapy (p <0.001). Pericardial effusion was found in 10 children before treatment which disappeared in 7 following therapy. CONCLUSION: Subtle evidence of alteration of myocardial function is thus seen in children with primary hypothyroidism which reverses with treatment.

Adolescent↗