Syndrome of Congenital Insulin Resistance Caused by a Novel INSR Gene Mutation

Mutations in the INSR gene result in rare inherited syndromes causing insulin resistance, such as leprechaunism (Donohue syndrome), Rabson-Mendenhall syndrome and insulin resistance type A. Leprechaunism is an autosomal recessive disorder associated with extreme insulin resistance that leads to hyperinsulinemia, impaired glucose homeostasis, fasting hypoglycemia and postprandial hyperglycemia. Impaired insulin action causes prenatal and postnatal growth retardation. Lipoatrophy, dysmorphic facies, hypertrichosis, macrogenitosomia and hypertrophy of internal organs are also present. A male infant with congenital insulin resistance was born at term after a normal pregnancy with a weight of 1905 g (<3 c), a length of 48 cm (<3 c), and an Apgar score of 10. Intrauterine growth retardation, transient hypoglycemia, pneumonia, urinary tract infection and heart defects [patent foramen ovale (PFO); patent ductus arteriosus (PDA)] were diagnosed after birth. At 5 weeks of age, he was admitted to the regional hospital with severe fever, diarrhea and dehydration. Hyperglycemia was observed (672 mg/dL), and insulin was administered. He was referred to a hospital at 7 weeks of age for suspected neonatal diabetes and hypertrophic cardiomyopathy. The physical examination revealed a loud systolic heart murmur, tachycardia, tachypnea, dysmorphic facies, hypertrichosis, acanthosis nigricans, hypotonia, swollen nipples and enlarged testicles. Glycemic fluctuations (50-250 mg/dL) were observed. The serum insulin concentration was high (maximum 1200 IU/mL) at normoglycemia. Ultrasound of the heart confirmed progressive hypertrophic cardiomyopathy. Leprechaunism was confirmed by genetic analysis of INSR, in which a novel c.320C>G; p. Thr107Arg homozygous missense mutation was found in exon 2.

Next- generation sequencing is an effective method for diagnosing patients with different forms of monogenic diabetes

AIM

Monogenic diabetes (MD) represents 5-7% of antibody-negative diabetes cases and is a heterogeneous group of disorders.

METHODS

We used targeted next-generation sequencing (NGS) on Illumina NextSeq 550 platform involving the SureSelect assay to perform genetic and clinical characteristics of a study group of 684 individuals, including 542 patients referred from 12 Polish Diabetes Centers with suspected MD diagnosed between December 2016 and December 2019 and their 142 family members (FM).

RESULTS

In 198 probands (36.5%) and 66 FM (46.5%) heterozygous causative variants were confirmed in 11 different MD-related genes, including 31 novel mutations, with the highest number in the GCK gene (206/264), 22/264 in the HNF1A gene and 8/264 in the KCNJ11 gene. Of the 183 probands with MODY1-5 diabetes, 48.6% of them were diagnosed at the pre-diabetes stage and most of them (68.7%) were on diet only at the time of genetic diagnosis, while 31.3% were additionally treated with oral hypoglycaemic drugs and/or insulin.

CONCLUSIONS

In summary, the results obtained confirm the efficacy of targeted NGS method in the molecular diagnosis of patients with suspected MD and broaden the spectrum of new causal variants, while updating our knowledge of the clinical features of patients defined as having MD.

The presence of eye defects in patients with Turner syndrome is irrespective of their karyotype

OBJECTIVE

Published data on eye disorders in patients with Turner syndrome (TS) are limited. We aimed to evaluate the prevalence of eye disorders in patients with TS and assess the association with patient karyotype.

DESIGN

Cross-sectional, observational study.

PATIENTS

Eighty-two patients with TS.

MEASUREMENTS

We evaluated visual acuity (distance and proximity), intraocular pressure, optic system refraction, orthoposition, frontal eye segment, the eye fundus and colour vision. For eye fundus abnormalities, we conducted ultrasound examinations, visual field evaluations and fluorescein angiography. We statistically tested the association between the prevalence of eye disorders and karyotype.

RESULTS

50 (61%) patients had monosomy X; 9 (11%) had mosaicism with a normal 46,XX line; 21 (26%) had structural aberrations; and 2 patients (2%) had other chromosomal abnormalities. Eye disorders were diagnosed in 43 (52%) patients, with 29 (35%) patients having multiple eye defects. Defects related to impaired vision were the most common (44%), followed by strabismus (21%), changes in the posterior eye segment (6%), red-green colour deficiency (5%), changes in the anterior eye segment (5%) and nystagmus (4%). Amblyopia was diagnosed in 13 patients (16%). The most common combinations of ophthalmological defects were hypermetropia and astigmatism with or without other eye problems (12 patients). We found no association between the presence of eye defects and karyotype.

CONCLUSIONS

Detection of eye abnormalities is necessary in all patients directly after being diagnosed with TS to prevent irreversible deterioration of eye function and permanent poor vision. All girls with TS, irrespective of their karyotype, should be referred to an ophthalmologist.

A novel p.E311K mutation of thyroid receptor beta gene in resistance to thyroid hormone syndrome, inherited in autosomal recessive trait

Resistance to thyroid hormone (RTH) syndrome is caused by mutations in THRB gene and is inherited mainly as an autosomal dominant trait with dominant negative effect. Most of up-to-now described RTH cases were heterozygous. We studied a 19-year-old woman presenting severe mental impairment, hyperkinetic behavior, learning disability, hearing loss, tachycardia, goiter, strabismus, nystagmus, and normal stature. The laboratory findings revealed elevated TSH, T3, and T4 serum levels. Her parents were healthy with normal serum level of TSH, fT3, and fT4. Sequence based prediction of a substitution was analyzed by SDM, PolPhen, and SNAP software whereas structural visualizations were performed in UCSF Chimera. We found a novel mutation in THRB gene in position 1216 (G to A transition, codon 311) resulting in novel Glu-311-Lys (p.E311K) substitution, homozygous in proband presenting with severe symptoms of RTH and heterozygous in both of her healthy parents, thus suggesting autosomal recessive mode of inheritance. p.E311K substitution was not found in 50 healthy, unrelated individuals. p.E311K was shown to be deleterious by SDM, PolPhen, and SNAP software. Structural visualizations of mutated protein performed by UCSF Chimera software disclosed a loss of hydrogen bonds between E311, R383, and R429 along with abnormal residue-residue contact between K311 and L377. This is a very rare case of a homozygous mutation in a patient with severe symptoms of RTH and lack of symptoms in both heterozygous parents. Although, computational analyses have provided the evidence that p.E311K substitution may affect THRB function, lack of dominant negative effect typical for THRB mutations could not be explained by structure-based modeling. Further in vitro analysis is required to assess the functional consequences of this substitution.

Visfatin in juvenile obesity - the effect of obesity intervention and sex

BACKGROUND

The association of visfatin, an adipocytokine relevant to the development of inflammation and metabolic disorders, with juvenile obesity needs to be re-established as previously used tests occurred to be nonspecific.

OBJECTIVE

To evaluate visfatin association with a metabolic profile of 88 overweight/obese and 26 lean children/adolescents as well as changes in its levels following weight reduction programme (diet + enhanced physical activity ± metformin).

DESIGN

A case-control and cohort study.

RESULTS

Visfatin was higher in obese than lean and overweight individuals (2·07 vs. 1·53 and 1·47 ng mL(-1) , P = 0·034). Of metabolic syndrome components, central obesity combined with either insulin resistance (IR) or hyperinsulinemia (HI) was associated with increases in circulating visfatin. In girls, visfatin correlated with leptin (r = 0·40, P = 0·009) and thiols (r = -0·36, P = 0·009), which explained 24% in visfatin variability. In boys, visfatin correlated with waist circumference (r = 0·36, P = 0·036), BMI% (r = 0·38, P = 0·025), whole body insulin sensitivity index (r = -0·36, P = 0·036), IL-6 (r = 0·38, P = 0·024) and thiobarbituric acid reactive substances (TBARS) (r = 0·52, P = 0·001), of which IL-6 and TBARS were independent predictors of visfatin elevation, explaining 42% in data variability. Visfatin was significantly lower following weight reduction programme than at baseline (1·43 vs. 1·83 ng mL(-1) , P = 0·033). Visfatin reduction correlated neither with changes in metabolic parameters nor was it affected by metformin. ΔVisfatin correlated exclusively with baseline visfatin (r = 0·612, P < 0·0001), which explained 38% in data variability.

CONCLUSIONS

Central obesity combined with HI/IR contributes to visfatin elevation. Visfatin association with metabolic/biochemical variables is gender dependent. Diet + enhanced physical activity are effective in visfatin reduction, the degree of which depends on baseline visfatin.

The effect of a one-year weight reduction program on serum uric acid in overweight/obese children and adolescents

BACKGROUND

Hyperuricemia may underlie obesity and related disorders, but the impact of weight reduction and metformin on serum uric acid (sUA) in Caucasian children/adolescents is unknown.

METHODS

One hundred and thirteen children/adolescents were enrolled (83 completed) into 1-year weight reduction program (diet+exercise) without or with metformin. Anthropometric and biochemical measurements were conducted at baseline and at the end of follow-up (13 ± 3 months).

RESULTS

sUA decreased in 86% females and 67% males. Significantly more patients substantially (≥ 10%) reduced their sUA than body mass index (BMI)%. In females, sUA decreased regardless of type of intervention, but more markedly in the metformin group, and ΔsUA correlated positively with ΔBMI%, ΔWHtR (waist-to-height ratio), Δinsulin, ΔHOMA (homeostasis model of assessment), and Δtriglycerides/high density lipoprotein (HDL), but correlated negatively with baseline sUA, HOMA, insulin, and triglycerides/HDL. Of these, metformin treatment, baseline sUA, and ΔBMI% were independent predictors of sUA reduction, explaining 77% of data variability. In males, sUA reduction was significant in the metformin group only, and negatively correlated with ΔWHR (waist-to-hip ratio), ΔWHtR, Δleptin, baseline sUA, and waist circumference. Of these, baseline sUA and ΔBMI% were independent predictors of sUA reduction, explaining 69% of data variability. Except for sUA, females reduced their BMI%, waist circumference, triglycerides, triglycerides/HDL and increased HDL, while males reduced total cholesterol.

CONCLUSIONS

A longitudinal weight reduction program encompassing diet/exercise with or without metformin was more efficient in reducing sUA than weight and its effect on sUA and other metabolic parameters differed between genders. Weight loss did not condition sUA reduction, which was strongly dependent on baseline levels. The sUA reducing effects of metformin may contribute to its effects on blood pressure-lowering and endothelial function-improving properties in females.

Circulating adipocyte fatty acid-binding protein, juvenile obesity, and metabolic syndrome

Adipocyte fatty acid-binding protein (A-FABP) links obesity and metabolic syndrome (MetS) and might be targeted in future therapies. Its utility as a MetS biomarker has been suggested in adults but has not been examined in children/adolescents. Our objectives were to identify metabolic parameters associated with A-FABP elevation in children and adolescents and to evaluate the effect of obesity intervention and A-FABP diagnostic utility. A-FABP and anthropometric, metabolic, and inflammatory indices were measured in 31 lean and 114 overweight/obese children and adolescents and reassessed after obesity intervention (1 year; diet and enhanced physical activity, with or without metformin). A-FABP was significantly higher in overweight/ obese than lean individuals, where it correlated with insulin, waist circumference (WC), and 2-h glucose independent of body mass index (BMI), age, gender, and developmental stage. The pattern of A-FABP associations differed between sexes. As a MetS indicator, A-FABP had 68% accuracy. The weight reduction program was effective in reducing A-FABP, BMI%, WC, triglycerides, and cholesterol. In conclusion, elevation in A-FABP is associated with MetS components independent of BMI status and can be reduced by diet and enhanced physical activity. A-FABP as a single MetS biomarker has a moderate accuracy.

Gender-specific association of serum uric acid with metabolic syndrome and its components in juvenile obesity

BACKGROUND

Hyperuricemia has been implicated in the pathogenesis of obesity and related metabolic abnormalities. Studies on the association between serum uric acid (sUA) and metabolic syndrome (MetS) in juvenile obesity are scant. The effect of gender has not been evaluated.

METHODS

sUA (uricase method), anthropometric and biochemical indices were measured in gender-stratified children/adolescents consisting of 113 overweight/obese and 71 lean individuals.

RESULTS

In males, sUA was significantly elevated in overweight as well as obese patients. sUA was strongly associated with obesity indices and reflected sexual development, decreases in high density lipoprotein-cholesterol, and moderately, the number of MetS components. Waist circumference (WC) and Tanner stage explained 40% of sUA variability. Controlling for body mass index (BMI) and other MetS components, sUA was associated with abdominal obesity, explaining 30% of variability in WC. In females, sUA was significantly increased in obesity, high blood pressure (BP), and MetS and corresponded with the number of MetS components, indices of glucose metabolism, triglycerides (TG), and the atherogenecity index. Insulin-resistance (IR) (homeostasis model assessment; HOMA) and high BP explained 29% of sUA variability, whereas sUA, while controlling for BMI, age, and other MetS components, was associated with hypertriglyceridemia, hyperglycemia, high BP, and abdominal obesity. IR mediated the associations with high TG and glucose.

CONCLUSIONS

The association between sUA and MetS components in juvenile obesity is gender-specific, with females being related more closely and to more metabolic abnormalities. It may explain why, despite its lower concentrations, sUA is an independent predictor of mortality from all causes and from vascular diseases exclusively in females. Our findings may help in identifying metabolic abnormalities which may possibly be targeted by reducing sUA in males and females.

Efficacy and safety of sulfonylurea use in permanent neonatal diabetes due to KCNJ11 gene mutations: 34-month median follow-up

BACKGROUND

Recently, many patients with Kir6.2-related permanent neonatal diabetes mellitus (PNDM) have been successfully transferred from insulin therapy to sulfonylurea (SU) treatment. The long-term efficacy and safety of SU treatment in PNDM patients, however, have not yet been determined.

METHODS

We monitored glycemic control and the occurrence of potential side effects in 14 Kir6.2-related PNDM patients from Poland (median age, 12.0 years; range, 5-50 years) who were transferred to SU therapy at least 2 years ago. Three of the 14 patients were lost to follow-up, whereas for the remaining 11 individuals the median follow-up was 34 months (range, 27-51 months).

RESULTS

The initial reduction of glycated hemoglobin (HbA1c) after the switch to SU (approximately 3-6 months post-transfer) was 1.68% (range, 0.3-3.7%), and good metabolic control was maintained over the entire period of observation with an average HbA1c level of 6.0% (range, 5.3-6.7%) at the last visit. This was accompanied by a substantial drop in SU dose by 0.24 mg/kg, which constituted a 38.0% decrease. A rapid progression of retinal changes was observed in one patient, a 34-year-old woman at the beginning of the observation, with preexisting proliferative diabetic retinopathy. No causal relationship between these changes and SU treatment could be proven. Neither serious side effects nor progression of diabetes complications was observed in any other patients. No detrimental effect on growth in the observed minors was recorded.

CONCLUSIONS

In summary, the switch from insulin therapy to SU treatment in PNDM related to KCNJ11 mutations was found to be an efficient and safe therapeutic method over a period of 34-month median follow-up. Although no serious side effects were associated with SU treatment, their use in Kir6.2 PNDM requires further attention, particularly in children, adolescents, and patients with advanced chronic diabetes complications.

Mutations in the ABCC8 (SUR1 subunit of the K(ATP) channel) gene are associated with a variable clinical phenotype

OBJECTIVE

Mutations in the ABCC8 gene encoding the SUR1 subunits of the beta-cell K-ATP channel cause neonatal diabetes (ND) mellitus. We aimed to determine the contribution of ABCC8 gene to ND in Poland, to describe the clinical phenotype associated with its mutations and to examine potential modifying factors.

PATIENTS

The Nationwide Registry of ND in Poland includes patients diagnosed before 6 months of age. In total 16 Kir6.2 negative patients with ND, 14 permanent and 2 relapsed transient, were examined.

MEASUREMENTS

ABCC8 gene mutations were detected by direct sequencing. Mutation carriers' characteristics included clinical data and biochemical parameters. In addition, we performed the hyperinsulinaemic euglycaemic clamp and tested for islet-specific antibodies in diabetic subjects.

RESULTS

We identified two probands with permanent ND (one heterozygous F132V mutation carrier and one compound heterozygote with N23H and R826W mutations) and two others with relapsed transient ND (heterozygotes for R826W and V86A substitutions, respectively). One subject, a heterozygous relative with the R826W mutation, had adult onset diabetes. There were striking differences in the clinical picture of the mutation carriers as the carrier of two mutations, N23H and R826W, was controlled on diet alone with HbA(1c) of 7.3%, whereas the F132V mutation carrier was on 0.66 IU/kg/day of insulin with HbA(1c) of 11.7%. The C-peptide level varied from 0.1 ng/ml (F132V) to 0.75 ng/ml (V86A). We also observed a variable insulin resistance, from moderate (M = 5.5 and 5.6 mg/kg/min, respectively, in the two R826W mutation carriers) to severe (M = 2.6 mg/kg/min in the F132V mutation carrier). We were able to transfer two patients off insulin to sulphonylurea (SU) and to reduce insulin dose in one other patient. Interestingly, there was no response to SU in the most insulin resistant F132V mutation carrier despite high dose of glibenclamide. All examined auto-antibodies were present in one of the subjects, the V86A mutation carrier, although this did not seem to influence the clinical picture, as we were able to transfer this girl off insulin.

CONCLUSION

Mutations in SUR1 are the cause of about 15% of Kir6.2 negative permanent ND in Poland. The clinical phenotype of SUR1 diabetic mutation carriers is heterogeneous and it appears to be modified by variable sensitivity to insulin.

Diagnostic potential of oxidative stress markers in children and adolescents with type 1 diabetes

OBJECTIVES

To validate the diagnostic utility of oxidative stress markers in the evaluation of young type 1 diabetics, as suggested elsewhere.

DESIGN

Advanced oxidation protein products (AOPP), thiobarbituric acid-reactive substances (TBARS) and total antioxidant status (TAS) were measured in sera from diabetics, their siblings and controls, with diagnostic potential evaluated by ROC analysis, and related to diabetes clinical parameters.

RESULTS

In diabetics AOPP and TBARS were elevated, TAS decreased. Similar alterations were observed for AOPP and TAS in their siblings. AOPP and TAS were good indicators of diabetes. AOPP and TBARS correlated with HbA1C (independent predictor), but were poor markers of non-adequate glycemic control. The cardiovascular disease risk factors were independent predictors of TBARS concentrations.

CONCLUSIONS

AOPP accumulation and TAS reduction seem to precede diabetes and might be considered as susceptibility indicators in relatives, but not as diabetes markers in general population (no diabetes specificity has been shown). Application in monitoring of metabolic control is not validated.

Distribution of Ca.LSU intron and acid protease production by Candida albicans strains isolated from gastrointestinal tract of diabetes children

The association between the presence of self-splicing intron Ca.LSU and proteolytic activity of Candida albicans isolates was tested. Study included 95 C. albicans strains isolated from gastrointestinal tract of diabetes children. The strains with the intron (genotype B) displayed a significantly higher proteolytic activity (385.2+/-192U/L) than did strains without intron (genotype A) (119+/-115U/L) (p = 0.0000048).

Sudden hearing loss as a first complication of long-standing Type 1 diabetes mellitus: a case report

The term 'sudden hypoacusis' describes a hearing loss of a rapid onset and unknown origin that can progress to severe deafness. Its pathophysiology is still unknown, the proposed aetiological mechanisms being vascular disease or autoimmune reaction. We present the case of a 19-year-old woman with Type 1 diabetes mellitus who experienced sudden hearing loss on her right side. She had no complications related to diabetes. After being referred to the hospital she was diagnosed with sudden sensorineural right-sided hearing loss accompanied by high frequency tinnitus. After administration of vasoactive drugs, there was partial improvement after 7 days, followed by gradual improvement over the next 4 weeks to 5 months. The tinnitus did not disappear completely. We conclude that hearing organ disturbances can be present in Type 1 diabetes and represent an early complication.

Are there any disturbances in vestibular organ of children and young adults with Type I diabetes?

AIMS/HYPOTHESIS

The aim of the work was to evaluate the vestibular organ condition in children and young adults suffering from Type I (insulin-dependent) diabetes mellitus.

METHODS

The group examined consisted of 95 children and young adults aged from 6 to 28 years with Type I diabetes diagnosed. The diabetic group was divided into subgroups according to duration of the disease, compensation of the disease, and presence and character of hypoglycaemic incidents, and presence of diabetic complications. The control group consisted of 44 healthy children and young adults aged 6 to 28 years. After collecting detailed medical history in each case an electronystagmographic test was performed using the computed two-canal electronystagmographer.

RESULTS

Within the diabetic group 6 patients complained about vertigo and balance disorders. Spontaneous nystagmus occurred in 10 cases, positional one in 21 cases. Impaired optokinesis occurred in 36 cases and impaired eye tracking test in 33 cases. In caloric tests there was partial canal paresis in 4 cases and directional preponderance in 7 cases.

CONCLUSION/INTERPRETATION

Metabolic disturbances present in Type I diabetes cause disturbances in different parts of vestibular organ but mostly in its central part. Comparing disturbances in the vestibular organ with clinical and biochemical parameters characterising diabetes, the range of vestibular organ impairment in diabetes mellitus type 1 seems to depend mainly on the presence and character of hypoglycaemic incidents and the duration of the disease and to some extent on the compensation of diabetes.