Is the alpha-galactosidase A variant p.Asp313Tyr (p.D313Y) pathogenic for Fabry disease? A systematic review.

The identification of pathogenic GLA variants plays a central role in the establishment of a definite Fabry disease (FD) diagnosis. We aimed to review and interpret the published data on the p.Asp313Tyr (p.D313Y) variant pathogenicity and clinical relevance. We performed a systematic review of peer-reviewed publications and case-reports on individuals and populations harbouring the p.Asp313Tyr variant. Overall, 35 studies were included in this review. We collected data regarding the clinical manifestations, alpha-galactosidase A enzyme activity, levels of the biomarkers globotriaosylceramide (Gb3 ) and sphingosine-globotriaosylceramide (lyso-Gb3 ) and histological findings of p.Asp313Tyr carriers. The prevalence of p.Asp313Tyr in populations at risk for FD (kidney, heart, neurologic disorders, or symptomatic populations) was calculated. We found high residual enzyme activity, low frequency of clinical features specific for FD, non-elevated lysoGb3 /Gb3 concentrations and lack of intracellular Gb3 accumulation in biopsies in the p.Asp313Tyr carriers. The prevalence of the variant in populations at risk for FD was comparable to the reported frequency in the general population. A possible higher frequency was only observed in neurologic disorders. p.Asp313Tyr can be classified as neutral or variant of unknown significance. Further investigations will be helpful to clarify a possible association between the variant and manifestations in the brain vessels.

Age-related renal function decline in Fabry disease patients on enzyme replacement therapy: a longitudinal cohort study.

BACKGROUND: Nephropathy is common in Fabry disease (FD). Prior studies of renal function during enzyme replacement therapy (ERT) have primarily used estimated glomerular filtration rate (eGFR). We studied the attrition of renal function in FD by measured GFR (mGFR) and urine protein excretion, and explored the influence of age. METHODS: This was a long-term observational study of a nationwide, family-screened cohort of FD patients. All Danish genetically verified FD patients on ERT, without end-stage renal disease at baseline and with three or more mGFR values were included. RESULTS: In all, 52 patients with consecutive mGFR values (n = 841) over median 7 years (range 1-13) were evaluated. Blood pressure remained normal and urine protein excretion was unchanged. Plasma globotriaosylceramide (Gb-3) levels normalized while plasma lyso-Gb-3 remained abnormal in 34% of patients. Baseline mGFR was 90 ± 3 mL/min/1.73 m2 and rate of renal function loss 0.9 ± 0.2 mL/min/1.73 m2/year. Baseline eGFR was 97 ± 5 mL/min/1.73 m2 and rate of renal function loss 0.8 ± 0.3 mL/min/1.73 m2/year. mGFR was age- adjusted to renal healthy non-FD subjects, giving a standard deviation score of -0.8 ± 0.2 with an annual slope of -0.03 ± 0.01 (P = 0.099), without differences between genders. Age grouping of age-adjusted data showed exaggerated renal function loss with age. Urine albumin-creatinine ratio (UACR) >300 mg/g was associated with faster renal function loss, independent of baseline mGFR, age and gender. CONCLUSIONS: ERT-treated FD patients did not have a faster attrition of renal function than renal healthy non-FD subjects (background population). The rate of renal function loss with age was independent of gender and predicted by high UACR. We suggest cautious interpretation of non-age-adjusted FD renal data.

Identification of eight novel SDHB, SDHC, SDHD germline variants in Danish pheochromocytoma/paraganglioma patients.

BACKGROUND: Germline mutations in the succinate dehydrogenase complex genes SDHB, SDHC, and SDHD predispose to pheochromocytomas and paragangliomas. Here, we examine the SDHB, SDHC, and SDHD mutation spectrum in the Danish population by screening of 143 Danish pheochromocytoma and paraganglioma patients. METHODS: Mutational screening was performed by Sanger sequencing or next-generation sequencing. The frequencies of variants of unknown clinical significance, e.g. intronic, missense, and synonymous variants, were determined using the Exome Aggregation Consortium database, while the significance of missense mutations was predicted by in silico and loss of heterozygosity analysis when possible. RESULTS: We report 18 germline variants; nine in SDHB, six in SDHC, and three in SDHD. Of these 18 variants, eight are novel. We classify 12 variants as likely pathogenic/pathogenic, one as likely benign, and five as variants of unknown clinical significance. CONCLUSIONS: Identifying and classifying SDHB, SDHC, and SDHD variants present in the Danish population will augment the growing knowledge on variants in these genes and may support future clinical risk assessments.

Exploring the experiences of people with hypo- and hyperthyroidism.

Thyroid diseases evoke a complex range of psychological and physical symptoms. The psychosocial aspects of living with diseases causing hypo- or hyperthyroidism are poorly understood. In this article, we report the findings of a qualitative interview study in which we explored the lived experiences of 16 people with hypo- or hyperthyroidism. We purposefully selected participants from Danish outpatient clinics according to their diagnosis (Hashimoto's thyroiditis or Graves' disease with or without orbitopathy), age (18 to 65 years), and duration of treatment (more than 6 months). We used interpretative phenomenological analysis (IPA) as a theoretical frame and analytical approach and identified three superordinate themes: losing control over mental and physical states, ambiguous signs of disease, and negotiating sickness. We discuss the findings in the context of the recent literature on chronic illness and argue that these themes play an important role in the conceptualization and management of thyroid diseases.

Epidemiology and diagnostic trends of congenital adrenal hyperplasia in Denmark: a retrospective, population-based study.

Background: The prevalence of newborns with congenital adrenal hyperplasia (CAH) detected by neonatal screening is well-described, but data including patients diagnosed later in life are extremely limited. This study aimed to describe diagnostic trends for all patients with CAH in Denmark. Methods: A nationwide population-based registry study including medical record review. Findings: We identified 462 patients (290 females) with any form of CAH. The prevalence of CAH combined was 15.1 (95% confidence interval [CI]: 12.3-16.1) and 9.0 (CI: 7.6-10.4) per 100,000 newborn females and males. There was a prevalence of salt-wasting (SW), simple-virilizing (SV), and non-classic (NC) CAH due to 21-hydroxylase deficiency of: SW-CAH: 6.4 (CI: 5.3-7.6) and 5.6 (CI: 4.6-6.8); SV-CAH: 2.0 (CI: 1.4-2.8) and 1.6 (CI: 1.0-2.7); and NC-CAH: 5.5 (CI: 4.4-6.9) and 2.5 (CI: 1.7-3.7) per 100,000 newborn females and males, respectively. Diagnosis of NC-CAH increased significantly during the course of the study. There was a female preponderance for SV-CAH (ratio: 1.8) and NC-CAH (ratio: 3.2). Median age at diagnosis, females and males respectively: SW-CAH: 4 (interquartile range [IQR]: 0-11) and 14 (IQR: 8-24) days, SV-CAH: 3.1 (IQR: 1.2-6.6) and 4.8 (IQR: 3.2-6.9) years, and NC-CAH: 15.5 (IQR: 7.9-22.5) and 9.4 (IQR: 7.2-23.2) years. Interpretation: The combined prevalence of CAH was 15.1 and 9.0 per 100,000 newborn females and males, respectively. The female preponderance was primarily due to diagnosis of more females than males with NC-CAH. Funding: International Fund of Congenital Adrenal Hyperplasia, Health Research Fund of Central Denmark Region, Aase and Einar Danielsen Fund, and "Fonden til Lægevidenskabens Fremme".

Diagnostic dilemma: a young woman with Fabry disease symptoms, no family history, and a "sequencing cryptic" α-galactosidase a large deletion.

Fabry disease, an X-linked lysosomal storage disorder, results from the deficient activity of α-galactosidase A (α-Gal A). In affected males, the clinical diagnosis is confirmed by the markedly decreased α-Gal A activity. However, in female heterozygotes, the α-Gal A activity can range from low to normal due to random X-chromosomal inactivation, and diagnostic confirmation requires identification of the family's α-Gal A gene mutation. In a young female who had occasional acroparesthesias, corneal opacities, and 15 to 50% of the lower limit of normal leukocyte α-Gal A activity, α-Gal A sequencing in two expert laboratories did not identify a confirmatory mutation, presenting a diagnostic dilemma. A renal biopsy proved diagnostic and renewed efforts to detect an α-Gal A mutation. Subsequent gene dosage analyses identified a large α-Gal A deletion confirming her heterozygosity, and she was started on enzyme replacement therapy. Thus, gene dosage analyses can detect large deletions (>50bp) in suspect heterozygotes for X-linked and autosomal dominant diseases that are "sequencing cryptic," resolving molecular diagnostic dilemmas.

Autonomic skin responses in females with Fabry disease.

Fabry disease is a genetic lysosomal disorder with dysfunction of the lysosomal enzyme alpha-galactosidase A causing accumulation of glycolipids in multiple organs including the nervous system and with neuropathy as a prominent manifestation. Neurological symptoms include pain and autonomic dysfunction. This study examined peripheral autonomic nerve function in 19 female patients with Fabry disease and 19 sex and age-matched controls by measuring (1) sweat production following acetylcholine challenge; (2) the sympathetically mediated vasoconstrictor responses to inspiratory gasp, stress, and the cold pressor test; and (3) cutaneous blood flow following capsaicin. The vasoconstrictor response to inspiratory gasp was increased in Fabry patients compared to controls (p = 0.03), while the response to cold and mental stress did not change. Female patients with Fabry disease had a reduced sweat response to iontophoresis of acetylcholine (p = 0.04) and a smaller capsaicin-induced flare compared to controls. These findings suggest that female patients both have an impaired C-fiber function and local abnormalities in blood vessels and sweat glands.

Enzyme Replacement Therapy During Pregnancy in Fabry Patients : Review of Published Cases of Live Births and a New Case of a Severely Affected Female with Fabry Disease and Pre-eclampsia Complicating Pregnancy.

Fabry disease (FD) is an X-linked, lysosomal storage disease. Mutations in the gene coding for alpha-galactosidase A lead to globotriaosylceramide (Gb-3) accumulation in lysosomes and in placenta and umbilical cord. Impact of FD and treatment with enzyme replacement (ERT) on foetal development is undisclosed.A 38-year-old primigravida with FD (G85N) is reported. She has 50% reduced alpha-galactosidase A activity and elevated plasma and urine-Gb-3. She was severely affected with ischaemic stroke at age 23, hypertension, albuminuria and moderately reduced renal function. ERT was initiated at age 23 years in 2001 and continued during spontaneous pregnancy at age 38. In third trimester she developed moderate-to-severe pre-eclampsia, successfully managed by methyldopa. Chorion villus sampling revealed a male foetus without the maternal gene mutation. Planned Caesarean section was performed without complications at gestational age week 38 + 6, delivering a healthy boy. Histopathological placental examination showed no sign of Gb-3 accumulation. Literature survey disclosed a total of 12 cases, 8 were treated with ERT during pregnancy and 5 infants inherited the family mutation. All outcomes were successful. In the six cases with available placental histopathological examination, Gb-3 accumulation was only seen on the foetal side if the foetus had the inherited mutation.In conclusion, the present case, describing the first data from a severely affected FD patient receiving ERT during pregnancy complicated by pre-eclampsia, together with all other published cases, has emphasized that ERT is safe during pregnancy and resulting in successful foetal outcome; despite this, ERT is by the health authorities advised against during pregnancy.

Affective symptoms and cognitive functions in the acute phase of Graves' thyrotoxicosis.

In the acute phase of Graves' thyrotoxicosis patients often have subjective cognitive complaints. Continuing controversy exists about the nature of these symptoms and whether they persist after treatment. This prospective study included 31 consecutively referred, newly diagnosed, and untreated patients with Graves' thyrotoxicosis. A control group of 34 individuals matched for age, education and premorbid intelligence was also included. At baseline all patients and control subjects were examined with psychiatric rating scales and a comprehensive neuropsychological battery. The effect of treatment on affective symptomatology was examined in the patient group after reaching euthyroidism and 1 year after treatment initiation. At initial examination patients had significantly higher scores on psychiatric rating scales as compared with controls, and the majority reported memory and concentration problems. No significant differences between the patient and the control group on neuropsychological test performances were found. Thyroid levels did not correlate with the neuropsychological test performances or psychiatric ratings. After reaching euthyroidism the level of affective symptoms (including reports of cognitive deficits) had decreased significantly, with further normalisation 1-year after treatment initiation. In conclusion, patients had subjective reports of cognitive deficits in the toxic phase of Graves' thyrotoxicosis but comprehensive neuropsychological testing revealed no cognitive impairment. Reports of cognitive dysfunction may reflect affective and somatic manifestations of thyrotoxicosis and in most patients these symptoms disappear after treatment of Graves' thyrotoxicosis.

The impact of severe hypoglycemia and impaired awareness of hypoglycemia on relatives of patients with type 1 diabetes.

OBJECTIVE: Severe hypoglycemia is a major problem for patients with type 1 diabetes and their relatives. The aim of this study was to compare patients' and relatives' assessments of rates of severe hypoglycemia and state of awareness and to explore the influence on involvement and concern of relatives. RESEARCH DESIGN AND METHODS: A cross-sectional paired questionnaire survey on hypoglycemia and the state of awareness was used in our study comprising 284 unselected adult patients with type 1 diabetes and their closest cohabitant. The cohabitant questionnaires also addressed involvement and concern. RESULTS: The agreement between assessments of rates of severe hypoglycemia and state of awareness made by patients and cohabitants was weak (kappa 0.404 and 0.442, respectively; P < 0.001). Cohabitants recalled more episodes of severe hypoglycemia than patients (2.7 vs. 1.6 episodes/patient-year; P < 0.001). Degree of involvement was positively related to the rate of severe hypoglycemia (P = 0.002) and negatively related to the state of awareness (P = 0.007) but not to level of HbA(1c), duration of diabetes, or presence of late complications, except for peripheral neuropathy (P = 0.01). CONCLUSIONS: Cohabitants of patients with type 1 diabetes recall significantly more episodes of severe hypoglycemia than the patients. The rate of severe hypoglycemia and state of hypoglycemic awareness are the principal determinants of degree of cohabitants' involvement in their partners' disease.

Familial isolated primary pigmented nodular adrenocortical disease associated with a novel low penetrance PRKAR1A gene splice site mutation.

BACKGROUND/AIMS: Primary pigmented nodular adrenocortical disease (PPNAD) is associated with inactivating germline protein kinase A regulatory subunit type 1-alpha (PRKAR1A) mutations and loss of heterozygosity at the 17q22-24 locus in approximately 50% patients. PRKAR1A mutations are observed in both isolated PPNAD (iPPNAD) and Carney complex (CNC). Most mutations result in a functionally null-allele and exhibit high penetrance. We genotyped members of an extended family for a novel PRKAR1A mutation and undertook detailed phenotyping for CNC in the affected individuals. METHODS: A 10.5-year-old male was diagnosed with PPNAD; the patient's mother also had iPPNAD. A 13-year-old sibling and 7 other relatives (mean age 58.2, range 29.1-80.2 years) were referred for PRKAR1A mutation analysis. RESULTS: DNA analysis of the index case and parent revealed a novel germline heterozygous PRKAR1A mutation at the +1 position of the acceptor site of intron 3 [c.349 G>T]. The same heterozygous splice site mutation was present in the sibling with no PPNAD or CNC manifestations and 2 other individuals aged 54.9 and 57.1 years who had subclinical Cushing's syndrome but no features of CNC. CONCLUSION: We conclude that c.349 G>T, a novel splice site germline PRKAR1A defect, has low penetrance resulting in incomplete clinical expression in this kindred.

Distribution of alpha-galactosidase A in normal human kidney and renal accumulation and distribution of recombinant alpha-galactosidase A in Fabry mice.

Deficiency of lysosomal alpha-galactosidase A (alpha-Gal A) in Fabry disease results in cellular accumulation of globotriaosylceramide (Gl3), often leading to end-stage renal failure. Gl3 accumulates in endothelial, glomerular, and tubular cells. Replacement therapy with recombinant alpha-Gal A to some extent reduces cellular accumulation of Gl3 in the kidney. This study shows high lysosomal expression of alpha-Gal A in all tubular segments and interstitial cells of normal human kidney. However, glomeruli and endothelial cells did not express the enzyme to any significant extent. Recombinant enzyme was taken up by rat yolk sac cells in a receptor-associated protein-inhibitive manner, and surface plasmon resonance experiments revealed binding to megalin, indicating a possible mechanism for uptake of alpha-Gal A in the tubular cells. After infusion into experimental animals or patients, alpha-Gal A was recovered in the urine, indicating glomerular filtration. Recombinant alpha-Gal A was also found in kidneys of normal and alpha-Gal A knockout mice by Western blotting and localized to endosomes and lysosomes in proximal tubules, interstitial cells, and glomerular podocytes by immunocytochemistry and autoradiography but not in vascular endothelial cells. In conclusion, intravenously administered enzyme is taken up by interstitial cells, is to some extent filtered in glomeruli, and is taken up by podocytes and reabsorbed by receptor-mediated endocytosis in proximal tubule cells, directly indicating a potential beneficial effect of enzyme replacement therapy for these cells.

Small-fibre neuropathy in female Fabry patients: reduced allodynia and skin blood flow after topical capsaicin.

Fabry disease is a rare X-linked lysosomal storage disorder. The mutations result in a deficiency of the lysosomal enzyme alpha-galactosidase A causing accumulation of glycosphingolipids in the vascular endothelial cells and many other tissues. Given the X-linked inheritance, male patients are severely affected. Recently, attention has been drawn to female patients whether they also show signs of nerve involvement. An early sign of the disease is painful small-fibre neuropathy. The aim of this study was to evaluate a small-fibre dysfunction in female Fabry patients by using capsaicin applied topically. The response to capsaicin was evaluated by laser Doppler imaging. We found that the female Fabry patients had a significantly smaller increase in blood flow (p = 0.0003) after capsaicin application. The area of static mechanical allodynia and dynamic mechanical hyperalgesia was also significantly smaller (p = 0.006) in female Fabry patients. This indicates that female Fabry patients have a significant loss of small-fibre function and demonstrates that it is possible to evaluate this by a non-invasive method.

Severe hypoglycaemia in 1076 adult patients with type 1 diabetes: influence of risk markers and selection.

BACKGROUND: Differences between studies in rates of severe hypoglycaemia in type 1 diabetic cohorts are common and poorly understood. The purpose of this study was to assess the frequency of severe hypoglycaemia in unselected patients treated in different secondary care centres and to evaluate the influence of risk markers, clinical setting and selection. METHODS: Cross-sectional Danish-British multicentre survey of 1076 consecutive adult patients with clinical type 1 diabetes who completed a detailed questionnaire on hypoglycaemia and related issues. Key variable was the self-reported rate of severe hypoglycaemia during the preceding year. RESULTS: The overall rate of severe hypoglycaemia in the preceding year was 1.3 episodes/patient-year and episodes were reported by 36.7% of subjects. The distribution was highly skewed with 5% of subjects accounting for 54% of all episodes. There were no significant differences between countries or centres. Reduced hypoglycaemia awareness, peripheral neuropathy and smoking were the only significant risk markers of severe hypoglycaemia in a stepwise multivariate analysis. In a subgroup selected to be similar to the Diabetes Control and Complications Trial (DCCT) cohort, the rate of severe hypoglycaemia was 0.35 episodes/patient-year and only retinopathy was a significant risk marker together with state of awareness. CONCLUSION: Severe hypoglycaemia remains a significant clinical problem in type 1 diabetes. The rate of severe hypoglycaemia and the influence of risk markers are very sensitive to selection and differences in rates between centres or studies seem to disappear after correction for differences in clinical characteristics. Smoking is a novel overall risk marker of severe hypoglycaemia.