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PubMedDate not supplied

Hypophosphatemic rickets: easy to diagnose, difficult to treat.

Hypophosphatemic rickets (HR) has generated a lot of interest in recent times. There is need to recognize this disorder and differentiate it from the more common nutritional rickets because the therapy is different. It is also important to emphasize that a detailed clinical examination with pedigree analysis and easily available biochemical tests are adequate to establish the diagnosis in most cases. This report presents three families with hypophosphatemic rickets. Interestingly, many of these patients had a mixed picture of HR and nutritional rickets. Their important features are described with special emphasis on early initiation of treatment with oral phosphate and stringent monitoring of renal functions to prevent development of irreversible renal insufficiency.

Adolescent↗

PubMed1996

An Xp22.1-p22.2 YAC contig encompassing the disease loci for RS, KFSD, CLS, HYP and RP15: refined localization of RS.

To facilitate the positional cloning of the genes involved in retinoschisis (RS), keratosis follicularis spinulosa decalvans (KFSD), Coffin-Lowry syndrome (CLS), X-linked hypophosphatemic rickets (XLH, locus name HYP) and X-linked dominant cone-rod degeneration (locus name RP15), we have extended the molecular map of the Xp22 region. Screening of several YAC libraries allowed us to identify 156 YACs, 52 of which localize between markers DXS414 (P90) and DXS451 (kQST80H1). Analysis of their marker content facilitated the construction of a YAC contig from the region spanning (in this order): DXS414 - DXS987 - DXS207 - DXS1053 - DXS197 - DXS 43 - DXS1195 - DXS418 - DXS999 - PDHA1 - DXS7161 - DXS443 - DXS 7592 - DXS1229 - DXS365 - DXS7101 - DXS7593 - DXS1052 - DXS274 - DXS989 - DXS451. The region between DXS414 and DXS451 covers about 4.5-5 Mb. Two additional markers (DXS7593 and DXS7592) were placed in the region, thereby increasing the genetic resolution. Using the deduced marker order, the analysis of key recombinants in families segregating RS allowed us to refine the critical region for RS to 0.6 Mb, between DXS418 and DXS7161.

Abnormalities, Multiple↗

PubMed1983

Hereditary resistance to 1,25-dihydroxyvitamin D: defective function of receptors for 1,25-dihydroxyvitamin D in cells cultured from bone.

UNLABELLED: The syndrome of rickets, alopecia, hypocalcemia, and high circulating levels of 1,25-dihydroxyvitamin D (1,25-(OH)2D) apparently is caused by resistance of target tissues to 1,25-(OH)2D. To evaluate this, we cultured cells from explants of long bone of one patient with this syndrome and from a control without any preexisting disorder of mineral metabolism. The cultured cells showed morphological features of fibroblasts but contained alkaline phosphatase activity without detectable acid phosphatase activity, indicating an osteoblastic origin for some or all of the cultured cells. Receptors for 1,25-(OH)2D were assessed by three methods: high affinity uptake of hormone in nuclei of dispersed cells, high affinity binding in hypertonic extracts (herein termed cytosol) from cells, and sedimentation velocity of bound [3H]1,25-(OH)2D3 in extracts of cell nuclei. With cells cultured from bone of the normal control, receptors for 1,25-(OH)2D exhibited properties indistinguishable from those found with cultured skin fibroblasts. With cells cultured from bone of the patient with resistance to 1,25-(OH)2D, high affinity uptake of 1,25-(OH)2D into nuclei was unmeasurable, but high affinity binding of hormone with cytosol was normal; these abnormal findings also were indistinguishable from abnormal findings obtained with fibroblasts cultured from skin of that patient. IN CONCLUSION: 1) Cells cultured from explants of human bone showed morphological features of fibroblasts but retained a marker enzyme characteristic of osteoblasts. Significant admixture of osteoblast-like cells with fibroblasts was possible. 2) Cells cultured from bone of a patient with familial resistance to 1,25-(OH)2D exhibit a defect in vitamin D metabolism, indistinguishable from the defect observed with cells cultured from skin of the same patient.

Acid Phosphatase↗

PubMed1997

A second family with XLRH displays the mutation S244L in the CLCN5 gene.

Mutations in the CLCN5 gene, mapped in Xp11.22, have been recently reported to be associated with X-linked nephrolithiasis, X-linked recessive hypophosphataemic rickets and Dent's disease. We report a missense mutation in exon 6 of the CLCN5 gene. The mutation in this pedigree is S244L, the same mutation as has previously been described in an Italian family showing a similar pathology. However, in the family reported here, affected males have developed neither nephrolithiasis nor nephrocalcinosis. The question arises whether we are dealing with a milder phenotype or whether a more severe pathology will develop with ageing.

Adolescent↗

PubMed1987

Autosomal dominant hypophosphataemia with elevated serum 1,25 dihydroxyvitamin D and hypercalciuria.

A 14-year-old boy presented with the clinical and radiological features of rickets. Serum inorganic phosphate levels were constantly low, whereas serum calcium and parathyroid hormone levels were within the normal range. Laboratory investigation did not show any evidence for vitamin-D deficiency, chronic renal insufficiency, Fanconi syndrome, tubular acidosis, hepatic disease or intestinal malabsorption. A family study comprising 34 members over four generations revealed 10 other individuals to be affected and the mode of inheritance to be autosomal dominant. In addition to hypophosphataemia and normocalcaemia, the disease is characterized by elevated serum 1,25 dihydroxyvitamin D levels and hypercalciuria. This hereditary syndrome of renal hypophosphataemia differs from the common familial X-linked hypophosphataemia and the recently described autosomal recessive hypophosphataemic rickets with hypercalciuria by its dominant mode of inheritance; it differs from hypophosphataemic non-rachitic bone disease by the elevated serum 1,25 dihydroxyvitamin D levels and hypercalciuria.

Adolescent↗

PubMed1987

Neurological involvement in X-linked hypophosphataemic rickets.

X-linked hypophosphataemic rickets is a familial form of Vitamin D resistant rickets in which gross bony and ligamentous changes may occur. Two patients showing severe spinal disease with evidence of spinal cord compression requiring neurosurgical intervention are reported. The management of such lesions may be problematic as cord compression may be found at several levels at presentation, and further difficulties develop after neurosurgical treatment.

Female↗

PubMed1974

Clinical phenotypes in kidney transport disorders.

Approximately 20 inherited disorders of kidney transport occurring in man have so far been defined. Most of these diseases have characteristic clinical profiles. They can be divided into four groups: 1) the amino acid transport mutations which include the cystinurias, hyperdibasicaminoaciduria, Joseph syndrome, Hartnup disease, and the methionine malabsorption syndrome: 2) the sugar transport mutations characterized by glucose (renal glucosuria), and glucose-galactose malabsorption; 3) the electrolyte and water transport disorders, among which are familial hypophosphatemic rickets, vitamin D-dependent rickets, pseudohypoparathyroidism, proximal and distal renal tubular acidosis, and nephrogenic diabetes insipidus; and 4) the "mixed" kidney transport mutations such as the "Busby", Fanconi, Lowe, Luder-Sheldon syndromes, and glucoglycinuria.

Abnormalities, Multiple↗

PubMed1978

Chronic familial hyperphosphatasemia.

Two siblings displaying macrocrania and multiple skeletal deformities, as well as cardiomegaly, had high levels of serum alkaline phosphatase and markedly increased urinary hydroxyproline excretion. The radiological findings of chronic familial hyperphosphatasemia, which are typical of a rare bone-remodeling disease, are presented. Scintigraphy disclosed intense uptake of the radionuclide by the skeletons of both patients. This finding, considered to be related to abnormal collagen metabolism, can be used in the diagnosis and assessment of skeletal involvement in such patients.

Bone and Bones↗

PubMed1984

Mouse mutants as models in endocrine research.

Although Shire (1979) has listed some forty-eight mouse mutants of interest to the endocrinologist, this short review has concentrated upon eleven mutations which have resulted in a significant number of scientific publications over the last 4 or 5 years. The selection of references has had to be limited, but it should be possible easily to expand the list given in this review. Although the proximate cause of none of the eleven mutations has been identified with certainty, the abnormalities of function have included hormone deficiencies and receptor and post-receptor malfunctions. It is perhaps a reflexion on our society in the 1980s, that the bulk of research has concentrated on the obese mouse. However, we still do not know the initial cause of this syndrome. The major disadvantage of the mouse to the hormone assayist lies in the small blood volume and the extreme difficulty in taking serial blood samples over a short period of time. With increased sophistication of assay techniques this may prove less daunting, but is an area where a review of the literature reveals discrepancies between laboratories, and even between data generated by the same laboratory at different times. With regard to the hormone content of endocrine tissues, the way forward for peptide-secreting glands may be in the measurement of mRNA levels for particular hormones. Certainly the methods of recombinant-DNA technology will yield positive information upon the aetiology and expression of some of the syndromes considered above. Organ transplantation is an area in which mutant mice have proved useful, for example gonadal, pituitary and pancreatic tissue transplantation. The grafting of neural tissue in the hpg mouse has added a further dimension to this field of research. The great infrastructure of genetical research in mice has enabled us to breed mutant genes onto different genetic backgrounds. This area of research is one which deserves to expand. The techniques of in vitro fertilization, chimera formation and embryo transfer have been used, in part, in studies on mouse mutants, and should provide technical means for further investigating gene expression. The family of dwarf mutants are ideally suited for research into the expression of genes micro-injected into the fertilized egg (see Charlton & Cox, 1983). As new hormones are isolated and become available for study these mouse mutants may well be useful in delineating physiological functions for natural and pharmacological products.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2003

Diagnosing thyrotoxic periodic paralysis in the ED.

Thyrotoxic periodic paralysis (TPP) and sporadic periodic paralysis (SPP) are the most common causes of hypokalemic periodic paralysis (HPP) in EDs in Asia. Their neuromuscular presentations are almost indistinguishable. We conducted this study to identify clinical clues that can help EPs distinguish between TPP and SPP. Thirty-four patients presenting to the ED with HPP were enrolled during a 3-year period. They did not have known hyperthyroidism before the attack and no family history of paralysis. They all had low K(+) excretion rates. Vital signs and blood biochemistry, including acid-base and electrolytes, were measured. TPP was subsequently established by thyroid function tests. Twenty patients had TPP and 14 patients had SPP. There was no significant difference in age and sex distribution between them. Systolic (SBP) but not diastolic blood pressure (SBP 145 +/- 4 vs 128 +/- 4 mm Hg, P < 0.001) and heart rate (106 +/- 3 vs 73 +/- 3 beats/min, P < 0.001) were significantly higher in those experiencing TPP than SPP. Among the biochemical factors, only plasma phosphate concentration (2.2 +/- 0.2 vs 3.2 +/- 0.2 mg/dL, P < 0.001) was significantly lower in those experiencing TPP than SPP. Systolic hypertension, tachycardia, and hypophosphatemia are clinical clues favoring the diagnosis of TPP.

Adult↗

PubMed1992

[The clinical relevance of phosphorus and calcium in infant nutrition].

This paper is an introduction to the clinical part of the symposium and deals with the question of whether and under which circumstances the calcium and phosphorus content in baby formula can provoke pathological conditions. In a healthy baby, high or low mineral intake is efficiently compensated for by Ca-P homeostasis. Both nutritional calcium deficiency and calcium excess are the exception with modern baby feeding practices. However, P-deficiency states resulting in phosphopenic rickets might occur in premature babies and in children with familial hypophosphatemic rickets. These two conditions should be treated and prevented by an alimentary P-supplement. On the other hand, formula with a rich P-content might be a cause of the late form of neonatal hypocalcemia. Therefore, a relatively low-phosphate formula preparation, similar to human milk, is recommended for the first 2 weeks of life of full-term newborns, as well for infants with hyperphosphatemic renal failure.

Calcium↗

PubMed1977

Long-term therapy with 1alpha-hydroxyvitamin D3 in children with 'pseudo-deficiency' rickets.

This investigation confirms that 1alpha-hydroxyvitamin D3 (1alpha-OHD3) is a potent drug for the treatment of patients with pseudo-deficiency rickets (Balsan et al., 1975a; Reade et al., 1975; Prader et al., 1976). 1alpha-OHD3 corrects their intestinal malabsorption of calcium and phosphorus, normalizes their serum calcium and phosphate concentrations and promotes healing of skeletal lesions. This study also shows differences in the needs for 1alpha-OHD3 of children with PDR. Three factors appear to be of importance: familial sensitivity, severity of chronic secondary hyperparathyroidism, and periods of increased growth velocity. Tolerance to long-term 1alpha-OHD3 therapy, at doses varying from 0.5 to 2 microgram/d is excellent. Surveillance of patients should include regular measurements of 24 h urinary excretion of calcium, since hypercalciuria is the first signal of overdosage.

Adolescent↗

PubMed1990

[Oral evaluation in various pathological conditions in children].

The current knowledge concerning the study of dental cavities cannot account for all clinical aspects of some subjects' resistance to cavity formation. This work concerned, in a first stage, the study of dental anomalies (number, shape and structure), in different groups of children with common diseases. This study has enabled us to evaluate the caries index of the same groups of children. It concerns 13 children with somatotropin deficiency (including 36% of children without any caries), 18 children with chronic renal insufficiency (including 56% of children without any caries), 4 children with Down's syndrome (no caries), one female child with erythropoietic porphyria (no caries), one girl with Incontinentia pigmenti (no caries) and one girl with familial, hypophosphatemic vitamin-resistant rickets (no caries). The percentage of children without any caries is particularly high in the groups under study, in spite of a poor oral hygiene. It seems that such factors as the conditions of dental development, the structure and morphology of the teeth or its environment, are capable of having an effect on caries formation.

Adolescent↗

PubMed1973

Familial hypophosphatemic rickets: defective transport of inorganic phosphate by intestinal mucosa.

Uptake of inorganic phosphate is impared in intestinal mucosa from hemizygous males and heterozygous females with X-linked familial hypophosphatemic rickets. Considerable intrafamilial and interfamilial variation in uptake of inorganic phosphate is observed in affected patients. Uptake by normal mucosa is concentrative and energy-dependent, and is mediated by at least two systems with widely different affinities. These results lend direct support to the thesis that the primary metabolic disturbance in this disease results from impaired transport of inorganic phosphate in kidney and gut.

Biological Transport↗

PubMed1980

[Familial hypophosphoremic rickets: pathogenic considerations based on two cases (author's transl)].

Familial hypophosphoremic rickets, although exceptional, is a frequent form of presentation in communities where nutritional rachitism has been eradicated. Hypophosphoremia is the biochemical defect which led to an insuffieient osseous mineralization. The real pathogenic mechanism of the disease is still unknown. Two patients, mother and son, who presented anamnesic, biochemical and roentgenographic characteristics suggesting a familial hypophosphoremic rachitism are reported. Clinical, biochemical and roentgenologic data of a secondary reactive hyperparathyroidism were absent in both cases. The present knowledge on the metabolic pathway of vitamin D and its metabolites led us to consider that the basic pathogenic defect appears as a consequence of an intestinal malabsorption of phosphates due to an altered synthesis of 1,25-dihydroxycholecalciferol or its precursor 25-hydroxycholecalciferol.

Adult↗

PubMed1994

Nephrocalcinosis in X-linked hypophosphataemic rickets: its relationship to treatment, kidney function, and growth.

We studied 25 patients treated with oral phosphate and 1,25(OH)2 vitamin D for 0.5-15 y (mean, 7 y) to determine the incidence of nephrocalcinosis and its relationship to treatment, renal function, and growth. During the follow-up period, 3 hypercalcaemic and 13 random hypercalciuric episodes were documented. Creatinine clearances and urine concentration tests were normal in all patients. One patient's 24-h urine specimen indicated hypercalciuria. Kidney ultrasonography revealed nephrocalcinosis in 80% of the patients, but its severity was not significantly related to the dose of calcitriol or of phosphate, the duration of treatment, the age at which treatment was started, or growth. None of the 9 untreated affected family members had nephrocalcinosis. Longitudinal studies revealed that the greatest loss in height velocity occurred during the first 2 y of life. Our study shows that nephrocalcinosis is a common complication of phosphate and 1,25(OH)2D3 treatment, but it is not necessarily associated with impaired renal function. Although the treatment failed to prevent a decrease in height velocity during infancy, it effectively maintained height velocity after 2 y of age.

Adolescent↗

PubMed1977

Adult-onset vitamin D-resistant hypophosphatemic osteomalacia. A possible variant of vitamin D-resistant rickets.

A family of 133 members showing unusual manifestations of vitamin D-resistant hypophosphatemic osteomalacia was studied. The hypophosphatemic children did not have rickets or clinical femoral bowing: the hypophosphatemic young adults had minimum clinically evident femoral bowing; and the older adults (age forty and older) were progressively disabled by severe bowing. The disorder appears to be an X-linked dominant, with almost complete penetrance of the hypophosphatemic trait. The etiology of this disorder could not be determined.

Adolescent↗

PubMedDate not supplied

[Molecular aspects of familial hypophosphatemic rickets].

Familial hypophosphataemic rickets (XLH) is an X-linked dominant disorder resulting in hypophosphataemia, abnormal regulation of 25-hydroxy vitamin D metabolism, elevated activity of alkaline phosphatase, bone deformities and short stature. In 1995-97 the sequence of PEX gene responsible for the disease was established. The PEX gene spreads 24.3 kb and includes 22 small exons coding a protein belonging to a neutral endopeptidase family. Function of the protein is not known yet. Mutation analysis in patients from North America, Africa and Europe (including Poland) revealed the presence of many different types of the PEX gene mutations. Identified deletions, insertions and substitution are supposed to change the structure of the PEX protein. Active form of vitamin D3, 1-alpha-hydroxylase and phosphate supplementation are now the recommended treatment of XLH patients. Further research is necessary to understand the role of the PEX protein in the pathogenesis of hypophosphatamic rickets.

Alkaline Phosphatase↗