Continuous glucose monitoring in children with glycogen storage disease type I.

BACKGROUND/OBJECTIVES: Glycogen storage disease type I (GSD I) is an autosomal recessive metabolic disorder caused by defects in the glucose-6-phosphatase complex. Deficient activity in the glucose-6-phosphatase-α catalytic unit characterizes GSD Ia and defects in the glucose-6-phosphate transporter protein characterize GSD Ib. Type Ia involves the liver, kidney and intestine (and Ib also leukocytes), and the clinical manifestations are hepatomegaly, failure to thrive, severe fasting hypoglycemia within 3-4 h after a meal, hyperlactatemia, hyperuricemia and hyperlipidemia. The aim of the present study was to examine the safety and efficacy of a continuous subcutaneous glucose monitoring system to determine the magnitude and significance of hypoglycemia in GSD I and to evaluate the efficacy of the revised dietary treatment. SUBJECTS/METHODS: Sixteen children with GSD I were studied over a 72-h period. Continuous glucose monitoring (CGM) was repeated in all patients 3-6 months after the first monitoring to examine the effects of revised dietary instructions on glycemic control. RESULTS: All the patients completed the study without any major adverse events. Significant periods of asymptomatic hypoglycemia (below 4 mmol/l, 70 mg/dl) were noted. There was a close correlation between CGM sensor and capillary blood glucose values measured by a glucometer. CGM indicated a considerable reduction in duration of hypoglycemia, liver size and improvements in secondary metabolic derangements such as hyperlacticacidemia and hyperlipidemia. CONCLUSIONS: CGM could be applied in the clinical setting to help the physician to identify hypoglycemic events, and repeated CGM may serve as a safe and useful tool for the assessment of the long-term management of patients with GSD I.

An extremely rare case: osteosclerotic metaphyseal dysplasia.

OMD (osteosclerotic metaphyseal dysplasia) is a very rare sclerosing bone disorder, first described by G. Nishimura in two Japanese siblings in 1993 (6). We report the case of a 12-month-old male with hypotonia, developmental delay and sclerosis of the metaphyses and epiphyses of specific bones. This 36-week gestation boy was born to a 26 year old gravida 5 para 1 Turkish mother and a 27 year old nonconsanguineous father. Radiographic findings obtained during the hospital stay included bilateral symmetrical osteosclerosis of the metaphyseal portions of the long bones in the upper and lower extremities with osteopenic shafts. Narrow bands of metaphyseal osteosclerosis were detected in the short tubular bones of the hands and feet. Growing parts of bilateral scapula, iliac, pubic and ischial bones show sclerotic bands. In addition superior and inferior plates of vertebras, transverse processes of sacral vertebras, all visible epiphyses, carpal and tarsal bones also show sclerotic changes. The scalp was unaffected. Based on the clinical, radiographic, and laboratory findings, a diagnosis of OMD was made. We do not know any of the osteosclerotic bone disorder with changes including hypotonia, mental and motor developmental delay and metaphyseal sclerosis of the bones with a unique distribution except OMD. The syndrome is characterized by developmental delay of a progressive nature, hypotonia, elevated alkaline phosphatase, and late-onset spastic paraplegia 18 years ago. Our patient is the 4th case of OMD described in the literature share some clinical and radiological similarities with other three reported cases of osteosclerotic metaphyseal dysplasias.

SRD5A3-CDG: a patient with a novel mutation.

Congenital disorders of glycosylation (CDG) are genetic diseases with an extremely broad spectrum of clinical presentations due to defective glycosylation of glycoproteins and glycolipids. Some 45 CDG types have been reported since the first clinical description in 1980. Protein glycosylation disorders are defects in protein N- and/or O-glycosylation. Dolichol phosphate is the carrier of the N-glycan during their assembly first at the outside and subsequently at the inside of the endoplasmic reticulum (ER) membrane, and hence is a key molecule in protein glycosylation. Recently, defects have been identified in the last three steps of the dolichol phosphate biosynthesis: dolicholkinase deficiency (DK1-CDG), steroid 5alpha-reductase type 3 deficiency (SRD5A3-CDG), and dehydrodolichyl diphosphate synthase deficiency (DHDDS-CDG). We report on a patient with SRD5A3-CDG carrying a novel (homozygous) mutation. The diagnostic features of this novel inborn error of glycosylation are psychomotor retardation, nystagmus, visual impairment due to variable eye malformations, cerebellar abnormalities/ataxia, and often ichthyosiform skin lesions.

A novel mutation of the claudin 16 gene in familial hypomagnesemia with hypercalciuria and nephrocalcinosis mimicking rickets.

Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is caused by a mutation in the gene CLDN16, which encodes paracellin 1 (claudin-16), atight junction protein mediating paracellular transport which is expressed in the thick ascending loop of Henle and in the distal convoluted tubule, where reabsorption of magnesium occurs. We present a 4 years old Turkish female child with a chief complaint of hypocalcemic tetany. A diagnosis of FHHNC was confirmed by genetic testing for a mutation in claudin 16 gene. Claudin 16 gene revealed homozygosity for the p.K183E(AAA>GAA) C. 547A>G indicating the diagnosis of hypomagnesemia with hypercalciuria and nephrocalcinosis. To our knowledge, this is the first case of FHHNC reported in Turkish population diagnosed at molecular level.