Jackson-Weiss and Crouzon syndromes are allelic with mutations in fibroblast growth factor receptor 2.

Jackson-Weiss syndrome is an autosomal dominant condition characterized by craniosynostosis, foot anomalies and great phenotypic variability. Recently mutations in fibroblast growth factor receptor 2 (FGFR2) have been found in patients with another craniosynostotic syndrome, Crouzon syndrome. FGFR2 is a member of the tyrosine kinase receptor superfamily, having a high affinity for peptides that signal the transduction pathways for mitogenesis, cellular differentiation and embryogenesis. We now report an FGFR2 mutation in the conserved region of the immunoglobulin IIIc domain in the Jackson-Weiss syndrome family in which the syndrome was originally described. In addition, in four of 12 Crouzon syndrome cases, we identified two new mutations and found two previously described mutations in the same region.

Communicating hydrocephalus, basilar invagination, and other neurologic features in osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is anecdotally associated with macrocephaly, hydrocephalus, basilar invagination, and cerebral atrophy, but the frequency and the spectrum of neurologic features of this condition are poorly defined. We report our experience with 76 patients with OI seen at NIH. Neuroimaging studies demonstrated sulcal prominence and ventriculomegaly consistent with communicating hydrocephalus in 17 patients. Eight individuals with severe OI types displayed basilar invagination, causing brainstem compression in three patients. Head circumference growth showed abnormal kinetics with percentile crossing after fontanelle closure in 13 patients, and absolute macrocephaly was present in 11 patients. Additional neurologic complications included skull fracture (10 individuals); seizure disorders (five); transient, unexplained long tract signs (three); and spinal compression and pontine, cervical, and thoracic syringohydromyelia (one patient each). The clinically important neurologic complications appear to be brainstem compression from basilar invagination, skull fracture, and seizure disorders. Neurologic evaluation should be part of a team approach in the management of patients with severe OI types.

Cognitive and behavioral profile of the oculocerebrorenal syndrome of Lowe.

BACKGROUND: The oculocerebrorenal syndrome of Lowe (OCRL) is an X-linked disorder characterized by congenital cataracts, cognitive impairment, and renal tubular dysfunction. Significant behavioral difficulties have been reported, but no formal study of intelligence or behavior has been described. METHODS: We surveyed IQ and behavior using archival data and standardized instruments in 47 affected males. RESULTS: Mean IQ was in the moderate mental retardation range (40 < or = IQ < or = 54), with 25% of tested individuals in the normal range (IQ > or = 70). The OCRL population was comparable to a normative population with mental retardation in language, communication, and socialization skills, but lower in independent living skills than means of either populations of individuals with mental retardation or visual impairment. Maladaptive behaviors, particularly stubbornness, temper tantrums, and stereotypic behaviors, were very frequent (> 80%). CONCLUSIONS: The diagnosis of OCRL is compatible with normal intelligence. Maladaptive behaviors significantly interfere with adaptive functions. These behaviors appear to define a characteristic behavioral phenotype in OCRL.

Late occurrence of chronic immune-mediated axonal polyneuropathy following bone marrow transplant for juvenile-onset alpha-mannosidosis.

A 23-year-old woman with juvenile-onset alpha-mannosidosis developed an axonal polyneuropathy more than a year following successful unrelated donor (URD) BMT complicated by chronic graft-versus-host disease (GVHD). Progressive muscle weakness and paresthesias developed over at least 4 months, and made her nonambulatory. Nerve conduction and EMG studies demonstrated an axonal sensorimotor neuropathy. Cerebral spinal fluid (CSF) IgG was elevated with two peaks not identified in serum. Strength improved after a single course of plasma exchange and continued to improve over 12 months. The response to plasma exchange, elevated CSF IgG production, and evidence of a serum IgM peak suggest an immune-mediated mechanism. Chronic polyneuropathies following BMT are rare and are usually temporally related to GVHD or infection. This patient's disease was unusual because of its late occurrence and chronic onset in the face of resolved GVHD and in the absence of infection.

Fetal oculocerebrorenal syndrome of Lowe associated with elevated maternal serum and amniotic fluid alpha-fetoprotein levels.

OBJECTIVE: To report an association between fetal oculocerebrorenal syndrome of Lowe and elevations in maternal serum alpha-fetoprotein (MSAFP) and amniotic fluid alpha-fetoprotein (AFAFP). METHODS: Case 1 was identified during routine MSAFP screening. Cases 2-5 were identified through review of a data base of individuals with oculocerebrorenal syndrome enrolled at the National Institutes of Health. To estimate the frequency of this association, only those whose mothers would have been in the early second trimester from February 1987 to August 1993 were enumerated. The MSAFP was assumed to be normal unless explicitly reported or unless information outside the data base confirmed that MSAFP was not determined. RESULTS: An elevated MSAFP (2.5 multiples of the median [MoM] or greater) was detected in five of 20 pregnancies with a fetus affected by oculocerebrorenal syndrome. Maternal serum alpha-fetoprotein was greater than 5.0 MoM in three pregnancies undergoing amniocentesis, and all had an elevated AFAFP without significant acetylcholinesterase activity. No abnormalities were found by ultrasound, and there was no other cause of elevated AFP identified postnatally. Family history was positive in three of the five cases. The mothers were carriers in four of the five cases, whereas the fifth case appeared to be a spontaneous mutation. CONCLUSIONS: Elevated MSAFP and AFAFP appear to occur at a higher than expected frequency in pregnancies carrying an oculocerebrorenal syndrome fetus. The mechanism of elevation of AFP may be related to fetal renal tubular dysfunction. A directed interview, focusing on a maternal family history of male relatives with unexplained mental retardation, early institutionalization, or congenital rubella, is appropriate with unexplained MSAFP elevations and, particularly, with unexplained AFAFP elevations without acetylcholinesterase activity.

Assessment of adrenoleukodystrophy lesions by high field MRS in non-sedated pediatric patients.

BACKGROUND: Early detection of white matter lesions in childhood-onset cerebral adrenoleukodystrophy (ALD) is important as hematopoietic cell transplantation (HCT), currently the only effective treatment, is beneficial only if performed early in the disease course. OBJECTIVE: To establish reliable biochemical markers of cerebral disease progression in patients with ALD to aid in treatment planning. METHODS: The authors used proton magnetic resonance spectroscopy (MRS) in combination with LCModel analysis to quantify brain metabolites in small volumes (3 to 16 mL) in the occipital and frontal white matter and the splenium of the corpus callosum of 17 unsedated patients and 26 healthy volunteers (adult n = 21, age-matched n = 5) at 4 tesla. RESULTS: Absolute concentrations of 12 metabolites were reliably determined, seven of which were established as markers of lesion development. Among these, creatine and choline containing compounds were the weakest markers while N-acetylaspartate, glutamine, and lipids + lactate were the strongest. The large extent of changes in the markers enabled detection of early neurochemical changes in lesion formation prior to detection of abnormalities by conventional MRI. Concentrations of a number of metabolites were also significantly different between normal appearing white matter of patients and controls indicating biochemical alterations in the absence of cerebral disease. Neurochemical improvements following HCT were measured in six patients. CONCLUSIONS: The progression of adrenoleukodystrophy, as well as effectiveness of its treatment, can be assessed with high precision using high field 1H magnetic resonance spectroscopy in individual patients without the need for sedation.

Neurologic profile in osteogenesis imperfecta.

The clinically important neurlogic complications in 76 patients with OI seen at the NIH included brainstem compression from basilar invagination, skull fracture, and seizure disorders. Neuroimaging studies demonstrated sulcal prominence and ventriculomegaly consistent with communicating hydrocephalus in 17 patients. Basilar invagination was found in 8 individuals, all with clinically severe OI, and caused brain-stem compression in 3 patients. Head circumference growth showed abnormal kinetics with percentile crossing after fontanelle closure in 13 patients and absolute macrocephaly was present in 11 patients. Neurologic evaluation should be part of a team approach in the management of patients with severe OI types. Continued study of the underlying pathophysiology of neurologic features in OI is warranted.

Identification and developmental expression of a novel low molecular weight neuronal intermediate filament protein expressed in Xenopus laevis.

Xenopus laevis is a valuable model system for the study of vertebrate neuroembryogenesis. However, very few well-characterized nervous system-specific molecular markers are available for studies in this organism. We screened a X. laevis adult brain cDNA library using a cDNA probe for mouse low molecular weight neurofilament protein (NF-L) in order to identify neuron-specific intermediate filament proteins. Clones for two distinct neuron-specific intermediate filament proteins were isolated and sequenced. One of these encoded for a Xenopus NF-L (XNF-L) and the other for a novel neuron-specific Xenopus intermediate filament protein (XNIF) that was present earlier and more abundantly than XNF-L during development. XNIF contained a central rod domain with multiple sequence features characteristic of IF proteins. The XNF-L was very similar to mouse NF-L, with a 77% sequence identity in the rod domain and the presence of a polyglutamic acid region in the tail domain, characteristic of type IV neurofilament proteins. In contrast, XNIF showed only 60% identity to mouse NF-L in the rod domain and lacked the glutamic acid-rich sequence in the tail domain. XNIF also had a very low (approximately 38%) sequence identity in the head and tail domains as compared to NF-L and other neurofilament proteins (45% identity to the head domain of alpha-internexin). In the adult frog, XNIF mRNA is detected by Northern blots only within the nervous system and by in situ hybridization histochemistry exclusively in neurons, particularly in the medullary reticular system and spinal cord. Antisera raised against the unique tail region of XNIF detected a single distinct 60 kDa band in Western blots of nervous system cytoskeletal preparations, and this XNIF immunoreactivity was concentrated in axons in the PNS and in small perikarya in the dorsal root ganglion. In contrast, NF-L immunoreactivity was principally in the large perikarya in the dorsal root ganglion. In development, XNIF mRNA appears more abundant than XNF-L mRNA in all premetamorphic stages examined. XNIF mRNA is first detectable at stage 24 (26 hr), whereas stable expression of XNF-L is at stage 35/36 (50 hr). XNIF immunoreactivity is detectable within the cement gland, within many neuronal cell bodies and axon tracts within the developing nervous system, and within all cellular layers of the developing retina. The availability of these two distinct neuron-specific intermediate filament proteins, with different temporal and spatial expression patterns, should provide new markers as well as targets for functional perturbation in the developing X. laevis nervous system.

Nonsense mutations in the OCRL-1 gene in patients with the oculocerebrorenal syndrome of Lowe.

A candidate gene, OCRL-1, for the oculocerebrorenal syndrome of Lowe (OCRL) has been identified via positional cloning strategies. We have now developed RT-PCR techniques which allow amplification of nearly all of the open reading frame from total RNA and have used the PCR products for mutational analysis. Single strand conformational polymorphism analysis detected aberrant migration in two unrelated patients, both of whom were shown to have the same nonsense mutation at base 2746 on direct sequencing. An additional patient was found to be missing a segment from his RNA that corresponds to an entire exon. The identification of mutations in the OCRL-1 gene provides strong genetic evidence for its being the gene involved in Lowe syndrome.

Clinical and laboratory findings in the oculocerebrorenal syndrome of Lowe, with special reference to growth and renal function.

BACKGROUND: The oculocerebrorenal syndrome of Lowe is an X-linked disorder whose clinical manifestations include congenital cataracts, mental retardation, and renal tubular dysfunction. We investigated growth, renal function, and serum chemistry values in patients with the oculocerebrorenal syndrome to determine the natural history of the disorder and its heterogeneity with respect to these characteristics. METHODS: Twenty-three patients with the oculocerebrorenal syndrome, ranging in age from 4 months to 31 years, were examined. Height was compared with bone age. Renal function was assessed by measurements of proteinuria, urinary volume, and fractional excretions of potassium, phosphate, carnitine, and amino acids. Creatinine clearance was determined as a measure of glomerular function. RESULTS: In the oculocerebrorenal syndrome, linear growth decreases after one year of age; bone age lies between chronologic age and height age. Renal dysfunction occurs in the first year of life, characterized by proteinuria (mean [+/- SD], 1.38 +/- 0.77 g of urinary protein per square meter of body-surface area per day; normal, less than or equal to 0.10), generalized aminoaciduria (mean, 686 +/- 505 mumol of urinary amino acid per kilogram of body weight per day; normal, 94 +/- 45), carnitine wasting (mean fractional excretion, 0.10 +/- 0.05; normal, 0.03 +/- 0.01), and phosphaturia progressing into the third decade. Urinary wasting of individual amino acids is milder than in cystinosis, and branched-chain amino acids are relatively spared. Reciprocal serum creatinine levels fall linearly with age, predicting renal failure in the fourth decade. Concentrations of the muscle enzymes creatine kinase, aspartate aminotransferase, and lactate dehydrogenase, as well as of total serum protein, serum alpha 2-globulin, and high-density lipoprotein cholesterol, are elevated. CONCLUSIONS: Renal glomerular deterioration is slowly progressive in the oculocerebrorenal syndrome. Renal tubular dysfunction begins early and persists; most patients require alkalinization therapy, and many benefit from supplemental potassium, phosphate, calcium, or carnitine. Serum enzyme elevations suggest muscle involvement in the oculocerebrorenal syndrome.

Myalgia and elevated creatine kinase activity associated with subcutaneous injections of diluent.

A 16-year-old boy with short stature and mild primary hypothyroidism received subcutaneous injections of either recombinant human growth hormone or placebo in diluent that contained glycerol and m-cresol as a preservative. While he was receiving the study drug, myalgia developed and serum creatine kinase values were elevated. Both resolved when injections were stopped and recurred when injections of diluent alone were given. The myalgia and elevated creatine kinase activity were apparently caused by a component of the diluent.

Localization of the 75-kDa inositol polyphosphate-5-phosphatase (INPP5B) to human chromosome band 1p34.

The 75-kDa (type II) inositol polyphosphate-5-phosphatase, originally described in platelets, is one of at least three known enzymes capable of dephosphorylating inositol-1,4,5-trisphosphate (IP3) to inositol-1,4-bisphosphate (IP2). To further characterize these enzymatic forms, we have mapped the gene (INPP5B) coding for the 75-kDa type II enzyme. Using a combination of human x rodent somatic cell hybrids and fluorescence in situ hybridization, we have determined that this gene maps to human chromosome band 1p34.

Muscle carnitine repletion by long-term carnitine supplementation in nephropathic cystinosis.

The renal tubular Fanconi syndrome of children with nephropathic cystinosis causes plasma and muscle carnitine depletion. L-Carnitine replacement therapy for up to 18 mo has previously been shown to normalize plasma but not muscle carnitine levels. We treated six cystinosis patients, aged 1 to 4 y, with a mean dosage of 92 mg L-carnitine/kg/d given every 6 h for an average of 62 mo. Despite fractional excretions of free carnitine ranging from 55 to 108%, plasma-free and total carnitine concentrations were maintained at or above normal levels. At the end of the carnitine replacement period, the six children had muscle-free carnitine values ranging from 16.0 to 28.0 nmol/mg noncollagen protein compared with values of 3.0 to 11.4 for cystinosis children not supplemented with carnitine [normal, 22.7 +/- 5.0 (SD) nmol/mg protein]. Total muscle carnitine values were also normalized by L-carnitine replacement. The monthly increase in total body creatinine production, a measure of muscle mass, was higher (p = 0.036) in children with normal plasma free carnitine concentrations (3.4 +/- 0.9 mg/d) than in children with low plasma free carnitine (2.3 +/- 0.7 mg/d). No serious side effects, such as severe diarrhea, were observed. We conclude that oral L-carnitine replacement can normalize muscle carnitine content in children with cystinosis.

Schwann cell proliferation and migration during paranodal demyelination.

This study examined Schwann cell behavior during paranodal demyelination induced by beta,beta'-iminodipropionitrile (IDPN). The stimuli for Schwann cell proliferation, extensively studied in vitro, are less well understood in vivo. Most in vivo systems previously used to examine Schwann cell proliferation in disease are dominated by loss of internodal myelin sheaths. As used in this study, IDPN administration produces neurofilamentous axonal swellings and paranodal demyelination, without segmental demyelination or fiber degeneration. We asked whether Schwann cells would proliferate following the restricted paranodal demyelination that accompanies the axonal swellings, and if so what the sources and distributions of new Schwann cells might be. IDPN was given as a single large dose (2 ml/kg) to 21-d-old rats. Neurofilamentous axonal swellings formed in the proximal regions of motor axons, reaching their greatest enlargement in the root exit zone 8 d after IDPN administration. These swellings subsequently migrated distally down the nerves at rates approaching 1 mm/d. The axonal enlargement was consistently associated with displacement of the myelin sheath attachment sites into internodal regions, and consequent paranodal demyelination. This stage was associated with perikaryal changes, including nucleolar enlargement, "girdling" of the perikaryon, and formation of attenuated stalks separating the perinuclear region from the external cytoplasmic collar. Schwann cells proliferated abundantly during this stage. Daughter Schwann cells migrated within the endoneurial space (outside the nerve fiber basal laminae) to overlie the demyelinated paranodes of swollen nerve fibers. In these regions, local proliferation of Schwann cells continued, resulting in large paranodal clusters of Schwann cells. As the axonal calibers subsequently returned to normal, the outermost myelin lamellae of the original internodes returned to their paranodal attachment sites and the supernumerary Schwann cells disappeared. Formation of short internodes, segmental demyelination, and nerve fiber loss were rare phenomena. These results indicate that paranodal demyelination is a sufficient stimulus to excite abundant Schwann cell proliferation; neither internodal demyelination nor myelin breakdown is a necessary stimulus for mitosis. The 3H-thymidine incorporation studies indicated that the sources of new Schwann cells included markedly increased division of the Schwann cells of unmyelinated fibers and, as they formed, supernumerary Schwann cells. In addition, there were rare examples of 3H-thymidine incorporation by Schwann cells associated with myelinated nerve fibers.(ABSTRACT TRUNCATED AT 400 WORDS)

Distal vacuolar myopathy in nephropathic cystinosis.

Nephropathic cystinosis is a lysosomal storage disorder leading to renal failure by age 10 years. Prolonged patient survival following renal transplantation has allowed the development of previously unknown long-term complications. Muscle involvement has been reported in a single posttransplant cystinosis patient, but the range of clinical, electrophysiologic, and histologic features has not been fully described. Thirteen of 54 post-renal-transplant patients that we examined developed weakness and wasting in the small hand muscles, with or without facial weakness and dysphagia. Tendon reflexes were preserved and sensory examinations were normal. Electrophysiologic studies in 11 affected patients showed normal nerve conduction velocities and preserved sensory action potentials. The voluntary motor units in the affected distal muscles had reduced amplitude and brief duration, confirmed with quantitative electromyography in 4 patients. Biopsy of the severely affected abductor digiti minimi or extensor carpi radialis brevis muscles in 2 patients revealed marked fiber size variability, prominent acid phosphatase-positive vacuoles, and absence of fiber type grouping or inflammatory cells. Crystals of cystine were detected in perimysial cells but not within the muscle cell vacuoles. The muscle cystine content of clinically affected muscles was markedly elevated. We conclude that a distal vacuolar myopathy is a common late complication of untreated nephropathic cystinosis. Although the cause is unclear, the general lysosomal defect in this disease may also affect the lysosomes within muscle fibers.