[Show abstract][Hide abstract] ABSTRACT: Background
The acid-labile subunit (ALS) protein is crucial for maintaining the circulating IGF/IGFBP system. Inactivating mutations of IGFALS result in IGF1 deficiency associated with growth retardation. Although the first IGFALS mutation in humans was described in 2004, only 16 mutations have been reported since. Moreover, the phenotype of affected patients as a consequence of ALS deficiency is still highly variable. We assessed whether children with idiopathic short stature (ISS) harbour mutations in IGFALS and characterized affected patients' phenotype. DesignSixty-five children with ISS were enrolled in the study. Serum ALS levels were measured by ELISA, and IGFALS was sequenced. ResultsA novel homozygous mutation in IGFALS, c.380T>C (p.L127P), was identified in two siblings of a consanguineous family. The proband, a 17 75 -year-old male, was -1 9 SDS in height and -4 5 SDS in weight. Exaggerated stimulated GH (38ng/ml) and extremely low IGF1 and IGFBP3 (<25 and <500ng/ml, respectively) indicated GH insensitivity. Both affected siblings had low or no ALS (43 and 0mU/ml, respectively). They were also mildly small for gestational age, severely underweight and showed osteopenia, insulin insensitivity and delayed and slow puberty progression. Conclusions
Acid-labile subunit deficiency due to IGFALS mutations is a rare cause of growth retardation in children. The unique combination of features presented by the two affected siblings emphasizes the important role of IGF1 in bone formation, insulin regulation and the pubertal process, in addition to its crucial effect on growth. Long-term follow-up is indicated since the clinical outcome with respect to osteoporosis, diabetes mellitus and fertility has not been recognized.
Full-text · Article · Mar 2013 · Clinical Endocrinology
[Show abstract][Hide abstract] ABSTRACT: Genetic screening tests for cystic fibrosis (CF), fragile X (FRAX) and spinal muscular atrophy (SMA) have been offered to the entire Arab population of Israel in the last few years. Since 2008, screening for CF is provided free of charge, but for FRAX and SMA the screening is privately funded with partial coverage by complementary health insurance programs.
To assess the compliance of Arab couples with regard to genetic screening tests, and the factors that affect their decisions.
We analyzed compliance for genetic screening tests at the Emek Medical Center Genetic Institute, and in outreach clinics in four Arab villages. We enquired about the reasons individuals gave for deciding not to undergo testing. We also assessed the compliance of these individuals for the triple test (a screening test for Down syndrome).
Of the 167 individuals included in our study, 24 (14%) decided not to be tested at all. Of the 143 (86%) who decided to be tested, 109 were tested for CF only (65%) and 34 (20%) for SMA and FRAX (as well as CF). The compliance rate for the triple test was 87%. Technical reasons, mainly financial issues, were the most significant factor for not undergoing all three tests.
The compliance of the Arab community for genetic testing for SMA and FRAX is extremely low. We believe that this low utilization of screening is due to economic reasons, especiallywhen a complementary health plan has not been acquired, and largely reflects the perception that these tests are less important since they are privately funded.
No preview · Article · Sep 2012 · The Israel Medical Association journal: IMAJ
[Show abstract][Hide abstract] ABSTRACT: GH levels < 10 ng/ml in response to two different GH stimulation tests (GHSTs) are traditionally used to identify children with GH deficiency (GHD). Since GHSTs are imprecise, other diagnostic tools have been proposed. We assessed whether auxology, IGF-I and IGFBP-3 measurements followed by brain MRI and genetic analysis can replace the current diagnostic approach.
Fifty-three children diagnosed with GHD by two different GHSTs. GH-1 gene was sequenced.
At presentation, 17% of patients were with height above -1.5 SD and 28% above -2.0 SD; 50% had IGF-1 concentration above -1.5 SD and 58% above -2.0 SD; 59% had pituitary anomalies demonstrated by MRI. Fourteen patients harbored the heterozygous R183H mutation, one patient had the N47D mutation and one had a novel F25Y mutation in GH-1. Using cut-off levels of -1.5 SD for height, IGF-I and IGFBP-3 excluded the diagnosis of GHD in 17, 68 and 79% of the children, respectively; a cut-off of -2 SD excluded 28, 88 and 96%, respectively. Further brain MRI and genetic tests excluded 81-96% and 96-100%, respectively, of children currently diagnosed with GH.
Use of the tested approach, which avoids carrying out two GHSTs, would exclude most children currently diagnosed with GHD. Until better tools become available, we recommend identifying GHD in children by an integrated approach combining phenotype, auxological parameters, hormonal measurements and two separate GHSTs, with MRI and genetic tests to support the diagnosis.
[Show abstract][Hide abstract] ABSTRACT: Retinitis pigmentosa is the most common form of hereditary retinal degeneration, with a worldwide prevalence of 1 in 4,000. At least 28 genes and loci have been implicated in nonsyndromic autosomal recessive retinitis pigmentosa. Here we report two extended and highly consanguineous families segregating early onset retinitis pigmentosa. Despite the consanguinity in both families, we found allelic heterogeneity in one of them, in which affected individuals were compound heterozygotes for two different mutations of the CRB1 gene. In the second family we found evidence for locus heterogeneity. A novel homozygous mutation of RDH12 was found in only 14 of 17 affected individuals in this family. Our data indicate that in the other affected individuals the disease is caused by a different gene/s. These findings demonstrate that while homozygosity mapping is an efficient tool for identification of the underlying mutated genes in inbred families, both locus and allelic heterogeneity may occur even within the same consanguineous family. These observations should be taken into account, especially when studying common and heterogeneous recessive genetic conditions.
No preview · Article · Apr 2009 · American Journal of Medical Genetics Part A
[Show abstract][Hide abstract] ABSTRACT: Type 2 Usher syndrome (USH2) is a recessively inherited disorder, characterized by the combination of early onset, moderate-to-severe, sensorineural hearing loss, and vision impairment due to retinitis pigmentosa. From 74% to 90% of USH2 cases are caused by mutations of the USH2A gene. USH2A is composed of 72 exons, encoding for usherin, an extracellular matrix protein, which plays an important role in the development and maintenance of neurosensory cells in both retina and cochlea. To date, over 70 pathogenic mutations of USH2A have been reported in individuals of various ethnicities. Many of these mutations are rare private mutations segregating in single families. The aim of the current work was to investigate the genetic basis for USH2 among Jews of various origins. We found that four USH2A mutations (c.239-240insGTAC, c.1000C>T, c.2209C>T, and c.12067-2A>G) account for 64% of mutant alleles underlying USH2 in Jewish families of non-Ashkenazi descent. Considering the very large size of the USH2A gene and the high number of mutations detected in USH2 patients worldwide, our findings have significant implications for genetic counseling and carrier screening in various Jewish populations.
[Show abstract][Hide abstract] ABSTRACT: G to A transition at position 6,664 (G6664A) in human GH-1 results in the substitution of arginine by histidine at position 183 (R183H) of the GH molecule and causes familial isolated GH deficiency type II (IGHD II).
The objective of the study was to assess the phenotype-genotype correlation of subjects affected with IGHD II caused by a G6664A mutation in 34 affected members of two large families.
Sixty-six subjects from two core families were included. The G6664A mutation among family members was determined by restriction fragment length polymorphism.
Twenty-four of the 52 members from family 1 and 10 of 14 from family 2 carried the same G6664A mutation in a heterozygous state. The affected subjects in family 1 were significantly shorter [-2.6 vs. -0.1 sd score (SDS), P < 0.0001] and had significantly lower IGF-I serum levels (-1.9 vs. -0.5 SDS, P < 0.0001), compared with normal-genotype family members. The affected adults exhibited great variability in their stature, ranging from -4.5 to -1.0 (mean -2.8 SDS), with five members being of normal height (>-2 SDS). Twelve children were diagnosed with IGHD. Two affected children had normal peak GH levels, although one of these subsequently demonstrated GH insufficiency (6.5 and 3.7 ng/ml). The affected children from both families exhibited large variability in their height, growth velocity, delay in bone age (chronological age - bone age), age at diagnosis, peak GH response, and IGF-I levels.
These detailed phenotypic analyses show the variable expressivity of patients bearing a G6664A mutation, reflecting the spectrum of GH deficiency in affected patients, even within families, and the presence of additional genes modifying height determination. Our findings raise a new dilemma in the guidelines for the diagnosis of GH deficiency and the indications for GH therapy.
Full-text · Article · Nov 2007 · Journal of Clinical Endocrinology & Metabolism
[Show abstract][Hide abstract] ABSTRACT: Iodide organification defect (IOD) is characterized by a reduced ability of the thyroid gland to retain iodide and results in hypothyroidism. Mutations in the thyroid peroxidase (TPO) gene are a frequent cause of IOD. While TPO mutations have been identified in various populations, none have been reported in Israeli patients with IOD. The objectives of this study were to characterize the molecular basis of IOD in an Israeli Arab-Muslim population and to analyse the clinical, neurological and imaging data of patients with TPO mutations followed for up to 29 years.
Twenty-two patients from six core families with congenital hypothyroidism (CH) and IOD living in the same region.
All subjects underwent clinical, hormonal and imaging evaluation. The TPO gene was directly sequenced and the presence of specific mutations among family members was determined by restriction fragment length polymorphism (RFLP).
All patients had congenital and persistent primary hypothyroidism. The thyroid gland was demonstrated in all subjects by technetium (99mTc) scans. A positive perchlorate discharge test (mean 87%) was indicative of IOD. Enlargement of the thyroid gland was shown in 64% of our patients, mostly with multinodular appearance, and in some with retrosternal invasion. Neurological complications were observed in 13 patients (59%). Four subjects, who carry two different TPO mutations, had sensorineural deafness. Two previously described TPO gene mutations [G1567A (G493S) and C1708T (R540X)] and one novel TPO gene mutation [C965T (S292F)] were identified. The two previously described mutations were present in 90% of the subjects. Haplotyping suggested a distant common ancestry for each of these two mutations.
Three different TPO gene mutations were found to be responsible for IOD in a consanguineous Israeli population. The high rate of development of multinodular glands (MNGs) in our cohort of patients indicates the need for long-term follow-up of patients with TPO gene mutations.
No preview · Article · Jun 2007 · Clinical Endocrinology
[Show abstract][Hide abstract] ABSTRACT: Abetalipoproteinemia (ABL) is a rare autosomal recessive metabolic disorder, characterized by the absence of plasma apolipoprotein B-containing lipoproteins and very low levels of plasma triglycerides and cholesterol. ABL is caused by mutations of the MTP gene. We investigated the genetic basis for ABL in a cohort of Israeli families. In Ashkenazi Jewish patients we identified a conserved haplotype and a common MTP mutation, p.G865X, with a carrier frequency of 1:131 in this population. We also report the first case of ABL and additional abnormalities in a Muslim Arab patient, due to a homozygous contiguous gene deletion of approximately 481 kb, including MTP and eight other genes.
No preview · Article · May 2007 · Molecular Genetics and Metabolism