Clinical and molecular features in a cohort of Middle Eastern patients with epidermolysis bullosa.

BACKGROUND: Epidermolysis bullosa (EB) features skin and mucosal fragility due to pathogenic variants in genes encoding components of the cutaneous basement membrane. Based on the level of separation within the dermal-epidermal junction, EB is sub-classified into four major types including EB simplex (EBS), junctional EB (JEB), dystrophic EB (DEB), and Kindler EB (KEB) with 16 EB-associated genes reported to date. METHODS: We ascertained a cohort of 151 EB patients of various Middle Eastern ethnic backgrounds. RESULTS: The cohort was comprised of EBS (64%, 97/151), DEB (21%, 31/151), JEB (12%, 18/151), and KEB (3%, 5/151). KRT14 and KRT5 variants were most common among EBS patients with 43% (42/97) and 46% (45/97) of EBS patients carrying mutations in either of these two genes, respectively. Truncal involvement was more common in KRT14-associated EBS as compared to EBS due to KRT5 mutations (p < .05). Mutations in COL17A1 and laminin 332-encoding genes were identified in 55% (10/18) and 45% (8/18) of JEB patients. Scarring alopecia, caries, and EB nevi were most common among JEB patients carrying COL17A1 mutations as compared to laminin 332-associated JEB (p < .05). Abnormal nails were evident in most DEB and JEB patients while poikiloderma was exclusively observed in KEB (p < .001). CONCLUSIONS: EB patients of Middle Eastern origin were found to feature specific phenotype-genotype correlations of relevance to the diagnosis and genetic counseling of patients in this region.

Acral peeling in Nagashima type palmo-plantar keratosis patients reveals the role of serine protease inhibitor B 7 in keratinocyte adhesion.

Acral peeling skin syndrome (APSS) is a heterogenous group of genodermatoses, manifested by peeling of palmo-plantar skin and occasionally associated with erythema and epidermal thickening. A subset of APSS is caused by mutations in protease inhibitor encoding genes, resulting in unopposed protease activity and desmosomal degradation and/or mis-localization, leading to enhanced epidermal desquamation. We investigated two Arab-Muslim siblings with mild keratoderma and prominent APSS since infancy. Genetic analysis disclosed a homozygous mutation in SERPINB7, c.796C > T, which is the founder mutation in Nagashima type palmo-plantar keratosis (NPPK). Although not previously formally reported, APSS was found in other patients with NPPK. We hypothesized that loss of SERPINB7 function might contribute to the peeling phenotype through impairment of keratinocyte adhesion, similar to other protease inhibitor mutations that cause APSS. Mis-localization of desmosomal components was observed in a patient plantar biopsy compared with a biopsy from an age- and gender-matched healthy control. Silencing of SERPINB7 in normal human epidermal keratinocytes led to increased cell sheet fragmentation upon mechanical stress. Immunostaining showed reduced expression of desmoglein 1 and desmocollin 1. This study shows that in addition to stratum corneum perturbation, loss of SERPINB7 disrupts desmosomal components, which could lead to desquamation, manifested by skin peeling.

Spectrum of genes for inherited hearing loss in the Israeli Jewish population, including the novel human deafness gene ATOH1.

Mutations in more than 150 genes are responsible for inherited hearing loss, with thousands of different, severe causal alleles that vary among populations. The Israeli Jewish population includes communities of diverse geographic origins, revealing a wide range of deafness-associated variants and enabling clinical characterization of the associated phenotypes. Our goal was to identify the genetic causes of inherited hearing loss in this population, and to determine relationships among genotype, phenotype, and ethnicity. Genomic DNA samples from informative relatives of 88 multiplex families, all of self-identified Jewish ancestry, with either non-syndromic or syndromic hearing loss, were sequenced for known and candidate deafness genes using the HEar-Seq gene panel. The genetic causes of hearing loss were identified for 60% of the families. One gene was encountered for the first time in human hearing loss: ATOH1 (Atonal), a basic helix-loop-helix transcription factor responsible for autosomal dominant progressive hearing loss in a five-generation family. Our results show that genomic sequencing with a gene panel dedicated to hearing loss is effective for genetic diagnoses in a diverse population. Comprehensive sequencing enables well-informed genetic counseling and clinical management by medical geneticists, otolaryngologists, audiologists, and speech therapists and can be integrated into newborn screening for deafness.

Characterization of human disease phenotypes associated with mutations in TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR, and IFIH1.

Aicardi-Goutières syndrome is an inflammatory disease occurring due to mutations in any of TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR or IFIH1. We report on 374 patients from 299 families with mutations in these seven genes. Most patients conformed to one of two fairly stereotyped clinical profiles; either exhibiting an in utero disease-onset (74 patients; 22.8% of all patients where data were available), or a post-natal presentation, usually within the first year of life (223 patients; 68.6%), characterized by a sub-acute encephalopathy and a loss of previously acquired skills. Other clinically distinct phenotypes were also observed; particularly, bilateral striatal necrosis (13 patients; 3.6%) and non-syndromic spastic paraparesis (12 patients; 3.4%). We recorded 69 deaths (19.3% of patients with follow-up data). Of 285 patients for whom data were available, 210 (73.7%) were profoundly disabled, with no useful motor, speech and intellectual function. Chilblains, glaucoma, hypothyroidism, cardiomyopathy, intracerebral vasculitis, peripheral neuropathy, bowel inflammation and systemic lupus erythematosus were seen frequently enough to be confirmed as real associations with the Aicardi-Goutieres syndrome phenotype. We observed a robust relationship between mutations in all seven genes with increased type I interferon activity in cerebrospinal fluid and serum, and the increased expression of interferon-stimulated gene transcripts in peripheral blood. We recorded a positive correlation between the level of cerebrospinal fluid interferon activity assayed within one year of disease presentation and the degree of subsequent disability. Interferon-stimulated gene transcripts remained high in most patients, indicating an ongoing disease process. On the basis of substantial morbidity and mortality, our data highlight the urgent need to define coherent treatment strategies for the phenotypes associated with mutations in the Aicardi-Goutières syndrome-related genes. Our findings also make it clear that a window of therapeutic opportunity exists relevant to the majority of affected patients and indicate that the assessment of type I interferon activity might serve as a useful biomarker in future clinical trials.

Long-term outcome of loss-of-function mutations in thyrotropin receptor gene.

BACKGROUND: Loss-of-function mutations in the thyrotropin receptor (TSHR) gene lead to resistance to TSH (RTSH) presenting with either congenital hypothyroidism (CH) or subclinical hypothyroidism (SCH). Despite several reports of patients with TSHR mutations, data on the long-term outcome of this condition are limited, and no consensus exists on the need for hormone replacement therapy. The aim of the present study was to assess the long-term outcome in children and adolescents with RTSH due to TSHR mutations. METHODS: The TSHR gene was sequenced in 94 subjects (aged 3 days-21 years) with either nonautoimmune SCH or CH with RTSH. RESULTS: Twenty-seven subjects (29%) carried mutations in TSHR. Fifteen infants were identified by neonatal screening, and the other 79 patients were detected in the process of testing for various other conditions or because of family occurrence of thyroid test abnormalities. Six different mutations were identified: c.484C>G (p.P162A), c.202C>T (p.P68S), c.790C>T (p.P264S), c.269A>C (p.Q90P), c.1957C>G (p.L653V), and c.1347C>T (p.R450C). Twelve subjects were homozygous, three were compound heterozygous, and 12 were heterozygous. Mean serum TSH levels at diagnosis and at last visit were significantly higher in patients with TSHR mutations than in those without mutations (29.04 vs. 14.15, p=0.002; 31.73 vs. 6.19, p<0.0001, respectively). Homozygous patients had a more severe phenotype (TSH 53.6 vs. 9.24, p<0.0001). Mean serum free thyroxine (fT4) levels at the last visit were significantly lower than at the first visit in the homozygous individuals (p=0.05) for a follow-up period of as long as 11 years. Heterozygous subjects had only mild hyperthyrotropinemia with stable TSH levels. However, homozygous subjects showed a trend toward increased TSH and decreased fT4 with time. CONCLUSION: SCH in heterozygotes with TSHR mutations is a stable compensated condition with an appropriately adjusted set point for pituitary-thyroid feedback that does not require replacement therapy. However, homozygous subjects, with incompletely compensated SCH, show reduced fT4 levels over time and may require levothyroxine treatment. Replacement therapy should be considered on an individual basis, and long-term follow up is recommended.

Factors affecting the utilization of genetic counseling services among Israeli Arab women.

OBJECTIVES: To assess the factors associated with utilization of genetic counseling services among pregnant Israeli Arab women. METHODS: A case-control study was conducted among 414 pregnant Arab women who were referred by a family physician or a perinatologist to genetic counseling services between 2008 and 2011. Data was collected using interviews, with both groups 'users' and 'non-users' of genetic counseling, based on a structured questionnaire including demographic, socio-economic, medical and cultural variables. RESULTS: In multivariate analysis, factors affecting women's utilization of genetic counseling service were high income level (OR 3.44, 95%CI 1.8-6.5, p < 0.001), high service accessibility (OR 0.75, 95%CI 0.67-0.84, p = 0.001), more positive attitude toward genetic counseling (OR 0.43, 95%CI 0.27-0.67, p = 0.012) and lower religiosity level (OR 1.40, 95%CI 0.94-2.09, p = 0.04). However, when we examined the following variable: pregnant woman's age, woman's education, consanguinity and pregnancy' age, knowledge level and the perspective toward abortion, no significant differences were found between the users and non-users groups. CONCLUSIONS: The underutilization of genetic counseling services among pregnant Israeli Arab women was associated with the following: lower income level, attitude toward genetic counseling, accessibility to service and religiosity. Thus, it is advisable to expand genetic counseling service within this community. © 2014 John Wiley & Sons, Ltd.

A novel mutation in IGFALS, c.380T>C (p.L127P), associated with short stature, delayed puberty, osteopenia and hyperinsulinaemia in two siblings: insights into the roles of insulin growth factor-1 (IGF1).

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. DESIGN: Sixty-five children with ISS were enrolled in the study. Serum ALS levels were measured by ELISA, and IGFALS was sequenced. RESULTS: A 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 (38 ng/ml) and extremely low IGF1 and IGFBP3 (<25 and <500 ng/ml, respectively) indicated GH insensitivity. Both affected siblings had low or no ALS (43 and 0 mU/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.

Compliance for genetic screening in the Arab population in Israel.

BACKGROUND: 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. OBJECTIVES: To assess the compliance of Arab couples with regard to genetic screening tests, and the factors that affect their decisions. METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

Can auxology, IGF-I and IGFBP-3 measurements followed by MRI and genetic tests replace GH stimulation tests in the diagnosis of GH deficiency in children?

BACKGROUND/AIMS: 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. METHODS: Fifty-three children diagnosed with GHD by two different GHSTs. GH-1 gene was sequenced. RESULTS: 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. CONCLUSION: 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.

Genetic heterogeneity in two consanguineous families segregating early onset retinal degeneration: the pitfalls of homozygosity mapping.

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.

Four USH2A founder mutations underlie the majority of Usher syndrome type 2 cases among non-Ashkenazi Jews.

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.

Variable phenotypes in familial isolated growth hormone deficiency caused by a G6664A mutation in the GH-1 gene.

CONTEXT: 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). OBJECTIVES: 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. DESIGN AND PATIENTS: Sixty-six subjects from two core families were included. The G6664A mutation among family members was determined by restriction fragment length polymorphism. RESULTS: 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. CONCLUSIONS: 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.

Clinical and genetic characteristics of congenital hypothyroidism due to mutations in the thyroid peroxidase (TPO) gene in Israelis.

OBJECTIVES: 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. PATIENTS: Twenty-two patients from six core families with congenital hypothyroidism (CH) and IOD living in the same region. DESIGN AND MEASUREMENTS: 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). RESULTS: 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. CONCLUSIONS: 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.

Abetalipoproteinemia in Israel: evidence for a founder mutation in the Ashkenazi Jewish population and a contiguous gene deletion in an Arab patient.

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.