Cytogenomic characterization of 1q43q44 deletion associated with 4q32.1q35.2 duplication and phenotype correlation.

BACKGROUND: Microdeletion of 1q43q44 causes a syndrome characterized by intellectual disability (ID), speech delay, seizures, microcephaly (MIC), corpus callosum abnormalities (CCA) and characteristic facial features. Duplication of 4q is presented with minor to severe ID, MIC and facial dysmorphism. We aimed to verify the correlation between genotype/phenotype in a patient with 1q43q44 deletion associated with 4q32.1q35.2 duplication. CASE PRESENTATION: We report on a 3 year-old female patient with delayed motor and mental milestones, MIC and facial dysmorphism. She is a child of non-consanguineous parents and no similarly affected family members. CT brain showed abnormal gyral patterns, hypogenesis of corpus callosum and bilateral deep Sylvian fissure. Electroencephalogram showed frontotemporal epileptogenic focus. Her karyotype was revealed as 46,XX,add(1)(q44). Fluorescence in situ hybridization (FISH) using whole chromosome paint (WCP1) and subtelomere 1q revealed that the add segment was not derived from chromosome 1 and there was the deletion of subtelomere 1q. Multiple ligation probe amplification (MLPA) subtelomere kit revealed the deletion of 1q and duplication of 4q. Array CGH demonstrated the 6.5 Mb deletion of 1q and 31 Mb duplication of chromosome 4q. CONCLUSION: The phenotype of our patient mainly reflects the effects of haploinsufficiency of AKT3, HNRNPU, ZBTB18 genes associated with duplication of GLRA3, GMP6A, HAND2 genes. Patients presented with ID, seizures, MIC together with CCA are candidates for prediction of 1q43q44 microdeletion and cytogenomic analysis.

Genetic study of eight Egyptian patients with pycnodysostosis: identification of novel CTSK mutations and founder effect.

This is the first Egyptian study with detailed clinical and orodental evaluation of eight patients with pycnodysostosis and identification of four mutations in CTSK gene with two novel ones and a founder effect. INTRODUCTION: Pycnodysostosis is a rare autosomal recessive skeletal dysplasia due to mutations in the CTSK gene encoding for cathepsin K, a lysosomal cysteine protease. METHODS: We report on the clinical, orodental, radiological, and molecular findings of eight patients, from seven unrelated Egyptian families with pycnodysostosis. RESULTS: All patients were offspring of consanguineous parents and presented with the typical clinical picture of the disorder including short stature, delayed closure of fontanels, hypoplastic premaxilla, obtuse mandibular angle, and drum stick terminal phalanges with dysplastic nails. Their radiological findings showed increased bone density, acro-osteolysis, and open cranial sutures. Mutational analysis of CTSK gene revealed four distinct homozygous missense mutations including two novel ones, c.164A>C (p. K55T) and c.433G>A (p.V145M). The c.164A>C (p. K55T) mutation was recurrent in three unrelated patients who also shared similar haplotype, suggesting a founder effect. CONCLUSION: Our findings expand the mutational spectrum of CTSK gene and emphasize the importance of full clinical examination of all body systems including thorough orodental evaluation in patients with pycnodysostosis.

Hypermanganesemia with dystonia, polycythemia and cirrhosis in 10 patients: Six novel SLC30A10 mutations and further phenotype delineation.

Biallelic mutations in the SLC30A10 gene cause an inborn error of Mn metabolism characterized by hypermanganesemia, polycythemia, early-onset dystonia, and liver cirrhosis (HMDPC). To date, only 14 families from various ethnic groups have been reported. Here, we describe 10 patients from 7 unrelated Egyptian families with HMDPC. Markedly elevated blood Mn levels, the characteristic basal ganglia hyperintensity on T1-weighted images, and variable degrees of extrapyramidal manifestations with or without liver disease were cardinal features in all patients. Eight patients presented with striking early diseased onset (≤2 years). Unexpectedly, early hepatic involvement before the neurological regression was noted in 3 patients. Mutational analysis of SLC30A10 gene revealed 6 novel homozygous mutations (c.77T > C (p.Leu26Pro), c.90C > G (p.Tyr30*), c.119A > C (p.Asp40Ala), c.122_124delCCT (p.Ser41del), c.780_782delCAT (p.Iso260del) and c.957 + 1G > C). Treatment using 2,3 dimercaptosuccinic acid as a manganese chelating agent showed satisfactory results with improvement of biochemical markers, hepatic manifestations and relative amelioration of the neurological symptoms. Our findings present a large cohort of patients with HMDPC from same ethnic group. The majority of our patients showed severe and early presentation with clear phenotypic variability among sibship. Moreover, we extend the phenotypic and mutational spectrum and emphasize the importance of early diagnosis and treatment of this potentially fatal disorder.

PGAP3-related hyperphosphatasia with mental retardation syndrome: Report of 10 new patients and a homozygous founder mutation.

BACKGROUND: Hyperphosphatasia with mental retardation syndrome (HPMRS) is caused by recessive mutations in genes involved in the glycosylphosphatidylinsitol pathway, including PGAP3. MATERIALS AND METHODS: We describe 10 patients from 8 Egyptian families presenting with developmental delay, severe intellectual disability, distinct facial dysmorphism and increased alkaline phosphatase. Sanger sequencing of PGAP3 was performed. RESULTS: Eight patients had cleft palate, 4 had postnatal microcephaly and 5 had seizures. Neuro-imaging findings showed thin corpus callosum in 9 patients, mild ventriculomegaly in 3 patients and variable degrees of cerebellar vermis hypoplasia in 4 patients, a finding not previously reported in patients with HPMRS. Additional manifestations included double row teeth, hypogenitalism and congenital heart disease. Biallelic loss of function mutations in the PGAP3 gene were detected in all patients. Nine patients were homozygous for the c.402dupC (p.M135Hfs*28) mutation strongly suggesting a founder effect. On the other hand, 1 patient had a novel mutation, c.817_820delGACT (p.D273Sfs*37). CONCLUSION: This is the largest series of patients with HPMRS from same ethnic group. Our results reinforce the distinct clinical and facial features of PGAP3-related HPMRS which are the clue for targeted genetic testing. Moreover, we present additional unreported clinical and neuro-imaging findings and a novel mutation thus expanding the phenotypic and mutational spectrum of this rare disorder.

CO-OCCURRENCE OF PRIMARY MICROCEPHALY CAUSED BY A NOVEL HOMOZYGOUS ASPM MUTATION ALONG WITH X-LINKED ICHTHYOSIS IN THE SAME PATIENT.

Autosomal recessive primary microcephaly is a heterogeneous genetic disorder caused by genes that affect neurogenesis. This form of microcephaly has not been associated with other congenital anomalies. ASPM mutations have been identified as the major cause implicated in autosomal recessive primary microcephaly. X-linked recessive ichthyosis, is an inborn error of steroid sulfatase metabolism characterized by dark and adhesive scaly skin. Here, we examined an Egyptian boy presenting with microcephaly and simplified gyral pattern. Additionally, he had ichthyosis that goes with the X-linked type. Mutation analyses of the ASPM gene for autosomal recessive primary microcephaly and STS gene of X-linked recessive ichthyosis were conducted revealing a co-occurrence of a novel homozygous splice site mutation of ASPM gene (c.2936+1G>A) and a partial deletion of STS spanning from exon 7-10. We propose that the phenotype of our patient results from the combined effects of mutations in both ASPM and STS that account for the neurological signs and skin manifestations, respectively. The association of isolated X-linked recessive ichthyosis and autosomal recessive primary microcephaly has never been reported in the literature. Careful clinical and genetic assessment of patients with atypical clinical phenotypes is crucial for detecting such rare double mutations and thus proper genetic counseling.

Effect of dehydroepiandrosterone (DHEA) on memory and brain derived neurotrophic factor (BDNF) in a rat model of vascular dementia.

The effect of dehydroepiandrosterone (DHEA) on memory and cognition in experimental animals is well known, but its efficacy in clinical dementia is unproven. So, the aim of the present study was to investigate the effect of DHEA on learning and memory activities in a rat model of vascular dementia (VD). Forty-eight male rats that positively passed the holeboard memory test were chosen for the study before bilateral permanent occlusion of the common carotid artery. They were divided into four groups (n=12, each) as follows (i) untreated control, (ii) rats exposed to surgical permanent bilateral occlusion of the common carotid arteries (BCCAO) leading to chronic cerebral hypoperfusion, (iii) rats exposed to BCCAO then received DHEA (BCCAO + DHEA) and (i.v.) rats exposed to BCCAO then received donepezil (BCCAO + DON). Holeboard memory test was used to assess the time, latency, working memory and reference memory. Central level of acetylcholine, norepinephrine and dopamine in the hippocampus were measured. Furthermore, the expression of brain derived neurotrophic factor (BDNF) in the hippocampus was determined. Histopathological studies of the cerebral cortex and transmission electron microscope of the hippocampus were performed. BCCAO decreased the learning and memory activities in the holeboard memory. Also, it decreased the expression of BDNF as well as the central level of acetylcholine, noradrenaline and dopamine as compared to control rats. Treatment with DHEA and donepezil increased the working and reference memories, BDNF expression as well as the central acetylcholine in the hippocampus as compared to BCCAO rats. DHEA produced neuroprotective effects through increasing the expression of BDNF as well as increasing the central level of acetylcholine and catecholamines which are non-comparable to donepezil effects.

Holoprosencephaly spectrum among Egyptian patients: clinical and cytogenetic study.

We report 24 patients with holoprosencephaly (HPE) spectrum screened for Del 7q36 and subtelomere 13q. They were divided according to the type of HPE into: 6 alobar, 15 semilobar, 1 lobar and 2 middle interhemispheric variant (MIH). All patients presented with global developmental delay. Microcephaly was in 83.3% and midfacial developmental defects were in the form of; cyclopia, arrhinia and agnathia in 2 patients (8.3%), premaxillary agenesis in 2 patients (8.3%), cleft lip and palate in 7 patients (29.2%), hypotelorism in 8 patients (33.3%) and hypertelorism in 9 patients (37.5%). The neurological deficits were as follows: abnormal tone and spasticity were present in all of them with exceptional of a single patient with MIH who presented with hypotonia and was able to walk independently at the age of 3 years, athetoid and/or dystonic movements of limbs in 22 patients, seizures in twelve patients (50%) and abnormal EEG in 15 patients (62.5%). Poor temperature regulation was found in 50% of patients and diabetes insipidus was documented in 3 patients (12.5%). The MRI showed complete or partial fusion of basal ganglia and thalami in 21 patients (87.5%) and 19 patients (79.2%) respectively, fused mesencephalon in 8 patients (33.3%), incomplete separation of mesencephalon from diencephalon in 4 patients (16.7%), dorsal cyst in 10 patients (41.7%), abnormal gyral pattern anteriorly in 15 patients (62.5%), anterior located sylvian fissures in 22 patients (99.7%), complete or partial agenesis of the corpus callosum (ACC) in all patients and Dandy-Walker malformation (DWM) in three patients (12.5%). A small occipital cephalocele was detected clinically and radiological as atretic type in MIH patient. Karyotype analysis demonstrated 47, XY+13 in a patient with alobar holoprosencephaly, 46, XY,t(12;13) (q13q24.1;q14q33) in a semilobar case associated with DWM, 46, XY, del(13)(q34) in one semilobar case and three cases had del 7q36 using FISH technique in two semilobar cases and one lobar case. Conclusion: This study highlights the clinical spectrum in patients with HPE and report a case of HPE and DWM associated with t(12;13). Neuroimaging delineated the pathogenesis underlying developmental defects in HPE. Accurate molecular diagnosis is crucial for further understanding of the pathogenesis of HPE.

Identification of three novel ECEL1 mutations in three families with distal arthrogryposis type 5D.

Arthrogryposis refers to congenital contracture in at least two different body parts. When distal joints are primarily involved, the term distal arthrogryposis (DA) is used. The recognition of clinically distinct subtypes of DA has proven very useful in mapping the disease genes for this genetically heterogeneous condition. DA5D is characterized by ocular involvement usually in the form of ptosis and incomitant strabismus, but extraocular manifestations have also been reported. In a multiplex consanguineous family with DA5D, we combined autozygosity mapping and exome sequencing to identify a novel mutation in ECEL1. This was followed by targeted sequencing of this gene in another two extended consanguineous family with the same phenotype, which revealed two additional novel homozygous mutations. Our results support the recent identification of mutations in ECEL1 as a disease gene in DA5D and expand the clinical and allelic spectrum of this condition.

Ring chromosome 15: expanding the phenotype.

Ring chromosome 15 is a rare disorder, with less than 50 cases reported in the literature to date. We report the clinical and cytogenetic evaluation of a patient with ring chromosome 15. Diagnostic tests including echocardiography, abdominal ultrasound, brain computerized tomography (CT), magnetic resonance imaging (MRI) and electroencephalogram (EEG) were done. Clinical examination of the patient revealed the characteristic features of ring chromosome 15, such as growth retardation, hypertelorism, frontal bossing, a highly arched palate, small hands and feet and café-au-lait spots. In addition, the patient presented with a mild intellectual disability, a congenital atrial septal heart defect, and abnormal EEG records. We also report 2 novel findings, which to our knowledge; have not been reported before in ring chromosome 15 patients: large areas of hyperpigmentation on the front of both legs and feet and hypogenesis of the corpus callosum. Cytogenetic studies using both conventional G-banding and fluorescence in situ hybridization (FISH) with a Sub Tel 15q probe confirmed the diagnosis of ring chromosome 15.

Bartsocas-Papas syndrome with variable expressivity in an Egyptian family.

Bartsocas-Papas syndrome (BPS) is an autosomal recessively inherited sublethal popliteal pterygium condition characterized by intrauterine or neonatal death, severe popliteal webbing, oligosyndactyly, ankyloblepharon, orofacial clefts, intraoral filiform bands and genital anomalies. Internal organ involvement has seldom been identified. We report on a 3 years old female patient of healthy first cousin parents with BPS. She presented with orofacial clefting, severe popliteal webs, club feet, oligosyndactyly of the toes, hypogenitalism and normal hands and internal organs. Ankyloblepharon and filiform bands between the alveolar ridges were evident at birth. Pedigree analysis revealed a more severely affected female sib, who died a few minutes after birth with additional manifestations including near complete lip fusion without oral cleft, complete syndactyly in both hands and an omphalocele. Linkage was excluded to the IRF6 gene; a candidate gene implicated in the Van der Woude and popliteal pterygium syndromes, with overlapping features with BPS. To our knowledge, this is the 5th surviving patient with this syndrome in the literature. In this report, we also discuss the proposed pathogenetic mechanisms for BPS and compare our patients with similarly described cases as well as overlapping spectrum of other popliteal pterygium syndromes. Our findings provide further evidence of intrafamilial clinical heterogeneity in families with BPS.

Emanuel syndrome due to unusual segregation of paternal origin.

Emanuel syndrome is an inherited chromosomal abnormality resulting from 3:1 meiotic segregation from parental balanced translocation carrier t(11;22)(q23;q11), mostly of maternal origin. It is characterized by mental retardation, microcephaly, preauricular tag or sinus, ear anomalies, cleft or high arched palate, micrognathia, congenital heart diseases, kidney abnormalities, structural brain anomalies and genital anomalies in male. Here in, we describe a female patient with supernumerary der(22) syndrome (Emanuel syndrome) due to balanced translocation carrier father t(11;22) (q23;q11). She was mentally and physically disabled and had most of the craniofacial dysmorphism of this syndrome. Our patient had cleft palate, maldeveloped corpus callosum and hind brain with normal internal organs. Additionally, arachnodactyly, hyperextensibility of hand joints, abnormal deep palmar and finger creases, extra finger creases and bilateral talipus were evident and not previously described with this syndrome. Cytogenetic analysis and FISH documented that the patient had both translocation chromosomes plus an additional copy of der(22) with karyotyping: 47,XX,t(11; 22)(q23;q11),+der(22)t(11;22)(q23;q11). We postulated that this rare chromosomal complement can arise from; 2:2 segregation in the first meiotic division of the balanced translocation father followed by non-disjunction at meiosis II in the balanced spermatocyte.

Bladder exstrophy and extreme genital anomaly in a patient with pure terminal 1q deletion: expansion of phenotypic spectrum.

We describe a 5 2/12 years old male patient with a de novo deletion 1q43q44 of approximately 10.4 Mb in size. The boy presented with the classic features of chromosome 1q43q44 deletion syndrome including growth and psychomotor retardation, microcephaly, distinct facial features and various midline defects as agenesis of corpus callosum, cardiac and urogenital anomalies. Fronto-parietal simplified gyral pattern was an additional neuroimaging finding. The urogenital anomalies in our patient were remarkable in form of bladder exstrophy and severe hypogenitalism with a marked hypoplastic scrotum, small sized retractile testis and absent phallus. To the best of our knowledge, bladder exstrophy and absence phallus have not been previously reported in terminal deletion 1q43q44 syndrome. This report provides further evidence of phenotype-genotype correlation and expands the phenotypic spectrum of midline defects described with this syndrome.

Prenatal magnetic resonance imaging diagnosis of molar tooth sign at 17 to 18 weeks of gestation in two fetuses at risk for Joubert syndrome and related cerebellar disorders.

We report on the prenatal MRI diagnosis of Joubert syndrome and related cerebellar disorders (JSRD) in 2 unrelated fetuses at 17-18 weeks of gestation who were referred to us with history of siblings with JSRD and additional renal affection in the second case. Ultrasonography (US) showed non-specific cranial findings in both fetuses such as prominent cisterna magna and ventricular system as well as bilateral renal enlargement in the first case. MRI identified the molar tooth sign (MTS) and suggested a JSRD affection in both fetuses. The final suggested diagnosis for both cases was Joubert syndrome with intrafamilial variability in renal expression. This report describes the earliest prenatal detection of MTS. We include a discussion of the differential diagnosis of renal affection in conjunction with MTS and review the previously reported cases with prenatal MRI detection of MTS. The report emphasizes the role of MRI in the early specific prenatal diagnosis of JSRD through the recognition of MTS.

Distinguishing 3 classes of corpus callosal abnormalities in consanguineous families.

OBJECTIVE: We sought to create a classification system for pediatric corpus callosal abnormalities (CCA) based upon midline sagittal brain MRI. We used the term CCA for patients with structural variants of the corpus callosum, excluding patients with interhemispheric cyst variant or pure dysplasia without hypoplasia. Currently, no system exists for nonsyndromic forms of CCA, and attempts to create such a system have been hampered by highly variable morphology in patients with sporadic CCA. We reasoned that any useful strategy should classify affected family members within the same type, and that phenotypic variability should be minimized in patients with recessive disease. METHODS: We focused recruitment toward multiplex consanguineous families, ascertained 30 patients from 19 consanguineous families, and analyzed clinical features together with brain imaging. RESULTS: We identified 3 major CCA classes, including hypoplasia, hypoplasia with dysplasia, and complete agenesis. Affected individuals within a given multiplex family usually displayed the same variant of the class of abnormality and they always displayed the same class of abnormality within each family, or they displayed complete agenesis. The system was validated among a second cohort of 10 sporadic patients with CCA. CONCLUSIONS: The data suggest that complete agenesis may be a common end-phenotype, and implicate multiple overlapping pathways in the etiology of CCA.

Chilblains as a diagnostic sign of aicardi-goutières syndrome.

Aicardi-Goutières syndrome (AGS) is a genetically heterogeneous disorder showing variability in age of onset and clinical features. Chilblain lesions have been described in AGS patients and recent papers have discussed the clinical, molecular and cutaneous histopathological overlap with chilblain lupus. Here we report on 2 unrelated children with AGS and chilblain lesions, whose clinical histories and examination findings well illustrate the wide phenotypic variability that can be seen in this pleiotropic disorder. Although both patients show remarkable similarity in the histopathology of their associated skin lesions, with thrombi formation, fat necrosis and hyalinization of the subcutaneous tissue, we note that the histopathology reported in other AGS cases with chilblains does not necessarily demonstrate this same uniformity. Our findings highlight the significant role of the characteristic chilblain skin lesions in the diagnosis of AGS, and variability in the associated histopathology which may relate to the stage and severity of the disease.

The most encountered groups of genetic disorders in Giza Governorate, Egypt.

This study presents the prevalence, relative frequency, and analysis of genetic diseases/malformations in 73260 individuals. Cases included were ascertained from: Pediatric outpatient clinics of two governmental hospitals and two primary health care centers (PHCCs) in Giza Governorate; Neonatal intensive care unit (NICU) in the selected hospitals and Outpatients Human Genetics Clinics (NRC). 62819 persons visited the outpatients clinics of selected hospitals and PHCCs in Giza governorate. Out of these persons 731 cases (1.16%) proved to have known genetic disorders or malformations. 7755 neonates were delivered in the selected hospitals. Out of these neonates 666 newborns entered NICU and 3% (20 neonates) of them had genetic or congenital disorders. Also, 2686 patients were ascertained from the Human Genetics Clinics, NRC. The overall parental consanguinity rate among the 3417 diagnosed cases was 55%, ranging from 29.5-75%. The study showed a high prevalence of genetic/malformation disorders among Egyptians, with frequencies comparable to other Arab populations (Tab. 4, Ref. 25). Full Text (Free, PDF) www.bmj.sk.

Role of MR imaging in prenatal diagnosis of pregnancies at risk for Joubert syndrome and related cerebellar disorders.

BACKGROUND AND PURPOSE: JSRD are rare autosomal recessive brain malformations. We hypothesized that MR imaging can assess fetuses at risk for JSRD and might influence their diagnoses. MATERIALS AND METHODS: We prospectively performed cranial MR imaging for 12 fetuses (mean GA, 23 weeks; SD, 3.7) at 25% recurrence risk for JSRD. We correlated prenatal MR imaging findings with postnatal MR imaging and clinical outcome. Retrospectively, we compared posterior fossa measurements of the cases with those of 24 age-matched fetuses with proved normal brain MR imaging. Institutional review board approval and consents were obtained. Statistical methods included a t test and ANCOVA tests. RESULTS: Fetal MR imaging correctly diagnosed 3 cases at 22, 28, and 29 weeks of gestation as JSRD, and 9 cases as normal. In JSRD-affected fetuses, prenatal MR imaging detected narrow pontomesencephalic junction (isthmus) with deepening of the interpeduncular fossa and thick horizontally placed superior cerebellar peduncles (MTS), deformed anteriorly convex floor of the fourth ventricle, and midline cerebellar cleft in place of the hypoplastic vermis. Measurements on axial fetal MR imaging at pontomesencephalic junction, ratio of AP diameters of interpeduncular fossa to midbrain/isthmus, and ratio of the AP to transverse diameters of the fourth ventricle were significantly higher in JSRD-affected fetuses than in nonaffected cases and the control group. CONCLUSIONS: MR imaging can diagnose JSRD in at-risk pregnancies by detecting posterior fossa signs. Measurements at the pontomesencephalic junction may enhance fetal MR imaging accuracy in diagnosing JSRD.

Expanding CEP290 mutational spectrum in ciliopathies.

Ciliopathies are an expanding group of rare conditions characterized by multiorgan involvement, that are caused by mutations in genes encoding for proteins of the primary cilium or its apparatus. Among these genes, CEP290 bears an intriguing allelic spectrum, being commonly mutated in Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS), Senior-Loken syndrome and isolated Leber congenital amaurosis (LCA). Although these conditions are recessively inherited, in a subset of patients only one CEP290 mutation could be detected. To assess whether genomic rearrangements involving the CEP290 gene could represent a possible mutational mechanism in these cases, exon dosage analysis on genomic DNA was performed in two groups of CEP290 heterozygous patients, including five JSRD/MKS cases and four LCA, respectively. In one JSRD patient, we identified a large heterozygous deletion encompassing CEP290 C-terminus that resulted in marked reduction of mRNA expression. No copy number alterations were identified in the remaining probands. The present work expands the CEP290 genotypic spectrum to include multiexon deletions. Although this mechanism does not appear to be frequent, screening for genomic rearrangements should be considered in patients in whom a single CEP290 mutated allele was identified.

Distal 11q monosomy syndrome: a report of two Egyptian sibs with normal parental karyotypes confirmed by molecular cytogenetics.

Jacobsen syndrome is a rare disorder, caused by segmental monosomy for the distal end of the long arm of chromosome 11 with variable phenotypic expressivity. We report on the first male (6 years old) and female (3 years old) sibs with clinical and cytogenetics characterization of Jacobsen syndrome. Their karyotypes showed deletion 11q23.3-qter. Patients presented with growth and psychomotor retardation, facial dysmorphism, eye anomalies, and congenital heart disease (variable degrees of septal defect). Family history revealed a clinically similar brother, who died at 2 months old from cardiac anomalies in the form of single ventricle without being subjected to further investigations. Chromosomal analysis of the parents was normal. Karyotyping for the 2 patients and their parents was confirmed by fluorescence in situ hybridization analysis (FISH) using whole chromosome painting probes for 11 (WCP 11). Relevant investigations for both sibs showed mild thrombocytopenia with normal platelets morphology and striking periventricular demyelination on neuroimaging. Inguinal small testicles as well as focal epileptiform dysfunction were recorded in the male patient only. Abdominal ultrasound, hearing test, and DEXA scan were normal in both patients. Due to of the presence of apparently 3 affected offspring and normal parental karyotypes, an inherited predisposition was highly suspected. The large size of the distal deleted 11q segment in our patients support the recent hypothesis, that Jacobsen syndrome is a chromosomal deletion syndrome with genetic predisposition, due to expansion of p(CCG)n trinucleotide in the folate-sensitive fragile site FRA11B, at breakpoint 11q23.3. In conclusion, identification and further delineation of more similar patients will contribute to understanding the genetic basis of the 11q phenotype.