Germline Mutations in RASA1 Are Not Found in Patients with Klippel-Trenaunay Syndrome or Capillary Malformation with Limb Overgrowth.

The RASA1 gene encodes p120RASGAP, a multidomain cytoplasmic protein that acts as a negative regulator of the RAS signalling pathway. Heterozygous loss-of-function RASA1 mutations were identified in patients with Parkes Weber syndrome and multifocal capillary malformations. This syndrome is characterised by a capillary blush on an extremity, arteriovenous microfistulas, and bony and soft tissue hypertrophy. The aim of this study was to test RASA1 in 2 disorders characterised by asymmetric limb enlargement and vascular malformations, namely Klippel-Trenaunay syndrome and regional capillary malformation with overgrowth. We did not identify any clear pathogenic change in these patients. Thus, besides clinical and radiological criteria, RASA1 testing constitutes an additional tool to differentiate Parkes Weber syndrome of capillary malformation-arteriovenous malformation (CM-AVM) from overlapping disorders.

Genetic screening for nevoid basal cell carcinoma syndrome in patients with a solitary keratocystic odontogenic tumour is not useful.

AIM: The aim of this study was to investigate the need for routine genetic counselling for identification of features of nevoid basal cell carcinoma syndrome (NBCCS) in patients presenting with a solitairy keratocystic odontogenic tumour (KCOT) of the jaws. METHODS: Sixty-nine patients treated for a solitary KCOT have been followed for the possible development of second KCOTs or other signs indicative of NBCCS. In addition, 11 randomly selected patients of this group were referred for genetic counselling, including identification of germ-line mutations in the Patched gene (PTCH gene). RESULTS: In none of the 69 patients clinical and radiographic manifestations of second KCOTs and/or other features associated with NBCCS were found during a follow-up period of 49.8 months. In the 11 patients referred for genetic counselling, there were no features indicative of the presence of NBCCS. No mutations in the PTCH gene could be identified. CONCLUSION: This study does not support the need for routine genetic counselling in patients presenting with a solitairy keratocystic odontogenic tumour of the jaws.

Familial Kleefstra syndrome due to maternal somatic mosaicism for interstitial 9q34.3 microdeletions.

The Kleefstra syndrome (Online Mendelian Inheritance in Man 607001) is caused by a submicroscopic 9q34.3 deletion or by intragenic euchromatin histone methyl transferase 1 (EHMT1) mutations. So far only de novo occurrence of mutations has been reported, whereas 9q34.3 deletions can be either de novo or caused by complex chromosomal rearrangements or translocations. Here we give the first descriptions of affected parent-to-child transmission of Kleefstra syndrome caused by small interstitial deletions, approximately 200 kb, involving part of the EHMT1 gene. Additional genome-wide array studies in the parents showed the presence of similar deletions in both mothers who only had mild learning difficulties and minor facial characteristics suggesting either variable clinical expression or somatic mosaicism for these deletions. Further studies showed only one of the maternal deletions resulted in significantly quantitative differences in signal intensity on the array between the mother and her child. But by investigating different tissues with additional fluorescent in situ hybridization (FISH) and multiplex ligation-dependent probe amplification (MLPA) analyses, we confirmed somatic mosaicism in both mothers. Careful clinical and cytogenetic assessments of parents of an affected proband with an (interstitial) 9q34.3 microdeletion are merited for accurate estimation of recurrence risk.

[A neonate with a congenital hand defect]. / Een neonaat met een aangeboren handafwijking.

A newborn presented with a birth defect of his left hand and unilateral hypoplasia of his left musculus pectoralis major and left nipple. He was diagnosed with Poland syndrome.

Rendu-Osler-Weber disease: update of medical and dental considerations.

Rendu-Osler-Weber disease, also known as hereditary hemorrhagic telangiectasia (HHT), is an autosomal dominant inherited disorder characterized by an aberrant vascular development. The reported prevalence is approximately 1 per 5,000-10,000. The clinical manifestations consist of recurrent spontaneous nosebleeds, telangiectasias characteristically at the lips, oral cavity, fingers, and nose, and visceral arteriovenous malformations. Timely recognition of this syndrome makes screening for complications, preventive measurements, and genetic counselling possible. The important role of the dental profession in the recognition of this genetic disease is emphasized. In addition, a brief overview of the current literature is presented.

Feasibility and outcomes of multiplex ligation-dependent probe amplification on buccal smears as a screening method for microdeletions and duplications among 300 adults with an intellectual disability of unknown aetiology.

BACKGROUND: Determining the aetiology of intellectual disability (ID) enables anticipation of specific comorbidity and can thus be beneficial. Blood sampling, however, is considered stressful for people with ID. Our aim was to evaluate the feasibility of a non-invasive screening technique of nine microdeletions/duplications among adults with ID of unknown aetiology. METHODS: In a random sample of 300 adult clients of Dutch ID services without an aetiological diagnosis, DNA was collected on site using oral swabs. Multiplex Ligation-dependent Probe Amplification was applied to screen for nine microdeletions/duplications related to ID syndromes (Williams 22q11-deletion, 1p-deletion, Miller-Dieker, Smith-Magenis, Prader-Willi, Alagille, Saethre-Chotzen and Sotos syndrome). RESULTS: Feasibility: prior to the consent procedure, for 2.1% (10/471 eligible participants), the method was considered undesirable. In 0.7% (2/300 participants) oral swabs failed because of resistant behaviour, while in 16.1% (48/298 swabs) analysis was unsuccessful because of insufficient amounts of DNA. A repeated attempt yielded an equal success rate. Outcome Microdeletions were diagnosed in four participants: 22q11 deletion (n = 2), 5q35 deletion (Sotos syndrome) (n = 1) and 1p deletion (n = 1). One participant had a duplication of the Prader-Willi Region (15q11-13) owing to mosaicism of a supernumerary marker chromosome (15). CONCLUSIONS: Oral swabs are a feasible method for DNA sampling in adults with IDs. A diagnosis could be made in five out of 275 people with ID of unknown aetiology. After screening, in the total population sample (n = 620), the prevalence of syndromes associated with the microdeletions/duplications studied was at least 2.3% (95% confidence interval 1.1-3.4%).

Contribution of CYLN2 and GTF2IRD1 to neurological and cognitive symptoms in Williams Syndrome.

Williams Syndrome (WS, [MIM 194050]) is a disorder caused by a hemizygous deletion of 25-30 genes on chromosome 7q11.23. Several of these genes including those encoding cytoplasmic linker protein-115 (CYLN2) and general transcription factors (GTF2I and GTF2IRD1) are expressed in the brain and may contribute to the distinct neurological and cognitive deficits in WS patients. Recent studies of patients with partial deletions indicate that hemizygosity of GTF2I probably contributes to mental retardation in WS. Here we investigate whether CYLN2 and GTF2IRD1 contribute to the motoric and cognitive deficits in WS. Behavioral assessment of a new patient in which STX1A and LIMK1, but not CYLN2 and GTF2IRD1, are deleted showed that his cognitive and motor coordination functions were significantly better than in typical WS patients. Comparative analyses of gene specific CYLN2 and GTF2IRD1 knockout mice showed that a reduced size of the corpus callosum as well as deficits in motor coordination and hippocampal memory formation may be attributed to a deletion of CYLN2, while increased ventricle volume can be attributed to both CYLN2 and GTF2IRD1. We conclude that the motor and cognitive deficits in Williams Syndrome are caused by a variety of genes and that heterozygous deletion of CYLN2 is one of the major causes responsible for such dysfunctions.

A report on 10 new patients with heterozygous mutations in the COL11A1 gene and a review of genotype-phenotype correlations in type XI collagenopathies.

A series of 44 unrelated patients in whom COL2A1 screening demonstrated normal results but whose phenotype was nevertheless highly suggestive of either Stickler syndrome (with ocular involvement) or Marshall syndrome were investigated for mutations in the COL11A1 gene. Heterozygous COL11A1 mutations were found in 10 individuals. A splice site alteration (involving introns 47-55) was present in seven cases, with one in intron 50 (c.3816 + 1G > A) occurring in three patients. Two patients had a different deletion, and a missense mutation (Gly1471Asp) was observed in one case. In 4/10 patients the phenotype was classified as Marshall syndrome because of early-onset severe hearing loss and characteristic facial features. These four patients were all heterozygous for a splice site mutation in intron 50. One of these cases had a type 1 vitreous anomaly despite the presence of a COL11A1 mutation. The remaining 6/10 patients had an overlapping Marshall-Stickler phenotype with less pronounced facial features. None of these had a mutation in the hot spot region of intron 50.

Regional underreporting of associated congenital anomalies in cleft patients in the Netherlands.

OBJECTIVE: The Dutch Cleft Palate Association (DCPA) registers all patients with cleft lip or palate and associated congenital anomalies in the Netherlands. The aim of this study was to assess if early registration of cleft patients leads to underreporting of associated congenital anomalies and, if so, whether reregistration is necessary. METHODS: The DCPA registration of the birth cohort 1997 to 2001 was compared with the medical files of these cleft patients for prevalence, type, and moment of registration of associated congenital anomalies. To assess possible long-term underregistration, a second birth cohort of 1990 to 1991 was analyzed. RESULTS: The percentage of cleft patients with associated congenital anomalies was 26% in the DCPA database and 33% in the retrospective medical file review. A syndrome, sequence, or association was recognized in 8% of the cleft patients by the DCPA compared with 13% in our medical file review. Of all associated congenital anomalies diagnosed during a follow-up of 12 years, 53% were diagnosed in the first year of life. The cumulative percentage was 59% after 2 years, 62% after 3 years, 80% after 6 years, and 97% after 10 years. CONCLUSION: Early registration of cleft patients leads to underreporting of other associated anomalies. For a complete registration of associated congenital anomalies in cleft patients, reregistration at a later age is necessary.

Two cases of severe neonatal hypertrophic cardiomyopathy caused by compound heterozygous mutations in the MYBPC3 gene.

BACKGROUND: Idiopathic (primary) hypertrophic cardiomyopathy (HCM) is mainly caused by mutations in genes encoding sarcomeric proteins. One of the most commonly mutated HCM genes is the myosin binding protein C (MYBPC3) gene. Mutations in this gene lead mainly to truncation of the protein which gives rise to a relatively mild phenotype. Pure HCM in neonates is rare and most of the time childhood HCM occurs in association with another underlying condition. OBJECTIVE: To study the presence of mutations in the MYBPC3 gene in idiopathic childhood HCM. METHODS: MYBPC3 coding region and splice junction variation were analysed by denaturing high performance liquid chromatography (DHPLC) and sequencing in DNA isolated from two neonates with severe unexplained HCM, who died within the first weeks of life. RESULTS: Truncating mutations were found in both alleles of the MYBPC3 gene in both patients, suggesting there was no functional copy of the MYBPC3 protein. Patient 1 carried the maternally inherited c.2373_2374insG mutation and the paternally inherited splice-donor site mutation c.1624+1G-->A. Patient 2 carried the maternally inherited frameshift mutation c.3288delA (p.Glu1096fsX92) and the paternally inherited non-sense mutation c.2827C-->T (p.Arg943X). CONCLUSIONS: The findings indicate the need for mutation analysis of genes encoding sarcomeric proteins in childhood HCM and the possibility of compound heterozygosity.

CHARGE syndrome: the phenotypic spectrum of mutations in the CHD7 gene.

BACKGROUND: CHARGE syndrome is a non-random clustering of congenital anomalies including coloboma, heart defects, choanal atresia, retarded growth and development, genital hypoplasia, ear anomalies, and deafness. A consistent feature in CHARGE syndrome is semicircular canal hypoplasia resulting in vestibular areflexia. Other commonly associated congenital anomalies are facial nerve palsy, cleft lip/palate, and tracheo-oesophageal fistula. Specific behavioural problems, including autistic-like behaviour, have been described. The CHD7 gene on chromosome 8q12.1 was recently discovered as a major gene involved in the aetiology of this syndrome. METHODS: The coding regions of CHD7 were screened for mutations in 107 index patients with clinical features suggestive of CHARGE syndrome. Clinical data of the mutation positive patients were sampled to study the phenotypic spectrum of mutations in the CHD7 gene. RESULTS: Mutations were identified in 69 patients. Here we describe the clinical features of 47 of these patients, including two sib pairs. Most mutations were unique and were scattered throughout the gene. All patients but one fulfilled the current diagnostic criteria for CHARGE syndrome. No genotype-phenotype correlations were apparent in this cohort, which is best demonstrated by the differences in clinical presentation in sib pairs with identical mutations. Somatic mosaicism was detected in the unaffected mother of a sib pair, supporting the existence of germline mosaicism. CONCLUSIONS: CHD7 mutations account for the majority of the cases with CHARGE syndrome, with a broad clinical variability and without an obvious genotype-phenotype correlation. In one case evidence for germline mosaicism was provided.

Increased prevalences of left-handedness and left-eye sighting dominance in individuals with Williams-Beuren syndrome.

Handedness and eye sighting dominance were assessed in a sample of 50 individuals (25 male, 25 female; aged 5-38 years) with Williams-Beuren syndrome (WBS). The prevalences of left-handedness and left-eyedness were compared to the normative prevalences in the general population. We found significantly higher prevalences of left-handedness and left-eyedness in the WBS sample. The higher prevalences were more salient in younger than in older individuals and in male than in female individuals. We suggest that the increased prevalence of left-handedness in WBS is a consequence of a slower maturation rate, which allows deviation from a predetermined laterality pattern.

[Restrictive dermopathy: a rare, lethal genodermatosis]. / Restrictieve dermopathie: een zeldzame, letale genodermatose.

In a premature male infant born of consanguineous parents, restrictive dermopathy was diagnosed. This is a rarely described, lethal, congenital skin disease. The diagnosis was based on the clinical and histopathological findings: a fixed facial expression (so-called 'porcelain face') with palpebral fissures inclined laterally downwards, microstomia with the mouth in the 'O'-position, micrognathia and low-set ears inclined toward the rear, prominent blood vessels in the skin and contracture of all the joints; histopathological examination of a skin biopsy revealed a smooth epidermis and a relatively thin dermis with an abnormal structure of the dermal connective tissue in which the collagen fibres were arranged more or less horizontally, parallel to the epidermis, and the number of elastin fibres was sharply decreased. Various adnexal structures were present but the hair follicles had an abortive appearance. Thanks in part to the finding of a homozygous mutation in the so-called ZMPSTE24-gene, it could be concluded that restrictive dermopathy is probably an autosomal recessive laminopathy, related to progeria. Increasing the clinical awareness of this disease may contribute to reducing the presumed under-reporting, so that future research will become possible.

Interstitial deletion in 3q in a patient with blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) and microcephaly, mild mental retardation and growth delay: clinical report and review of the literature.

We present a boy with blepharophimosis, ptosis, epicanthus inversus, microcephaly, mild mental retardation, and growth delay. Chromosomal analysis revealed a male karyotype with an interstitial deletion in the long arm of chromosome 3. DNA-analysis showed that the deletion is of maternal origin and encompasses the region between markers D3S1535 and D3S1593. The deletion contains not only the FOXL2 gene, but also the gene encoding ataxia-telangiectasia and Rad3-related protein (ATR). Mutations in FOXL2 have been shown to cause blepharophimosis-ptosis-epicanthus inversus syndrome (BPES). ATR has been identified as a candidate gene for Seckel syndrome, an autosomal recessive syndrome that comprises growth retardation, microcephaly, and mental retardation. We hypothesize that our patient has a contiguous gene syndrome and that the non-BPES-associated abnormalities (microcephaly, mild mental retardation, and growth delay) are the result of the deletion of the maternal ATR gene. However, it has not yet been excluded that haploinsufficiency of some other gene in this region plays a role.

Visual depth processing in Williams-Beuren syndrome.

Patients with Williams-Beuren Syndrome (WBS, also known as Williams Syndrome) show many problems in motor activities requiring visuo-motor integration, such as walking stairs. We tested to what extent these problems might be related to a deficit in the perception of visual depth or to problems in using this information in guiding movements. Monocular and binocular visual depth perception was tested in 33 patients with WBS. Furthermore, hand movements to a target were recorded in conditions with and without visual feedback of the position of the hand. The WBS group was compared to a group of control subjects. The WBS patients were able to perceive monocular depth cues that require global processing, but about 49% failed to show stereopsis. On average, patients with WBS moved their hand too far when no visual feedback on hand position was given. This was not so when they could see their hand. Patients with WBS are able to derive depth from complex spatial relationships between objects. However, they seem to be impaired in using depth information for guiding their movements when deprived of visual feedback. We conclude that the problems that WBS patients have with tasks such as descending stairs are not due to an inability to judge distance.

[From gene to disease; EVC, EVC2, and Ellis-van Creveld syndrome]. / Van gen naar ziekte; EVC, EVC2 en Ellis-van Creveld-syndroom.

Ellis-van Creveld syndrome is an autosomal recessive disorder characterised by short stature with short limbs, postaxial polydactyly and congenital cardiac defects. The syndrome can be caused by mutations in the EVC gene or the EVC2 gene. The genes are located close to each other in a head-to-head configuration on chromosome 4p16. Clinical diagnosis can be confirmed by DNA analysis, which is currently offered by two laboratories in Italy.

[From gene to disease: basal cell naevus syndrome]. / Van gen naar ziekte; basaalcelnaevussyndroom.

Nevoid basal cell carcinoma syndrome (NBCCS, basal cell naevus syndrome, Gorlin syndrome) is an autosomal dominant disorder, caused by mutations in the PTCH gene mapped to chromosome 9q22.3. It is characterised by multiple basal cell carcinomas, keratocysts of the jaws, palmar and plantar pits, cerebral ectopic calcification and several skeletal anomalies. Occasionally, patients with NBCCS develop other neoplasms, particularly medulloblastomas and ovarian fibromas, indicating that the PTCH gene is a tumor-suppressor gene. Early recognition and careful follow-up are needed. Guidelines for managing these patients are presented.

Clinical presentations of patients with polyol abnormalities.

Since our description of a patient with leukoencephalopathy and highly elevated polyols in the brain and body fluids, we started screening for polyol abnormalities in patients highly suspected of a metabolic disorder. We identified four additional patients with consistent abnormalities in sugar and polyol profiles in body fluids. The clinical, neuroimaging, and biochemical findings of the five patients detected so far are described in the present paper. In four patients neurological problems dominated the clinical picture, whereas liver failure dominated in the other patient. The sugar and polyol profiles were abnormal in body fluids in all patients, but the profiles were different in individual patients. A deficiency of transaldolase was found in the patient presenting with liver failure. We were not able to identify the basic defect in the four patients with predominantly neurological problems. The differences in clinical picture, MRI abnormalities, and sugar and polyol profiles in these patients suggest that the underlying defects may be different. Whether the abnormal sugar and polyol profiles are directly related to the cause of disease via defects in polyol metabolism or transport remains to be elucidated.

Saccade dysmetria in Williams-Beuren syndrome.

Numerous studies have described the poor visuo-spatial processing capacities of subjects with Williams-Beuren syndrome (WBS), a genetically based developmental disorder. Since visual perception and eye movements are closely related we hypothesized that the poor visuo-spatial processing capacities of subjects with WBS might be related to a poor saccadic control. Thereto, we recorded horizontal and vertical saccadic eye movements to targets using infrared video-oculography in 27 subjects with WBS and eight healthy controls. In the WBS group saccadic gains were highly variable, both between and within individual subjects, and they often needed more than one correction saccade to reach the target. Ten (out of a subgroup of 22) WBS subjects showed a large number of hypometric and/or hypermetric saccades, and, also a left-right asymmetry in saccadic gains was observed in WBS. We conclude that the observed impairments in saccadic control are likely to affect the proper processing of visuo-spatial information.