Mutations in THAP11 cause an inborn error of cobalamin metabolism and developmental abnormalities.

CblX (MIM309541) is an X-linked recessive disorder characterized by defects in cobalamin (vitamin B12) metabolism and other developmental defects. Mutations in HCFC1, a transcriptional co-regulator which interacts with multiple transcription factors, have been associated with cblX. HCFC1 regulates cobalamin metabolism via the regulation of MMACHC expression through its interaction with THAP11, a THAP domain-containing transcription factor. The HCFC1/THAP11 complex potentially regulates genes involved in diverse cellular functions including cell cycle, proliferation, and transcription. Thus, it is likely that mutation of THAP11 also results in biochemical and other phenotypes similar to those observed in patients with cblX. We report a patient who presented with clinical and biochemical phenotypic features that overlap cblX, but who does not have any mutations in either MMACHC or HCFC1. We sequenced THAP11 by Sanger sequencing and discovered a potentially pathogenic, homozygous variant, c.240C > G (p.Phe80Leu). Functional analysis in the developing zebrafish embryo demonstrated that both THAP11 and HCFC1 regulate the proliferation and differentiation of neural precursors, suggesting important roles in normal brain development. The loss of THAP11 in zebrafish embryos results in craniofacial abnormalities including the complete loss of Meckel's cartilage, the ceratohyal, and all of the ceratobranchial cartilages. These data are consistent with our previous work that demonstrated a role for HCFC1 in vertebrate craniofacial development. High throughput RNA-sequencing analysis reveals several overlapping gene targets of HCFC1 and THAP11. Thus, both HCFC1 and THAP11 play important roles in the regulation of cobalamin metabolism as well as other pathways involved in early vertebrate development.

DVL1 frameshift mutations clustering in the penultimate exon cause autosomal-dominant Robinow syndrome.

Robinow syndrome is a genetically heterogeneous disorder characterized by mesomelic limb shortening, genital hypoplasia, and distinctive facial features and for which both autosomal-recessive and autosomal-dominant inheritance patterns have been described. Causative variants in the non-canonical signaling gene WNT5A underlie a subset of autosomal-dominant Robinow syndrome (DRS) cases, but most individuals with DRS remain without a molecular diagnosis. We performed whole-exome sequencing in four unrelated DRS-affected individuals without coding mutations in WNT5A and found heterozygous DVL1 exon 14 mutations in three of them. Targeted Sanger sequencing in additional subjects with DRS uncovered DVL1 exon 14 mutations in five individuals, including a pair of monozygotic twins. In total, six distinct frameshift mutations were found in eight subjects, and all were heterozygous truncating variants within the penultimate exon of DVL1. In five families in which samples from unaffected parents were available, the variants were demonstrated to represent de novo mutations. All variant alleles are predicted to result in a premature termination codon within the last exon, escape nonsense-mediated decay (NMD), and most likely generate a C-terminally truncated protein with a distinct -1 reading-frame terminus. Study of the transcripts extracted from affected subjects' leukocytes confirmed expression of both wild-type and variant alleles, supporting the hypothesis that mutant mRNA escapes NMD. Genomic variants identified in our study suggest that truncation of the C-terminal domain of DVL1, a protein hypothesized to have a downstream role in the Wnt-5a non-canonical pathway, is a common cause of DRS.

Enhanced maternal origin of the 22q11.2 deletion in velocardiofacial and DiGeorge syndromes.

Velocardiofacial and DiGeorge syndromes, also known as 22q11.2 deletion syndrome (22q11DS), are congenital-anomaly disorders caused by a de novo hemizygous 22q11.2 deletion mediated by meiotic nonallelic homologous recombination events between low-copy repeats, also known as segmental duplications. Although previous studies exist, each was of small size, and it remains to be determined whether there are parent-of-origin biases for the de novo 22q11.2 deletion. To address this question, we genotyped a total of 389 DNA samples from 22q11DS-affected families. A total of 219 (56%) individuals with 22q11DS had maternal origin and 170 (44%) had paternal origin of the de novo deletion, which represents a statistically significant bias for maternal origin (p = 0.0151). Combined with many smaller, previous studies, 465 (57%) individuals had maternal origin and 345 (43%) had paternal origin, amounting to a ratio of 1.35 or a 35% increase in maternal compared to paternal origin (p = 0.000028). Among 1,892 probands with the de novo 22q11.2 deletion, the average maternal age at time of conception was 29.5, and this is similar to data for the general population in individual countries. Of interest, the female recombination rate in the 22q11.2 region was about 1.6-1.7 times greater than that for males, suggesting that for this region in the genome, enhanced meiotic recombination rates, as well as other as-of-yet undefined 22q11.2-specific features, could be responsible for the observed excess in maternal origin.

The Danish 22q11 research initiative.

BACKGROUND: Neurodevelopmental brain disorders such as schizophrenia, autism and attention deficit hyperactivity disorder are complex disorders with heterogeneous etiologies. Schizophrenia and autism are difficult to treat and often cause major individual suffering largely owing to our limited understanding of the disease biology. Thus our understanding of the biological pathogenesis needs to be substantiated to enable development of more targeted treatment options with improved efficacy. Insights into the pre-morbid disease dynamics, the morbid condition and the underlying biological disease mechanisms may come from studies of subjects with homogenous etiologies. Breakthroughs in psychiatric genetics have shown that several genetic anomalies predispose for neurodevelopmental brain disorders. We have established a Danish research initiative to study the common microdeletion at chromosome 22q11.2, which is one of the genetic anomalies that confer high risk of schizophrenia, autism and attention deficit hyperactivity disorder. METHODS/DESIGN: The study applies a "cause-to-outcome" strategy to identify pre-morbid pathogenesis and underlying biological disease mechanisms of psychosis and secondarily the morbid condition of autism and attention deficit hyperactivity disorder. We use a population based epidemiological design to inform on disease prevalence, environmental risk factors and familial disposition for mental health disorders and a case control study design to map the functional effects across behavioral and neurophysiological traits of the 22q11 deletion in a recruited sample of Danish individuals. DISCUSSION: Identification of predictive pre-morbid clinical, cognitive, functional and structural brain alterations in 22q11 deletion carriers may alter current clinical practice from symptomatic therapy of manifest mental illness into early intervention strategies, which may also be applicable to at risk subjects without known etiology. Hopefully new insights into the biological disease mechanisms, which are mandatory for novel drug developments, can improve the outcome of the pharmacological interventions in psychiatry.

Penetrance of hypertrophic cardiomyopathy in children and adolescents: a 12-year follow-up study of clinical screening and predictive genetic testing.

BACKGROUND: The penetrance of hypertrophic cardiomyopathy (HCM) during childhood and adolescence has been only sparsely described. We studied the penetrance of HCM and the short- and long-term outcomes of clinical screening and predictive genetic testing of child relatives of patients with HCM. METHODS AND RESULTS: Ninety probands and 361 relatives were included in a family screening program for HCM (1994-2001). Eleven sarcomere genes, CRYAB, α-GAL, and titin were screened. Sixty-six relatives and 4 probands were <18 years of age at inclusion. Twelve child relatives were mutation carriers (age, 12 ± 5 years), and 26 had unknown genetic status, ie, relatives from families without identified mutations (n = 21) or not tested (n = 5) (age, 11 ± 5 years). Twenty-eight noncarriers (42%; age, 10 ± 4 years) served as control subjects. Two of 38 child relatives (5%) at risk of developing HCM fulfilled diagnostic criteria for HCM at inclusion. After 12 ± 1 years of follow-up, 2 of the 36 (6%; 95% confidence interval, 2-18) at-risk child relatives who were phenotype negative at inclusion had developed the HCM phenotype at 26 and 28 years of age. During follow-up, none of the child relatives experienced serious cardiac events. Participation in the screening program had no long-term negative psychological impact. CONCLUSIONS: The penetrance of HCM in phenotype-negative child relatives at risk of developing HCM was 6% after 12 years of follow-up. The finding of phenotype conversion in the mid-20s warrants continued screening into adulthood. Forty-two percent of the child relatives were noncarriers, and repeat clinical follow-up could be safely limited to the remaining children.

Copper deficiency in patients with cystinosis with cysteamine toxicity.

OBJECTIVES: To assess whether copper deficiency plays a role in the recently described cysteamine toxicity in patients with cystinosis, and to examine whether polymorphisms in copper transporters, lysyl oxidase, and/or type I procollagen genes could be responsible for the occurrence of cysteamine toxicity in a small subset of patients with cystinosis. STUDY DESIGN: Thirty-six patients with cystinosis were included: 22 with Fanconi syndrome (including 7 with cysteamine toxicity), 12 after renal transplantation, 1 receiving hemodialysis, and 1 with ocular cystinosis. Serum copper and ceruloplasmin levels and urinary copper/creatinine ratio were measured. Genes ATP7A and CTR1 (encoding copper transporters), LOX (encoding lysyl oxidase), and COL1A1 and COL1A2 (encoding type I procollagen) were analyzed in patients with (n = 6) and without (n = 5) toxicity. Fibroblast (pro)collagen synthesis was compared in patients with (n = 3) and those without (n = 2) cysteamine toxicity. RESULTS: All 22 patients with Fanconi syndrome had increased urinary copper excretion. Serum copper and ceruloplasmin levels were decreased in 9 patients, including all 7 patients with cysteamine toxicity. No specific sequence variations were associated with toxicity. All fibroblasts exhibited normal (pro)collagen synthesis. CONCLUSION: Patients with cystinosis with cysteamine toxicity demonstrate copper deficiency. This can cause decreased activity of lysyl oxidase, the enzyme that generates the aldehydes required for collagen cross-linking. Thus, copper supplementation might prevent cysteamine toxicity.

Disease-associated mutations in the actin-binding domain of filamin B cause cytoplasmic focal accumulations correlating with disease severity.

Dominant missense mutations in FLNB, encoding the actin-cross linking protein filamin B (FLNB), cause a broad range of skeletal dysplasias with varying severity by an unknown mechanism. Here these FLNB mutations are shown to cluster in exons encoding the actin-binding domain (ABD) and filamin repeats surrounding the flexible hinge 1 region of the FLNB rod domain. Despite being positioned in domains that bind actin, it is unknown if these mutations perturb cytoskeletal structure. Expression of several full-length FLNB constructs containing ABD mutations resulted in the appearance of actin-containing cytoplasmic focal accumulations of the substituted protein to a degree that was correlated with the severity of the associated phenotypes. In contrast, study of mutations leading to substitutions in the FLNB rod domain that result in the same phenotypes as ABD mutations demonstrated that with only one exception disease-associated substitutions, surrounding hinge 1 demonstrated no tendency to form actin-filamin foci. The exception, a substitution in filamin repeat 6, lies within a region previously implicated in filamin-actin binding. These data are consistent with mutations in the ABD conferring enhanced actin-binding activity but suggest that substitutions affecting repeats near the flexible hinge region of FLNB precipitate the same phenotypes through a different mechanism.

MCAD deficiency in Denmark.

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the most common defect of fatty acid oxidation. Many countries have introduced newborn screening for MCADD, because characteristic acylcarnitines can easily be identified in filter paper blood spot samples by tandem mass spectrometry (MS/MS), because MCADD is a frequent disease, and because of the success of early treatment initiated before clinical symptoms have emerged. In Denmark we have screened 519,350 newborns for MCADD by MS/MS and identified 58 affected babies. The diagnosis of MCADD was confirmed in all 58 newborns by mutation analysis. This gives an incidence of MCADD detected by newborn screening in Denmark of 1/8954. In sharp contrast to this we found that the incidence of clinically presenting MCADD in Denmark in the 10 year period preceding introduction of MS/MS-based screening was only 1 in 39,691. This means that four times more newborns with MCADD are detected by screening than what is expected based on the number of children presenting clinically in an unscreened population. The mutation spectrum in the newborns detected by screening is different from that observed in clinically presenting patients with a much lower proportion of newborns being homozygous for the prevalent disease-causing c.985A>G mutation. A significant number of the newborns have genotypes with mutations that have not been observed in patients detected clinically. Some of these mutations, like c.199T>C and c.127G>A, are always associated with a milder biochemical phenotype and may cause a milder form of MCADD with a relatively low risk of disease manifestation, thereby explaining part of the discrepancy between the frequency of clinically manifested MCADD and the frequency of MCADD determined by screening. In addition, our data suggest that some of this discrepancy can be explained by a reduced penetrance of the c.985A>G mutation, with perhaps only 50% of c.985A>G homozygotes presenting with disease manifestations. Interestingly, we also report that the observed number of newborns identified by screening who are homozygous for the c.985A>G mutation is twice that predicted from the estimated carrier frequency. We therefore redetermined the carrier frequency in a new sample of 1946 blood spots using a new assay, but this only confirmed that the c.985A>G carrier frequency in Denmark is approximately 1/105. We conclude that MCADD is much more frequent than expected, has a reduced penetrance and that rapid genotyping using the initial blood spot sample is important for correct diagnosis and counseling.

Biochemical screening of 504,049 newborns in Denmark, the Faroe Islands and Greenland--experience and development of a routine program for expanded newborn screening.

Expanded newborn screening for selected inborn errors of metabolism (IEM) in Denmark, the Faroe Islands and Greenland was introduced in 2002. We now present clinical, biochemical, and statistical results of expanded screening (excluding PKU) of 504,049 newborns during nine years as well as diagnoses and clinical findings in 82,930 unscreened newborns born in the same period. The frequencies of diagnoses made within the panel of disorders screened for are compared with the frequencies of the disorders in the decade preceding expanded newborn screening. The expanded screening was performed as a pilot study during the first seven years, and the experience obtained during these years was used in the development of the routine neonatal screening program introduced in 2009. Methods for screening included tandem mass spectrometry and an assay for determination of biotinidase activity. A total of 310 samples from 504,049 newborns gave positive screening results. Of the 310 results, 114 were true positive, including results from 12 newborns in which the disease in question was subsequently diagnosed in their mothers. Thus, the overall frequency of an IEM in the screening panel was 1:4942 (mothers excluded) or 1:4421 (mothers included). The false positive rate was 0.038% and positive predictive value 37%. Overall specificity was 99.99%. All patients with true positive results were followed in The Center for Inherited Metabolic Disorders in Copenhagen, and the mean follow-up period was 45 months (range 2109 months). There were no deaths among the 102 children, and 94% had no clinically significant sequelae at last follow-up. Our study confirms the higher frequency of selected IEM after implementation of expanded newborn screening and suggests an improved outcome for several disorders. We argue that newborn screening for these disorders should be standard of care, though unresolved issues remain, e.g. about newborns with a potential for remaining asymptomatic throughout life. Well organized logistics of the screening program from screening laboratory to centralized, clinical management is important.

Cysteamine toxicity in patients with cystinosis.

OBJECTIVE: To report new adverse effects of cysteamine. STUDY DESIGN: Detailed clinical information was obtained from the patients' physicians. RESULTS: New adverse events were reported in 8 of 550 patients with cystinosis treated with cysteamine in Europe during the last 5 years. Detailed clinical information was not available for 2 of these patients, 1 of whom died from cerebral ischemia. The 6 evaluable patients developed vascular elbow lesions (6/6), neurologic symptoms (1/6), bone and muscle pain (2/6), and/or skin striae (2/6). Analysis of biopsy specimens from the elbow lesions demonstrated angioendotheliomatosis with irregular collagen fibers. In 3 of the 6 patients, the daily cysteamine dose exceeded the recommended maximum of 1.95 g/m(2)/day. Dose reduction led to improvement of signs and symptoms in all 6 patients, suggesting a causal relationship with cysteamine administration. CONCLUSION: Cysteamine administration can be complicated by the development of skin, vascular, neurologic, muscular, and bone lesions. These lesions improve after cysteamine dose reduction. Doses >1.95 g/m(2)/day should be prescribed with great caution, but underdosing is not advocated.

The molecular mechanism underlying Roberts syndrome involves loss of ESCO2 acetyltransferase activity.

Roberts syndrome/SC phocomelia (RBS) is an autosomal recessive disorder with growth retardation, craniofacial abnormalities and limb reduction. Cellular alterations in RBS include lack of cohesion at the heterochromatic regions around centromeres and the long arm of the Y chromosome, reduced growth capacity, and hypersensitivity to DNA damaging agents. RBS is caused by mutations in ESCO2, which encodes a protein belonging to the highly conserved Eco1/Ctf7 family of acetyltransferases that is involved in regulating sister chromatid cohesion. We identified 10 new mutations expanding the number to 26 known ESCO2 mutations. We observed that these mutations result in complete or partial loss of the acetyltransferase domain except for the only missense mutation that occurs in this domain (c.1615T>G, W539G). To investigate the mechanism underlying RBS, we analyzed ESCO2 mutations for their effect on enzymatic activity and cellular phenotype. We found that ESCO2 W539G results in loss of autoacetyltransferase activity. The cellular phenotype produced by this mutation causes cohesion defects, proliferation capacity reduction and mitomycin C sensitivity equivalent to those produced by frameshift and nonsense mutations associated with decreased levels of mRNA and absence of protein. We found decreased proliferation capacity in RBS cell lines associated with cell death, but not with increased cell cycle duration, which could be a factor in the development of phocomelia and cleft palate in RBS. In summary, we provide the first evidence that loss of acetyltransferase activity contributes to the pathogenesis of RBS, underscoring the essential role of the enzymatic activity of the Eco1p family of proteins.

Tissue-specific amino acid transporter partners ACE2 and collectrin differentially interact with hartnup mutations.

BACKGROUND & AIMS: Hartnup amino acid transporter B(0)AT1 (SLC6A19) is the major luminal sodium-dependent neutral amino acid transporter of small intestine and kidney proximal tubule. The expression of B(0)AT1 in kidney was recently shown to depend on its association with collectrin (Tmem27), a protein homologous to the membrane-anchoring domain of angiotensin-converting enzyme (ACE) 2. METHODS: Because collectrin is almost absent from small intestine, we tested the hypothesis that it is ACE2 that interacts with B(0)AT1 in enterocytes. Furthermore, because B(0)AT1 expression depends on an associated protein, we tested the hypothesis that Hartnup-causing B(0)AT1 mutations differentially impact on B(0)AT1 interaction with intestinal and kidney accessory proteins. RESULTS: Immunofluorescence, coimmunoprecipitation, and functional experiments using wild-type and ace2-null mice showed that expression of B(0)AT1 in small intestine critically depends on ACE2. Coexpressing new and previously identified Hartnup disorder-causing missense mutations of B(0)AT1 with either collectrin or ACE2 in Xenopus laevis oocytes showed that the high-frequency D173N and the newly identified P265L mutant B(0)AT1 transporters can still be activated by ACE2 but not collectrin coexpression. In contrast, the human A69T and R240Q B(0)AT1 mutants cannot be activated by either of the associated proteins, although they function as wild-type B(0)AT1 when expressed alone. CONCLUSIONS: We thus show that ACE2 is necessary for the expression of the Hartnup transporter in intestine and suggest that the differential functional association of mutant B(0)AT1 transporters with ACE2 and collectrin in intestine and kidney, respectively, participates in the phenotypic heterogeneity of human Hartnup disorder.

A revisit to the natural history of homocystinuria due to cystathionine beta-synthase deficiency.

We review the evidence that in Denmark and probably certain other European countries the number of individuals identified with homocystinuria due to homozygosity for the widespread c.833T>C (p.I278T) mutation in the gene that encodes cystathionine beta-synthase (CBS) falls far short of the number of such individuals expected on the basis of the heterozygote frequency for this mutation found by molecular screening. We conclude that the predominant portion of such homozygotes may be clinically unaffected, or may be ascertained for thromboembolic events occurring no sooner than the third decade of life. If so, there was significant ascertainment bias in the time-to-event curves previously published describing the natural history of untreated CBS deficiency Mudd et al. and these curves should be used with care.

OPA3, mutated in 3-methylglutaconic aciduria type III, encodes two transcripts targeted primarily to mitochondria.

3-Methylglutaconic aciduria type III (3-MGCA type III), caused by recessive mutations in the 2-exon gene OPA3, is characterized by early-onset bilateral optic atrophy, later-onset extrapyramidal dysfunction, and increased urinary excretion of 3-methylglutaconic acid and 3-methylglutaric acid. Here we report the identification of a novel third OPA3 coding exon, the apparent product of a segmental duplication event, resulting in two gene transcripts, OPA3A and OPA3B. OPA3A deficiency (as in optic atrophy type 3) causes up-regulation of OPA3B. OPA3 protein function remains unknown, but it contains a putative mitochondrial leader sequence, mitochondrial sorting signal and a peroxisomal sorting signal. Our green fluorescent protein tagged OPA3 expression studies found its localization to be predominantly mitochondrial. These findings thus place the cellular metabolic defect of 3-MGCA type III in the mitochondrion rather than the peroxisome and implicate loss of OPA3A rather than gain of OPA3B in disease etiology.

Clinical and biochemical monitoring of patients with fatty acid oxidation disorders.

Evidence-based guidelines for monitoring patients with disorders in fatty acid oxidation (FAO) are lacking, and most protocols are based on expert statements. Here, we describe our protocol for Danish patients. Clinical monitoring is the most important measure and has the main aims of checking growth, development and diet and of bringing families to the clinic regularly to remind them of their child's risk and review how they cope and adjust, e.g. to an acute intercurrent illness. Most of these measures are simple and can be carried out during a routine out-patient visit; we seldom do more complicated assessments by a neuropsychologist, speech therapist, or physical and occupational therapists. Paraclinical measurements are not used for short-chain and medium-chain disorders; electrocardiography (including 24 h monitoring) and echocardiography are done for most patients with long-chain and carnitine transporter deficiencies. Eye examination is done in all, and liver ultrasonography in some patients with long-chain 3-hydroxyacyl-coenzyme A dehydrogenase/tri-functional protein (LCHAD/TFP) deficiencies. Biochemical follow-up includes determination of free carnitine and acylcarnitines. Free carnitine is measured to monitor carnitine supplementation in patients with multiple acyl-coenzyme A dehydrogenase deficiency (MADD) and carnitine transporter deficiency (CTD) and to follow metabolic control and disclose deficiency states in other FAO disorders. We are evaluating long-chain acylcarnitines in patients with long-chain disorders; so far there does not seem to be any clear-cut benefit in following these levels. An erythrocyte fatty acid profile is done in patients with long-chain disorders to test for essential fatty acid and docosahexanoic acid (DHA) deficiencies. The measurement of creatine kinase is helpful in long-chain disorders. Ongoing follow-up and education of the patient is important throughout life to prevent disease morbidity or death from metabolic crises.

Can we clinically identify patients at risk of malignant transformation of skin tumors in Brooke-Spiegler syndrome?

Brooke-Spiegler syndrome (BSS) is a rare inherited autosomal dominant disease characterized by the development of multiple adnexal cutaneous neoplasms. BSS has been linked to mutations in CYLD gene, which is a tumor suppressor gene located on chromosome 16q12-q13. An increased risk of malignant transformation of adnexal cutaneous tumors in BSS patients has been reported. However, no reported genetic markers identify patients at risk of cutaneous malignancy. This study reviews published cases of BSS to investigate the role of clinical parameters as biomarkers of skin malignancy. A comprehensive review of the clinical aspects of BSS is based on 55 case reports. Our analysis revealed only age as a predictor of malignancy; however, this is also a general risk factor for development of malignancy and therefore of limited value as a screening tool. The study highlights the need for standardized clinical follow-up of patients.

Danish expanded newborn screening is a successful preventive public health programme.

INTRODUCTION: Newborn screening is a public health programme for early diagnosis of treatable diseases. METHODS: The subjects included were newborns born 2002-2019. Expanded newborn screening (eNBS) for metabolic diseases was introduced as a pilot project from 2002 to 2009, followed by routine screening with informed dissent. A total of 967,780 newborns were screened; 82,930 were unscreened. Furthermore, a historic cohort of clinically diagnosed children born in the 1992-2001 period was included. Children in the unscreened and historic cohorts were evaluated for the same diseases as were the screened children. Dried blood spot samples were collected locally and sent for screening analyses. We recorded newborns with true and false positive results as well as false negative results and their clinical signs at screening and at the last follow-up. RESULTS: A total of 603 samples were screen positive: 354 false positives and 249 true positives (222 newborns and 27 mothers). The positive predictive value (PPV) was 41% for the entire screening period; 62% for 2018. The false positive rate (FPR) was 0.036% overall; 0.024% for 2018. The overall prevalence of diseases was 1:3,900; in the historic cohort, the prevalence of the same diseases was 1:8,300; 7.3% had symptoms at the time of screening. At follow-up, 93% of the children had no clinically significant sequelae. Among 82,930 unscreened newborns, 27 (1:3,000) had eNBS panel diseases, some with severe manifestations. CONCLUSIONS: This update of eNBS in Denmark confirms that eNBS is a successful preventive public health programme. Early treatment in a latent phase of disease is effective and screening should be extended to other diseases not currently in the programme. FUNDING: The work was supported by grants from The Ronald McDonald Børnefond, Danmarks Sundhedsfond, Direktør Ib Henriksens Fond, Ragnhild Ibsens Legat til Medicinsk Forskning, Gerda og Aage Haenschs Fond, Dronning Louises Børnehospitals Forskningsfond, Læge Sofus Carl Emil Friis og Hustru Olga Doris Friis's Legat, Aase and Ejnar Danielsens Fond, Oda og Hans Svenningsens Fond, Fonden af 1870, Vanførefonden, Fonden til Lægevidenskabens Fremme and Danish Medical Research Council. TRIAL REGISTRATION: not relevant.

Phenotype and 244k array-CGH characterization of chromosome 13q deletions: an update of the phenotypic map of 13q21.1-qter.

Partial deletions of the long arm of chromosome 13 lead to variable phenotypes dependant on the size and position of the deleted region. In order to update the phenotypic map of chromosome 13q21.1-qter deletions, we applied 244k Agilent oligonucleotide-based array-CGH to determine the exact breakpoints in 14 patients with partial deletions of this region. Subsequently, we linked the genotype to the patient's phenotype. Using this approach, we were able to refine the smallest deletion region linked to short stature (13q31.3: 89.5-91.6 Mb), microcephaly (13q33.3-q34), cortical development malformations (13q33.1-qter), Dandy-Walker malformation (DWM) (13q32.2-q33.1), corpus callosum agenesis (CCA) (13q32.3-q33.1), meningocele/encephalocele (13q31.3-qter), DWM, CCA, and neural tube defects (NTDs) taken together (13q32.3-q33.1), ano-/microphthalmia (13q31.3-13qter), cleft lip/palate (13q31.3-13q33.1), lung hypoplasia (13q31.3-13q33.1), and thumb a-/hypoplasia (13q31.3-q33.1 and 13q33.3-q34). Based on observations of this study and previous reports we suggest a new entity, "distal limb anomalies association," linked to 13q31.3q33.1 segment. Most of the individuals with deletion of any part of 13q21qter showed surprisingly similar facial dysmorphic features, and thus, a "13q deletion facial appearance" was suggested. Prominent nasal columella was mapped between 13q31.3 and 13q33.3, and micrognathia between 13q21.33 and 13q31.1. The degree of mental delay did not display a particular phenotype-genotype correlation on chromosome 13. In contrast to previous reports of carriers of 13q32 band deletions as the most seriously affected patients, we present two such individuals with long-term survival, 28 and 2.5 years.

The impact of consanguinity on the frequency of inborn errors of metabolism.

Inborn errors of metabolism (IEM) are a heterogeneous group of genetic disorders present in all ethnic groups. We investigated the frequency of consanguinity among parents of newborns with IEM diagnosed by neonatal screening. Data were obtained from 15 years of expanded newborn screening for selected IEM with autosomal recessive mode of inheritance, a national screening program of newborns covering the period from 2002 until April 2017. Among the 838,675 newborns from Denmark, the Faroe Islands and Greenland, a total of 196 newborns had an IEM of whom 155 from Denmark were included in this study. These results were crosschecked against medical records. Information on consanguinity was extracted from medical records and telephone contact with the families. Among ethnic Danes, two cases of consanguinity were identified in 93 families (2.15%). Among ethnic minorities there were 20 cases of consanguinity among 33 families (60.6%). Consequently, consanguinity was 28.2 times more frequent among descendants of other geographic place of origin than Denmark. The frequency of consanguinity was conspicuously high among children of Pakistani, Afghan, Turkish and Arab origin (71.4%). The overall frequency of IEM was 25.5 times higher among children of Pakistani, Turkish, Afghan and Arab origin compared to ethnic Danish children (5.35:10,000 v 0.21:10,000). The frequency of IEM was 30-fold and 50-fold higher among Pakistanis (6.5:10,000) and Afghans (10.6:10,000), respectively, compared to ethnic Danish children. The data indicate a strong association between consanguinity and IEM. These figures could be useful to health professionals providing antenatal, pediatric, and clinical genetic services.

The impact of consanguinity on the frequency of inborn errors of metabolism.

INTRODUCTION: We investigated the frequency of con-sanguinity among the parents to newborns with inborn errors of metabolism (IEM) diagnosed by neonatal screening. METHODS: Data were obtained from 15 years of national newborn screening for selected IEM with autosomal recessive mode of inheritance. Among the 838,675 newborns from Denmark, The Faroe Islands and Greenland, a total of 196 newborns had an IEM of whom 155 from Denmark were included in this study. These results were crosschecked against medical records. Information on consanguinity was extracted from medical records and obtained through telephone contact with the families. RESULTS: Among ethnic Danes, two cases of consanguinity were identified among 93 families (2.15%). Among ethnic minorities, there were 20 cases of consanguinity among a total of 33 families (60.6%). Consequently, consanguinity was 28.2 times more frequent among descendants of other geographic places of origin than Denmark. The frequency of consanguinity was high among children of Pakistani, Afghan, Turkish and Arab origin (71.4%). The overall frequency of IEM was 25.5 times higher among children of these ethnic groups than among ethnic Danish children (5.35:10,000 versus 0.21:10,000). The frequency of IEM was 30-fold and 50-fold higher among Pakistanis (6.5:10,000) and Afghans (10.6:10,000), respectively, compared with ethnic Danish children. CONCLUSIONS: The data indicate a strong association between consanguinity and IEM. These figures may be useful to health professionals providing antenatal, paediatric and clinical genetic services. FUNDING: none. TRIAL REGISTRATION: not relevant.