Myopathic mtDNA Depletion Syndrome Due to Mutation in TK2 Gene.

Whole-exome sequencing was used to identify the disease gene(s) in a Spanish girl with failure to thrive, muscle weakness, mild facial weakness, elevated creatine kinase, deficiency of mitochondrial complex III and depletion of mtDNA. With whole-exome sequencing data, it was possible to get the whole mtDNA sequencing and discard any pathogenic variant in this genome. The analysis of whole exome uncovered a homozygous pathogenic mutation in thymidine kinase 2 gene ( TK2; NM_004614.4:c.323 C>T, p.T108M). TK2 mutations have been identified mainly in patients with the myopathic form of mtDNA depletion syndromes. This patient presents an atypical TK2-related myopathic form of mtDNA depletion syndromes, because despite having a very low content of mtDNA (<20%), she presents a slower and less severe evolution of the disease. In conclusion, our data confirm the role of TK2 gene in mtDNA depletion syndromes and expanded the phenotypic spectrum.

Clinical and molecular characterization of five Spanish kindreds with X-linked adrenal hypoplasia congenita: atypical findings and a novel mutation in NR0B1.

BACKGROUND: X-linked adrenal hypoplasia congenita (AHC) is caused by NR0B1 (DAX1) gene mutations. Affected male children suffer from adrenal insufficiency, leading to a salt-wasting crisis in early infancy and hypogonadotropic hypogonadism in adulthood. OBJECTIVE: To characterize clinically and at the molecular level a cohort of Spanish patients with AHC. PATIENTS AND METHODS: Nine boys (from five families) with AHC were screened for NR0B1 mutations. Clinical and endocrine evaluations were recorded. RESULTS: NR0B1 gene mutations were found in all analyzed patients, one of them being novel (p.Gln305*). One patient presented with preserved hypothalamic-pituitary-gonadal axis. Salt-wasting episodes, delayed puberty, and hypogonadotropic hypogonadism were common, although no association was observed between AHC phenotype and genetic mutations. None of the patients has had descendants. CONCLUSIONS: AHC phenotype cannot be predicted based on genetic results as there is no definite genotype-phenotype relationship, including intrafamilial variability. Nevertheless, genetic testing for NR0B1 mutations is indicated if there is a suspicion of an X-linked adrenal insufficiency in order to proceed with the appropriate therapy and genetic counseling.

Delineation of the clinically recognizable 17q22 contiguous gene deletion syndrome in a patient carrying the smallest microdeletion known to date.

We describe a patient with a 1.34 Mb microdeletion at chromosome band 17q22, which is also present in his affected mother. To better delineate this microdeletion syndrome, we compare the clinical and molecular characteristics of 10 previously reported cases and our patient. Of these, the present patient has the smallest deletion which includes five genes: MMD, TMEM100, PCTP, ANKFN1, and NOG. We compare the clinical manifestations described in relation to NOG, since this is the only gene whose loss is shared by our patient and the other eight patients. Previously, the clinical patterns associated with NOG mutations have been included under the general term "NOG-related symphalangism spectrum disorder (NOG-SSD)." Based on our analyses, and considering that there is a clinical correlation observed in cases with a "17q22 microdeletion including NOG" of which the main characteristics can be contributed to loss of this gene, we propose that the clinical patterns observed in these patients should be named as NOG-spectrum disorder-contiguous gene syndrome (NOGSD-CGS). This designation is important for clinicians because when a patient has defects concordant with alterations of NOG but also presents other anomalies not related to this gene, they would be able to suspect the existence of a microdeletion affecting 17q22, therefore, allowing an early diagnosis. This will also enable the clinician to provide the family with adequate information about the prognosis and the risk of reoccurrence in future potential offspring.

Mutations in PRPS1 causing syndromic or nonsyndromic hearing impairment: intrafamilial phenotypic variation complicates genetic counseling.

BACKGROUND: PRPS1 encodes isoform I of phosphoribosylpyrophosphate synthetase (PRS-I), a key enzyme in nucleotide biosynthesis. Different missense mutations in PRPS1 cause a variety of disorders that include PRS-I superactivity, nonsyndromic sensorineural hearing impairment, Charcot-Marie-Tooth disease, and Arts syndrome. It has been proposed that each mutation would result in a specific phenotype, depending on its effects on the structure and function of the enzyme. METHODS: Thirteen Spanish unrelated families segregating X-linked hearing impairment were screened for PRPS1 mutations by Sanger sequencing. In two positive pedigrees, segregation of mutations was studied, and clinical data from affected subjects were compared. RESULTS: We report two novel missense mutations in PRPS1, p.Ile275Thr and p.Gly306Glu, which were found in the propositi of two unrelated Spanish families, both subjects presenting with nonsyndromic hearing impairment. Further investigation revealed syndromic features in other hemizygous carriers from one of the pedigrees. Sequencing of genes that are functionally related to PRPS1 did not reveal any candidate variant that might act as a phenotype modifier. CONCLUSION: This case of intrafamilial phenotypic variation associated with a single PRPS1 mutation complicates the genotype-phenotype correlations, which makes genetic counseling of mutation carriers difficult because of the wide spectrum of severity of the associated disorders.

Exome sequencing identifies a novel mutation in PIK3R1 as the cause of SHORT syndrome.

BACKGROUND: SHORT syndrome is a rare autosomal dominant condition whose name is the acronym of short stature, hyperextensibility of joints, ocular depression, Rieger anomaly and teething delay (MIM 269880). Additionally, the patients usually present a low birth weight and height, lipodystrophy, delayed bone age, hernias, low body mass index and a progeroid appearance. CASE PRESENTATION: In this study, we used whole-exome sequencing approaches in two patients with clinical features of SHORT syndrome. We report the finding of a novel mutation in PIK3R1 (c.1929_1933delTGGCA; p.Asp643Aspfs*8), as well as a recurrent mutation c.1945C > T (p.Arg649Trp) in this gene. CONCLUSIONS: We found a novel frameshift mutation in PIK3R1 (c.1929_1933delTGGCA; p.Asp643Aspfs*8) which consists of a deletion right before the site of substrate recognition. As a consequence, the protein lacks the position that interacts with the phosphotyrosine residue of the substrate, resulting in the development of SHORT syndrome.

A unique case of a discontinuous duplication 3q26.1-3q28 resulting from a segregation error of a maternal complex chromosomal rearrangement involving an insertion and an inversion.

Until now, few cases of partial trisomy of 3q due to segregation error of parental balanced translocation and segregation of a duplicated deficient product resulting from parental pericentric inversion have been reported so far. Only five cases of chromosomal insertion malsegregation involving 3q region are available yet, thus making it relatively rare. In this case report, we are presenting a unique case of discontinuous partial trisomy of 3q26.1-q28 region which resulted from a segregation error of two insertions involving 3q26.1 to 3q27.3 and 3q28 regions with ~21Mb and ~2Mb sizes, respectively. The maternally inherited insertion was cytogenetically characterized as der(8)(8pter→8p22::3q26→3q27.3::3q28→3q28::8p22→8qter) and the patient's major clinical features involved Dandy Walker malformation, sub-aortic ventricular septal defect, upslanting palpebral fissures, clinodactyly, hirsutism, and prominent forehead. Besides, a review of the literature involving cases with similar chromosomal imbalances and cases with "3q-duplication syndrome" is also provided.

Haploinsufficiency of BMP4 gene may be the underlying cause of Frías syndrome.

In 2005, we reported on a family as having Frías syndrome (OMIM: 609640), with four affected members displaying a pattern of congenital defects nearly identical to those observed in a mother and son described by Frias [Frías et al. (1975). Birth Defects Orig Artic Ser 11:30-33]. These defects included growth deficiency, facial anomalies, and hand and foot alterations. We had the opportunity to study this family again due to the birth of another affected girl, who presented with similar facial characteristics to those of her elder half-sister and the rest of affected relatives, which consisted of mild exophthalmia, bilateral palpebral ptosis, downslanting palpebral fissures, and hypertelorism. We performed array-CGH, which identified an identical interstitial deletion of chromosome 14q22.1-q22.3 in the mother and two daughters. The deletion is 4.06 Mb in length and includes the BMP4 gene, a member of the bone morphogenetic protein (BMP) family of secreted proteins. A review of the literature showed that deletions or mutations of this gene underlie congenital defects affecting brain, eye, teeth, and digit development. Although the clinical manifestations of the current family correlate with the defects observed in patients having either 14q22-q23 deletions or mutations of BMP4, they show a milder phenotype. In order to understand the clinical variability, we evaluated the already known functional characteristics of the BMP gene members. This gene family plays an important role during early embryogenesis, and the complex synergistic functions and redundancies of the BMPs led us to conclude that haploinsufficiency of BMP4 is likely to be responsible for the clinical expression of Frías syndrome.

Neonatal lupus erythematosus mimicking extensive capillary malformation.

Neonatal lupus erythematosus is an uncommon transplacentally acquired autoimmune disorder. We report a 7-month-old boy with cutaneous involvement of neonatal lupus erythematosus mimicking an extensive capillary malformation.

A novel mutation in the IRF6 gene associated with facial asymmetry in a family affected with Van der Woude syndrome.

This report describes a novel missense mutation in the interferon regulation factor 6 (IRF6) gene associated to facial asymmetry. This new feature widens the phenotype spectrum of Van der Woude syndrome (VWS).

Neonatal Lupus Erythematosus Mimicking Extensive Capillary Malformation.

Neonatal lupus erythematosus is an uncommon transplacentally acquired autoimmune disorder. We report a 7-month-old boy with cutaneous involvement of neonatal lupus erythematosus mimicking an extensive capillary malformation.

Evolutionary analyses of entire genomes do not support the association of mtDNA mutations with Ras/MAPK pathway syndromes.

BACKGROUND: There are several known autosomal genes responsible for Ras/MAPK pathway syndromes, including Noonan syndrome (NS) and related disorders (such as LEOPARD, neurofibromatosis type 1), although mutations of these genes do not explain all cases. Due to the important role played by the mitochondrion in the energetic metabolism of cardiac muscle, it was recently proposed that variation in the mitochondrial DNA (mtDNA) genome could be a risk factor in the Noonan phenotype and in hypertrophic cardiomyopathy (HCM), which is a common clinical feature in Ras/MAPK pathway syndromes. In order to test these hypotheses, we sequenced entire mtDNA genomes in the largest series of patients suffering from Ras/MAPK pathway syndromes analyzed to date (n = 45), most of them classified as NS patients (n = 42). METHODS/PRINCIPAL FINDINGS: The results indicate that the observed mtDNA lineages were mostly of European ancestry, reproducing in a nutshell the expected haplogroup (hg) patterns of a typical Iberian dataset (including hgs H, T, J, and U). Three new branches of the mtDNA phylogeny (H1j1, U5b1e, and L2a5) are described for the first time, but none of these are likely to be related to NS or Ras/MAPK pathway syndromes when observed under an evolutionary perspective. Patterns of variation in tRNA and protein genes, as well as redundant, private and heteroplasmic variants, in the mtDNA genomes of patients were as expected when compared with the patterns inferred from a worldwide mtDNA phylogeny based on more than 8700 entire genomes. Moreover, most of the mtDNA variants found in patients had already been reported in healthy individuals and constitute common polymorphisms in human population groups. CONCLUSIONS/SIGNIFICANCE: As a whole, the observed mtDNA genome variation in the NS patients was difficult to reconcile with previous findings that indicated a pathogenic role of mtDNA variants in NS.

Four small supernumerary marker chromosomes derived from chromosomes 6, 8, 11 and 12 in a patient with minimal clinical abnormalities: a case report.

INTRODUCTION: Small supernumerary marker chromosomes are still a problem in cytogenetic diagnostic and genetic counseling. This holds especially true for the rare cases with multiple small supernumerary marker chromosomes. Most such cases are reported to be clinically severely affected due to the chromosomal imbalances induced by the presence of small supernumerary marker chromosomes. Here we report the first case of a patient having four different small supernumerary marker chromosomes which, apart from slight developmental retardation in youth and non-malignant hyperpigmentation, presented no other clinical signs. CASE PRESENTATION: Our patient was a 30-year-old Caucasian man, delivered by caesarean section because of macrosomy. At birth he presented with bilateral cryptorchidism but no other birth defects. At age of around two years he showed psychomotor delay and a bilateral convergent strabismus. Later he had slight learning difficulties, with normal social behavior and now lives an independent life as an adult. Apart from hypogenitalism, he has multiple hyperpigmented nevi all over his body, short feet with pes cavus and claw toes. At age of 30 years, cytogenetic and molecular cytogenetic analysis revealed a karyotype of 50,XY,+min(6)(:p11.1-> q11.1:),+min(8)(:p11.1->q11.1:),+min(11)(:p11.11->q11:),+min(12)(:p11.2~12->q10:), leading overall to a small partial trisomy in 12p11.1~12.1. CONCLUSIONS: Including this case, four single case reports are available in the literature with a karyotype 50,XN,+4mar. For prenatally detected multiple small supernumerary marker chromosomes in particular we learn from this case that such a cytogenetic condition may be correlated with a positive clinical outcome.

[CHARGE syndrome]. / El síndrome CHARGE.

The characteristic phenotype of CHARGE syndrome includes: coloboma, congenital heart defect, choanal atresia, retarded growth and development, genital abnormalities, ear anomalies with or without hearing loss, which give the name (an acronym) to this condition. The molecular cause in 60% of the cases are mutations in the chromodomain helicase DNAbinding protein gene (CHD7), with an estimated frequency of 1 in 10,000 live born infants. We describe 3, not related patients with a clinical diagnosis of CHARGE syndrome and each of them with a different mutation in the CHD7 gene sequence.

El síndrome CHARGE / CHARGE syndrome

El síndrome CHARGE debe su nombre a un acrónimo definido por varios defectos congénitos: coloboma, cardiopatía (heart), atresia de coanas, retraso psicomotor y del crecimiento, genitales anómalos, malformaciones auriculares (ear) y/o sordera. Su causa más frecuente es una mutación del gen de la proteína de unión al cromodominio de la ADN helicasa (CHD7) identificada hasta en un 60 por ciento de los casos y su frecuencia se establece en torno a 1/10.000 nacidos vivos. Presentamos 3 pacientes no relacionados, identificados clínicamente y con distinta mutación en el gen CHD7.

[Prevalence of neural tube defects in Asturias (Spain): impact of prenatal diagnosis]. / Frecuencia de los defectos del tubo neural en Asturias: impacto del diagnóstico prenatal.

OBJECTIVE: To describe the frequency and prevalence trend for neural tube defects (NTD) (anencephaly, spina bifida and encephalocele) in Asturias (Spain), as well as the impact of prenatal diagnosis programs. METHODS: All cases of NTD in births and induced abortions were studied, using data from the Registry of Congenital Defects of Asturias for 1990-2004. Total and birth prevalence rates were calculated. RESULTS: The prevalence of NTD for 1990-2004 was 12.2 per 10,000 births (5.9 anencephaly, 5.0 spina bifida and 1.3 encephalocele) and showed a slightly decreasing trend due to a significant decline in spina bifida prevalence. The prevalence of anencephaly and encephalocele remained stable. The percentage of induced abortions after prenatal diagnosis among all NTD was 88% (anencephaly 96.7%, spina bifida 80% and encephalocele 84.6%), leading to a very low birth prevalence (1.4 per 10,000) for the entire period. CONCLUSIONS: The total prevalence of spina bifida has decreased in the last 15 years in Asturias. Secondary prevention through prenatal diagnosis and interruption of affected pregnancies have resulted in a marked decrease in NTD at birth. The recommendation of periconceptional use of folic acid seems not to have achieved the desired effect.

[Prevalence and secular trend of Down syndrome in Asturias (Spain), 1990-2004]. / Frecuencia del síndrome de Down en Asturias y tendencia temporal, 1990-2004.

BACKGROUND AND OBJECTIVE: Down syndrome (DS) is the most frequent chromosomal abnormality and bears a severe associated morbidity. Our goal was to describe trends in the prevalence of DS in Asturias (Spain). MATERIAL AND METHODS: Data from the Registry of Congenital Defects were analyzed, including births and induced abortions, between 1990 and 2004. RESULTS: Out of a total 103 452 births, 356 chromosomal anomalies had been registered (176 births and 180 induced abortions) and there were 210 DS (119 live births, two stillbirths and 89 induced abortions). Total prevalence assessment showed an important upward trend over time in both cases. The prevalence of total chromosomal abnormalities increased from 22 cases per 10 000 births in 1990 to 48,6 in 2004 and the DS prevalence increased from 13 to 29,1. Furthermore, 63% of DS births presented one or more associated defects, cardiac and digestive tract defects being the most frequent. CONCLUSIONS: Changes in maternal age and prenatal screening have influenced DS prevalence and trends.

[Prevalence and secular trend of congenital defects in Asturias, Spain. The need for clinical-epidemiological surveillance]. / Frecuencia y tendencia temporal de los defectos congénitos en Asturias. La necesidad de la vigilancia clinicoepidemiológica.

OBJECTIVE: Congenital defects remain the second cause of perinatal and infant death and the third cause between the second and fifth years of life in Asturias. These anomalies generate substantial morbidity. The aim of the present study was to describe the population-based frequency of congenital defects in Asturias and their forms of presentation. METHODS: Data from the population-based Registry of Congenital Defects of Asturias for 1990-2004 were analyzed. The data related to live births, stillbirths and induced abortions after prenatal diagnosis and are presented as birth prevalence and total prevalence (including induced abortions). RESULTS: The total number of births was 103,452 and there were 3,035 cases of congenital defects, representing a total prevalence of 2.9 cases per 100 births and a birth prevalence of 2.5%. These figures showed a tendency to increase throughout the study period. A total of 2,516 (82.9%) cases were live births, 46 (1.5%) were stillbirths and 473 (15.6%) were induced abortions. Prenatal diagnosis increased throughout the period. Sixtythree percent of total cases showed an isolated defect, 17% a recognized syndrome and the remaining 20% had multiple malformations without a syndromic pattern. The most frequent and severe defects registered were neural tube defects (12.2 per 10,000 births), chromosomal abnormalities (34.4 per 10,000), and cardiac defects (75.2 per 10,000). CONCLUSIONS: The 15-year experience of the Registry of Congenital Defects of Asturias reveals the utility of this type of database to evaluate prenatal screening programs, plan the resources needed in affected pregnant women and infants, and perform epidemiological surveillance of congenital defects in relation to environmental risks, drug exposure and assisted reproduction techniques.

Sensorineural deafness, abnormal genitalia, synostosis of metacarpals and metatarsals 4 and 5, and mental retardation: description of a second patient and exclusion of HOXD13.

In 1988 Pfeiffer and Kapferer reported on a patient with sensorineural deafness, psychomotor delay, hypospadias, cerebral manifestations, and bilateral synostosis of the 4th and 5th metacarpals and metatarsals. Synostosis of the 4th and 5th metacarpals and metatarsals is a very rare defect that has been described as an isolated Mendelian defect, as part of multiple congenital anomaly (MCA) patterns, and in different syndromes. Among a total of 2,023,155 liveborn infants in the Spanish Collaborative Study of Congenital Malformations (ECEMC), we observed only two cases with this type of metacarpal fusion, for a frequency of 1/1,011,577. One had the isolated defect, and the other one that we are describing here, had an MCA pattern similar to that described by Pfeiffer and Kapferer [1988]. We tested HOXD13 but did not find any mutations in exons and intron-exon boundaries. To our knowledge this case is the second one reported with this syndrome.

Renal involvement in Down syndrome.

Kidney disease has not been considered a frequent complication in Down syndrome (DS) patients; a variety of urological abnormalities and glomerulopathies have been reported in this population, and some DS patients develop chronic renal failure (CRF). The aim of this study was to improve the understanding of renal disease in patients with DS, focusing on the incidence and range of kidney and urological abnormalities in a population of DS patients. A cross-sectional study was carried out in DS patients referred from a pediatric genetics unit of a tertiary care center. Medical records were reviewed. A 24-h urine specimen and a blood sample were obtained. Fractional excretion of sodium and potassium, tubular reabsorption of phosphate, urinary excretion of calcium, magnesium, uric acid, creatinine clearance and proteinuria were determined. Ultrasound was performed to evaluate the kidneys and the urinary tract. Laboratory data were reviewed for any possible renal disorder. Sixty-nine patients, aged 12 months to 24 years, were recruited. Pathological findings included three cases of voiding disturbances and a case of hypertension in a 7-year old girl. Eight patients (11.6%) had hyperuricemia without gout. Eighteen patients (24.2%) had hyperuricosuria. Urinalysis revealed three cases of mild proteinuria and two patients with microscopic hematuria. Minor radiological abnormalities were found in five patients (7.3%). Three patients (4.5%) had CRF. Renal disease in patients with DS is not as rare as previously thought, although the majority of findings are of minor relevance. According to the variety of pathologies, and in order to detect early irreversible renal injury, it seems quite reasonable to perform regular monitoring of renal function in these patients.