A Long-term Follow-up of a Late Diagnosed Patient with Temple Syndrome - a Case Report.

Temple syndrome (TS) is a rare imprinting disorder, caused by alterations in the critical imprinted region 14q32 of chromosome 14. It is characterized by pre- and postnatal growth retardation, truncal hypotonia and facial dysmorphism in the neonatal period. We report a 18-year-old girl with a late diagnosis presenting all typical signs and symptoms of Temple syndrome - small for gestational age at birth, feeding difficulties, muscle hypotonia and delayed developmental milestones, central precocious puberty, truncal obesity and reduced growth. The patient is the second reported in the literature with signs of clinical and biochemical hyperandrogenism and the first treated with Dehydrocortisone®, with a good response. The clinical diagnosis of this patient was achieved after a long-term follow up at a single center of rare endocrine diseases, and a molecular genetics diagnosis of complete hypomethylation of 14q32 chromosome imprinting center (DLK/GTL2) was recently established. Growth hormone (GH) treatment was not given and although precocious puberty was treated in line with standard protocols, patient's final height remained below the target range. Increased awareness of Temple syndrome and timely molecular diagnosis enables improvement of clinical care of these patients as well as prevention of inherent metabolic consequences.

Recent Advances in Imprinting Disorders.

Imprinting disorders (ImpDis) are a group of currently 12 congenital diseases with common underlying (epi)genetic etiologies and overlapping clinical features affecting growth, development and metabolism. In the last years it has emerged that ImpDis are characterized by the same types of mutations and epimutations, i.e. uniparental disomies, copy number variations, epimutations, and point mutations. Each ImpDis is associated with a specific imprinted locus, but the same imprinted region can be involved in different ImpDis. Additionally, even the same aberrant methylation patterns are observed in different phenotypes. As some ImpDis share clinical features, clinical diagnosis is difficult in some cases. The advances in molecular and clinical diagnosis of ImpDis help to circumvent these issues, and they are accompanied by an increasing understanding of the pathomechanism behind them. As these mechanisms have important roles for the etiology of other common conditions, the results in ImpDis research have a wider effect beyond the borders of ImpDis. For patients and their families, the growing knowledge contributes to a more directed genetic counseling of the families and personalized therapeutic approaches.

Prematurity and Genetic Testing for Neonatal Diabetes.

BACKGROUND: Hyperglycemia in premature infants is usually thought to reflect inadequate pancreatic development rather than monogenic neonatal diabetes. No studies, to our knowledge, have investigated the prevalence of monogenic forms of diabetes in preterm infants. METHODS: We studied 750 patients with diabetes diagnosed before 6 months of age. We compared the genetic etiology and clinical characteristics of 146 preterm patients born <37 weeks and compared them with 604 born ≥37 weeks. RESULTS: A genetic etiology was found in 97/146 (66%) preterm infants compared with 501/604 (83%) born ≥37weeks, P < .0001. Chromosome 6q24 imprinting abnormalities (27% vs 12%, P = .0001) and GATA6 mutations (9% vs 2%, P = .003) occurred more commonly in preterm than term infants while mutations in KCNJ11 were less common (21 vs 34%, P = .008). Preterm patients with an identified mutation were diagnosed later than those without an identified mutation (median [interquartile range] 35 [34 to 36] weeks vs 31 [28 to 36] weeks, P < .0001). No difference was seen in other clinical characteristics of preterm patients with and without an identified mutation including age of presentation, birth weight, and time to referral. CONCLUSIONS: Patients with neonatal diabetes due to a monogenic etiology can be born preterm, especially those with 6q24 abnormalities or GATA6 mutations. A genetic etiology is more likely in patients with less severe prematurity (>32 weeks). Prematurity should not prevent referral for genetic testing as 37% have a potassium channel mutation and as a result can get improved control by replacing insulin with sulphonylurea therapy.

Clinical and molecular characterization of the 20q11.2 microdeletion syndrome: six new patients.

Interstitial microdeletions of 20q chromosome are rare, only 17 patients have been reported in the literature to date. Among them, only six carried a proximal 20q11.21-q11.23 deletion, with a size ranging from 2.6 to 6.8 Mb. The existence of a 20q11.2 microdeletion syndrome has been proposed, based on five previously reported cases that displayed anomalies of the extremities, intellectual disability, feeding difficulties, craniofacial dysmorphism and variable malformations. To further characterize this syndrome, we report on six new patients with 20q11.2 microdeletions diagnosed by whole-genome array-based comparative genomic hybridization. These patient reports more precisely refined the phenotype and narrowed the minimal critical region involved in this syndrome. Careful clinical assessment confirms the distinctive clinical phenotype. The craniofacial dysmorphism consists of high forehead, frontal bossing, enophthalmos, and midface hypoplasia. We have identified a 1.62 megabase minimal critical region involved in this syndrome encompassing three genes­GDF5, EPB41L1, andSAMHD1­which are strong candidates for different aspects of the phenotype. These results support that 20q11.2 microdeletion syndrome is a new contiguous gene deletion syndrome with a recognizable phenotype.

Heterogeneity of the growth phenotype and birth size in acid-labile subunit (ALS) deficiency.

PURPOSE: The IGFALS gene encodes the acid-labile subunit (ALS) protein, which regulates circulating IGF-1. Human IGFALS mutations cause growth hormone insensitivity (GHI) associated with ALS, IGF-1 and IGFBP-3 deficiencies and mild to moderate postnatal growth impairment (height SDS -2 to -4). Prenatal growth impairment is not a recognised feature of this disorder, but heterozygous carriers may show an intermediate phenotype. METHODS: We report a family of five subjects, including three children born small for gestational age, who were investigated for IGFALS gene mutations. RESULTS: The proband, an 8.7 years female with pre- and postnatal growth failure (BW SDS -3.04, Ht SDS -3.86) and biochemical features of GHI, had a homozygous mutation of IGFALS, c.401T>A; p.L134Q. Her 6.1 years brother (BW SDS -2.11, Ht SDS -2.0) had the same homozygous IGFALS mutation. Both parents [adult height SDS -1.76 (father) and -1.82 (mother)] and her 2.7 years sister (BW SDS -2.60, Ht SDS -2.04) were heterozygous for the IGFALS mutation. CONCLUSION: Significant phenotypic heterogeneity was observed between family members, in particular varying degrees of prenatal growth retardation were present in the three siblings, which may have contributed to the variation in the postnatal growth phenotype.

Clinical presentation of 6q24 transient neonatal diabetes mellitus (6q24 TNDM) and genotype-phenotype correlation in an international cohort of patients.

AIMS/HYPOTHESIS: 6q24 transient neonatal diabetes mellitus (TNDM) is a rare form of diabetes presenting in the neonatal period that remits during infancy but, in a proportion of cases, recurs in later life. We aim to describe the clinical presentation of 6q24 TNDM in the largest worldwide cohort of patients with defined molecular aetiology, in particular seeking differences in presentation or clinical history between aetiological groups. METHODS: One-hundred and sixty-three patients with positively diagnosed 6q24 TNDM were ascertained from Europe, the Americas, Asia and Australia. Clinical data from referrals were recorded and stratified by the molecular aetiology of patients. RESULTS: 6q24 TNDM patients presented at a modal age of one day, with growth retardation and hyperglycaemia, irrespective of molecular aetiology. There was a positive correlation between age of presentation and gestational age, and a negative correlation between adjusted birthweight SD and age of remission. Congenital anomalies were significantly more frequent in patients with paternal uniparental disomy of chromosome 6 or hypomethylation of multiple imprinted loci defects than in those with 6q24 duplication or isolated hypomethylation defects. Patients with hypomethylation had an excess representation of assisted conception at 15%. CONCLUSIONS/INTERPRETATION: This, the largest case series of 6q24 TNDM published, refines and extends the clinical phenotype of the disorder and confirms its clinical divergence from other monogenic TNDM in addition to identifying previously unreported clinical differences between 6q24 subgroups.

Early-onset LBSL: how severe does it get?

AIM: Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL) is known as a relatively mild leukoencephalopathy. We investigated the occurrence of severe variants of LBSL with extensive brain magnetic resonance imaging (MRI) abnormalities. METHOD: MRIs of approximately 3,000 patients with an unknown leukoencephalopathy were retrospectively reviewed for extensive signal abnormalities of the cerebral and cerebellar white matter, posterior limb of the internal capsule, cerebellar peduncles, pyramids, and medial lemniscus. Clinical data were retrospectively collected. RESULTS: Eleven patients fulfilled the MRI criteria (six males); six had DARS2 mutations. Clinical and laboratory findings did not distinguish between patients with and without DARS2 mutations, but MRI did. Patients with DARS2 mutations more often had involvement of structures typically affected in LBSL, including decussatio of the medial lemniscus, anterior spinocerebellar tracts, and superior and inferior cerebellar peduncles. Also, involvement of the globus pallidus was associated with DARS2 mutations. Earliest disease onset was neonatal; earliest death at 20 months. INTERPRETATION: This study confirms the occurrence of early infantile, severe LBSL, extending the known phenotypic range of LBSL. Abnormality of specific brainstem tracts and cerebellar peduncles are MRI findings that point to the correct diagnosis.

Novel Tandem Duplication in Exon 1 of the SNURF/SNRPN Gene in a Child with Transient Excessive Eating Behaviour and Weight Gain.

A deletion in 15q11.2 involving the SNURF/SNRPN gene is the typical finding in patients with Prader-Willi syndrome. Apart from translocations disrupting this gene, no other mutation types have been described so far. We report a patient in whom a small duplication in exon 1 of the SNURF/SNRPN gene was diagnosed which is predicted to interrupt only SNURF expression. The patient was investigated due to overgrowth, increased appetite and developmental delay in childhood. This duplication was inherited from her father who carries the duplication on his paternal chromosome 15 and also had transient excessive eating behaviour as an adolescent. RNA studies showed that the duplication introduces a premature stop codon in SNURF.

Persistent Fetal Vasculature and Severe Protein C Deficiency.

Persistent fetal vasculature (PFV) is most often a condition of unknown cause. It represents persisting elements of fetal ocular vessels including the hyaloid arterial network. Protein C is a vitamin K-dependent serine protease, which regulates coagulation. Deficiency of protein C leads to a prothrombotic state. We report the case of a male infant born at 34 weeks gestation to non-consanguineous parents. Ophthalmic examination found bilateral PFV, microphthalmia and vitreoretinal dysplasia. He also suffered bilateral renal vein thrombosis and purpura fulminans and was diagnosed with severe protein C deficiency. Genetic analysis of the PROC gene revealed two separate pathogenic mutations, confirming compound heterozygote status. Both parents were found to be heterozygous. While ocular manifestations (commonly haemorrhages) are often seen in protein C-deficient patients, a search of the literature reveals very few recorded cases of PFV in severe protein C deficiency. We hypothesise that protein C deficiency was the cause of PFV in this patient. Intraocular thrombotic events in utero could affect the normal development of ocular vessels and lead to persistent elements of fetal vasculature in the eye. Consideration should be given to the possibility of protein C deficiency in patients presenting with PFV, particularly if bilateral.

Epigenotype-phenotype correlations in Silver-Russell syndrome.

BACKGROUND: Silver-Russell syndrome (SRS) is characterised by intrauterine growth restriction, poor postnatal growth, relative macrocephaly, triangular face and asymmetry. Maternal uniparental disomy (mUPD) of chromosome 7 and hypomethylation of the imprinting control region (ICR) 1 on chromosome 11p15 are found in 5-10% and up to 60% of patients with SRS, respectively. As many features are non-specific, diagnosis of SRS remains difficult. Studies of patients in whom the molecular diagnosis is confirmed therefore provide valuable clinical information on the condition. METHODS: A detailed, prospective study of 64 patients with mUPD7 (n=20) or ICR1 hypomethylation (n=44) was undertaken. RESULTS AND CONCLUSIONS: The considerable overlap in clinical phenotype makes it difficult to distinguish these two molecular subgroups reliably. ICR1 hypomethylation was more likely to be scored as 'classical' SRS. Asymmetry, fifth finger clinodactyly and congenital anomalies were more commonly seen with ICR1 hypomethylation, whereas learning difficulties and referral for speech therapy were more likely with mUPD7. Myoclonus-dystonia has been reported previously in one mUPD7 patient. The authors report mild movement disorders in three further cases. No correlation was found between clinical severity and level of ICR1 hypomethylation. Use of assisted reproductive technology in association with ICR1 hypomethylation seems increased compared with the general population. ICR1 hypomethylation was also observed in affected siblings, although recurrence risk remains low in the majority of cases. Overall, a wide range of severity was observed, particularly with ICR1 hypomethylation. A low threshold for investigation of patients with features suggestive, but not typical, of SRS is therefore recommended.

Further refinement of the critical minimal genetic region for the imprinting disorder 6q24 transient neonatal diabetes.

AIMS/HYPOTHESIS: Transient neonatal diabetes (TND) is associated with overexpression of genes within a critical region on 6q24. This study aims to refine the boundaries of this region to reduce the number of potential candidate genes for 6q24 TND. METHODS: Fifteen patients with transient neonatal diabetes and submicroscopic chromosome 6 duplications were investigated. The duplications were confirmed by microsatellite analysis and subsequently mapped using tiled chromosome 6 array Comparative Genomic Hybridisation (aCGH) and MLPA. Duplication boundaries were compared to identify the minimal shared region of duplication. These data were then used with available clinical data to identify associations between size of 6q24 duplication and severity of TND phenotype. RESULTS: Alignment of the minimal region of duplication to the human genome reduced the minimal TND critical region, formerly estimated at 440 kb, to 160-173 kb, revealing PLAGL1 (pleiomorphic adenoma gene-like 1) and HYMAI (imprinted in hydatidiform mole) to be the only genes wholly included therein. Additionally, the complete paternal duplication of a region containing the theoretical protein FAM164B was associated with the severe growth restriction observed in 6q24 duplication patients. CONCLUSIONS/INTERPRETATION: This study has significantly reduced the critical region associated with 6q24 TND. It has eliminated several previous TND candidate genes, leaving the overlapping imprinted genes PLAGL1 and HYMAI as the only remaining complete candidate genes for 6q24 TND. Moreover, these data provide the first evidence that an additional region, encompassing the theoretical protein FAM164B, may have a critical role in the growth restriction phenotype observed in many 6q24 TND patients.

Pancreatic hypoplasia presenting with neonatal diabetes mellitus in association with congenital heart defect and developmental delay.

Congenital pancreatic hypoplasia is a rare cause of neonatal diabetes. We report on a series of three patients with pancreatic agenesis and congenital heart defects. All had abdominal scan evidence of pancreatic agenesis. In addition, Patient 1 had a ventricular septal defect, patent ductus arteriosus and pulmonary artery stenosis; Patient 2 had a truncus arteriosus and Patient 3 had tetralogy of Fallot. Two of the three patients have developmental delay. All three patients were isolated cases within the family. Investigations included sequencing of GCK, ABCC8, IPF1, NEUROD1, PTF1A, HNF1B, INS, ISL1, NGN3, HHEX, G6PC2, TCF7L2, SOX4, FOXP3 (Patients 1 and 2), GATA4 and KCNJ11 genes (all three patients), but no mutations were found. Genetic investigation to exclude paternal UPD 6, methylation aberrations and duplications of 6q24 was also negative in all three. 22q11 deletion was excluded in all three patients. Array CGH in Patient (1) showed a approximately 250 kb, paternally inherited duplication of chromosome 12q [arr cgh 12q24.33 (B35:CHR12:131808577-132057649++) pat], not found in the other two patients. Permanent neonatal diabetes mellitus due to pancreatic hypoplasia with congenital heart defects has been reported before and may represent a distinct condition. We discuss this rare association and review previously reported literature.

Constitutional haploinsufficiency of tumor suppressor genes in mentally retarded patients with microdeletions in 17p13.1.

Chromosome microdeletions or duplications are detected in 10-20% of patients with mental impairment and normal karyotypes. A few cases have been reported of mental impairment with microdeletions comprising tumor suppressor genes. By array-CGH we detected 4 mentally impaired individuals carrying de novo microdeletions sharing an overlapping segment of approximately 180 kb in 17p13.1. This segment encompasses 18 genes, including 3 involved in cancer, namely KCTD11/REN, DLG4/PSD95, and GPS2. Furthermore, in 2 of the patients, the deletions also included TP53, the most frequently inactivated gene in human cancers. The 3 tumor suppressor genes KCTD11, DLG4, and GPS2, in addition to the GABARAP gene, have a known or suspected function in neuronal development and are candidates for causing mental impairment in our patients. Among our 4 patients with deletions in 17p13.1, 3 were part of a Brazilian cohort of 300 mentally retarded individuals, suggesting that this segment may be particularly prone to rearrangements and appears to be an important cause (approximately 1%) of mental retardation. Further, the constitutive deletion of tumor suppressor genes in these patients, particularly TP53, probably confers a significantly increased lifetime risk for cancer and warrants careful oncological surveillance of these patients. Constitutional chromosome deletions containing tumor suppressor genes in patients with mental impairment or congenital abnormalities may represent an important mechanism linking abnormal phenotypes with increased risks of cancer.

Phenotype and genotype in 17 patients with Goltz-Gorlin syndrome.

BACKGROUND: Goltz-Gorlin syndrome or focal dermal hypoplasia is a highly variable, X-linked dominant syndrome with abnormalities of ectodermal and mesodermal origin. In 2007, mutations in the PORCN gene were found to be causative in Goltz-Gorlin syndrome. METHOD: A series of 17 patients with Goltz-Gorlin syndrome is reported on, and their phenotype and genotype are described. RESULTS: In 14 patients (13 females and one male), a PORCN mutation was found. Mutations included nonsense (n = 5), frameshift (n = 2), aberrant splicing (n = 2) and missense (n = 5) mutations. No genotype-phenotype correlation was found. All patients with the classical features of the syndrome had a detectable mutation. In three females with atypical signs, no mutation was found. The male patient had classical features and showed mosaicism for a PORCN nonsense mutation in fibroblasts. Two affected sisters had a mutation not detectable in their parents, supporting germline mosaicism. Their father had undergone radiation for testicular cancer in the past. Two classically affected females had three severely affected female fetuses which all had midline thoracic and abdominal wall defects, resembling the pentalogy of Cantrell and the limb-body wall complex. Thoracic and abdominal wall defects were also present in two surviving patients. PORCN mutations can possibly cause pentalogy of Cantrell and limb-body wall complexes as well. Therefore, particularly in cases with limb defects, it seems useful to search for these. CONCLUSIONS: PORCN mutations can be found in all classically affected cases of Goltz-Gorlin syndrome, including males. Somatic and germline mosaicism occur. There is no evident genotype-phenotype correlation.

Isolated imprinting mutation of the DLK1/GTL2 locus associated with a clinical presentation of maternal uniparental disomy of chromosome 14.

The clinical phenotypes of maternal and paternal uniparental disomy of chromosome 14 (UPD14) are attributed to dysregulation of imprinted genes. A large candidate locus exists within 14q32, under the regulation of a paternally methylated intergenic differentially methylated region (IG-DMR). We present a patient with clinical features of maternal UPD14, including growth retardation, hypotonia, scoliosis, small hands and feet, and advanced puberty, who had loss of methylation of the IG-DMR with no evidence of maternal UPD14. This case provides support for the hypothesis that the maternal UPD14 phenotype is due to aberrant gene expression within the imprinted domain at 14q32.

Isolated imprinting mutation of the DLK1/GTL2 locus associated with a clinical presentation of maternal uniparental disomy of chromosome 14.

The clinical phenotypes of maternal and paternal uniparental disomy of chromosome 14 (UPD14) are attributed to dysregulation of imprinted genes. A large candidate locus exists within 14q32, under the regulation of a paternally methylated intergenic differentially methylated region (IG-DMR). We present a patient with clinical features of maternal UPD14, including growth retardation, hypotonia, scoliosis, small hands and feet, and advanced puberty, who had loss of methylation of the IG-DMR with no evidence of maternal UPD14. This case provides support for the hypothesis that the maternal UPD14 phenotype is due to aberrant gene expression within the imprinted domain at 14q32.

Cowden syndrome and Bannayan Riley Ruvalcaba syndrome represent one condition with variable expression and age-related penetrance: results of a clinical study of PTEN mutation carriers.

BACKGROUND: The most commonly reported phenotypes described in patients with PTEN mutations are Bannayan-Riley-Ruvalcaba syndrome (BRRS), with childhood onset, macrocephaly, lipomas and developmental delay, and Cowden Syndrome (CS), an adult-onset condition recognised by mucocutaneous signs, with a risk of cancers, in particular those of the thyroid and breast. It has been suggested that BRRS and CS are the same condition, but the literature continues to separate them and seek a genotype-phenotype correlation. OBJECTIVE: To study the clinical features of patients with known PTEN mutations and observe any genotype-phenotype correlation. METHODS: In total, 42 people (25 probands and 17 non-probands) from 26 families of all ages with PTEN mutations were recruited through the UK clinical genetics services. A full clinical history and examination were undertaken. RESULTS: We were unable to demonstrate a genotype-phenotype correlation. Furthermore, our findings in a 31-year-old woman with CS and an exon 1 deletion refutes previous reports that whole exon deletions are only found in patients with a BRRS phenotype. CONCLUSION: Careful phenotyping gives further support for the suggestion that BRRS and CS are actually one condition, presenting variably at different ages, as in other tumour-suppressor disorders such as neurofibromatosis type 1. This has important counselling implications, such as advice about cancer surveillance, for children diagnosed with BRRS.

A maternal hypomethylation syndrome presenting as transient neonatal diabetes mellitus.

The expression of imprinted genes is mediated by allele-specific epigenetic modification of genomic DNA and chromatin, including parent of origin-specific DNA methylation. Dysregulation of these genes causes a range of disorders affecting pre- and post-natal growth and neurological function. We investigated a cohort of 12 patients with transient neonatal diabetes whose disease was caused by loss of maternal methylation at the TNDM locus. We found that six of these patients showed a spectrum of methylation loss, mosaic with respect to the extent of the methylation loss, the tissues affected and the genetic loci involved. Five maternally methylated loci were affected, while one maternally methylated and two paternally methylated loci were spared. These patients had higher birth weight and were more phenotypically diverse than other TNDM patients with different aetiologies, presumably reflecting the influence of dysregulation of multiple imprinted genes. We propose the existence of a maternal hypomethylation syndrome, and therefore suggest that any patient with methylation loss at one maternally-methylated locus may also manifest methylation loss at other loci, potentially complicating or even confounding the clinical presentation.

Hereditary hyperferritinemia cataract syndrome: ocular, genetic, and biochemical findings.

PURPOSE: To describe the cataract morphology and genetic and biochemical findings in a four-generation family with hereditary hyperferritinemia cataract syndrome (HHCS). METHODS: Family members of the proband with HHCS were investigated. DNA sequencing was carried out to identify the iron responsive element (IRE) of the L-ferritin gene in affected and non-affected family members. Molecular modeling allowed prediction of the structure of the mutant IRE in affected cases. Serum ferritin and transferrin saturation were determined using standard methods. All family members underwent slit lamp examination by an ophthalmologist to document presence of cataract or lens status. Cataract morphology was documented where present. RESULTS: This family with HHCS had the genetic heterozygous mutation G32C in the IRE of the L-ferritin mRNA. Lens opacities were detectable in young members of the family, and morphology of cataracts was consistent with previous reports. Biochemical testing demonstrated high serum ferritin levels in affected individuals. CONCLUSIONS: The morphology of cataracts in HHCS seems to be similar in all cases. In the heterozygous G32C mutation, the age at onset of cataracts is very early. Greater awareness of this condition among ophthalmologists will lead to effective family counseling of those affected, by genetic testing or simple biochemical tests. Serum ferritin levels can be effectively used to screen for this condition in suspected families.