Porencephaly in a fetus and HANAC in her father: variable expression of COL4A1 mutation.

COL4A1-associated disorders encompass a wide range of hereditary vasculopathy, including porencephaly and HANAC (adult-onset hemorrhagic stroke with cerebral aneurysm and retinal arterial tortuosity, renal cysts, and thenar muscle cramp). It remains elusive whether or not porencephaly and HANAC are molecularly distinctive disorders due to different classes of mutations. We report on a girl with porencephaly and an episode of microangiopathic hemolysis in infancy and her father with HANAC, both of whom had a heterozygous missense mutation of COL4A1 (c.3715G>A, p.G1239R). The current observation implies phenotypic diversities of COL4A1 mutations.

1p34.3 deletion involving GRIK3: Further clinical implication of GRIK family glutamate receptors in the pathogenesis of developmental delay.

A growing body of evidence suggests an association between microdeletion/microduplication and schizophrenia/intellectual disability. Abnormal neurogenesis and neurotransmission have been implicated in the pathogenesis of these neuropsychiatric and neurodevelopmental disorders. The kainate/AMPA-type ionotropic glutamate receptor (GRIK = glutamate receptor, ionotropic, kainate) plays a critical role in synaptic potentiation, which is an essential process for learning and memory. Among the five known GRIK family members, haploinsufficiency of GRIK1, GRIK2, and GRIK4 are known to cause developmental delay, whereas the roles of GRIK3 and GRIK5 remain unknown. Herein, we report on a girl who presented with a severe developmental delay predominantly affecting her language and fine motor skills. She had a 2.6-Mb microdeletion in 1p34.3 involving GRIK3, which encodes a principal subunit of the kainate-type ionotropic glutamate receptor. Given its strong expression pattern in the central nervous system and the biological function of GRIK3 in presynaptic neurotransmission, the haploinsufficiency of GRIK3 is likely to be responsible for the severe developmental delay in the proposita. A review of genetic alterations and the phenotypic effects of all the GRIK family members support this hypothesis. The current observation of a microdeletion involving GRIK3, a kainate-type ionotropic glutamate receptor subunit, and the neurodevelopmental manifestation in the absence of major dysmorphism provides further clinical implication of the possible role of GRIK family glutamate receptors in the pathogenesis of developmental delay.

Multiple café au lait spots in familial patients with MAP2K2 mutation.

Recent advances in genetic diagnostic technologies have made the classic disease nosology highly complicated. This situation is exemplified by rasopathies, among which neurofibromatosis type 1 and Noonan syndrome represent prototypic entities. The former condition is characterized by multiple café au lait spots and neurofibromas, while the latter is characterized by distinct facial features, webbed neck, congenital heart disease, and a short stature. On rare occasions, the features of both neurofibromatosis and Noonan syndrome co-exist within an individual; such patients are diagnosed as having neurofibromatosis-Noonan syndrome. Here, we report familial patients with multiple café au lait spots and Noonan syndrome-like facial features. A mutation analysis unexpectedly revealed a mutation in MAP2K2 in both the propositus and his mother. The propositus fulfilled the diagnostic criteria for neurofibromatosis type 1, but his mother did not. Their phenotype was not consistent with that of cardio-facio-cutaneous syndrome, which is classically known to be associated with MAP2K2 mutations. The mother of the propositus had cervical cancer at the age of 23 years, consistent with the oncogenic tendency associated with rasopathies. The phenotypic combination of multiple café au lait spots and Noonan syndrome-like facial features suggested a diagnosis of neurofibromatosis-Noonan syndrome. Whether this condition represents a discrete disease entity or a variable expression of neurofibromatosis type 1 has long been debated. The present observation suggests that some perturbation in the RAS/MAPK signaling cascade results in multiple café au lait spots, a key diagnostic phenotype of rasopathies, although the exact mechanism remains to be elucidated.

Severe craniosynostosis with Noonan syndrome phenotype associated with SHOC2 mutation: clinical evidence of crosslink between FGFR and RAS signaling pathways.

Dysregulation in the RAS signaling cascade results in a family of malformation syndromes called RASopathies. Meanwhile, alterations in FGFR signaling cascade are responsible for various syndromic forms of craniosynostosis. In general, the phenotypic spectra of RASopathies and craniosynostosis syndromes do not overlap. Recently, however, mutations in ERF, a downstream molecule of the RAS signaling cascade, have been identified as a cause of complex craniosynostosis, suggesting that the RAS and FGFR signaling pathways can interact in the pathogenesis of malformation syndromes. Here, we document a boy with short stature, developmental delay, and severe craniosynostosis involving right coronal, bilateral lambdoid, and sagittal sutures with a de novo mutation in exon1 of SHOC2 (c.4A>G p.Ser2Gly). This observation further supports the existence of a crosslink between the RAS signaling cascade and craniosynostosis. In retrospect, the propositus had physical features suggestive of a dysregulated RAS signaling cascade, such as fetal pleural effusion, fetal hydrops, and atrial tachycardia. In addition to an abnormal cranial shape, which has been reported for this specific mutation, craniosynostosis might be a novel associated phenotype. In conclusion, the phenotypic combination of severe craniosynostosis and RASopathy features observed in the propositus suggests an interaction between the RAS and FGFR signaling cascades. Patients with craniosynostosis in combination with any RASopathy feature may require mutation screening for molecules in the FGFR-RAS signaling cascade.

A novel mutation in SOX3 polyalanine tract: a case of Kabuki syndrome with combined pituitary hormone deficiency harboring double mutations in MLL2 and SOX3.

INTRODUCTION: Both duplications encompassing SOX3 and loss-of function mutations in SOX3 have been reported in a minor portion of X-linked isolated growth hormone deficiency (GHD) or combined pituitary hormone deficiency (CPHD) patients with or without mental retardation. PATIENTS AND METHODS: We report a Japanese male patient with molecularly confirmed Kabuki syndrome who was found to have CPHD. We analyzed all coding exons and flanking introns of currently known nine genes responsible for CPHD by PCR-based sequencing. RESULTS: In this CPHD patient, we identified a novel hemizygous 21-base pair deletion, resulting in the loss of 7 alanine residues from polyalanine (PA) tracts of SOX3. The clinically and endocrinologically normal mother of the patient carried the same deletion in a heterozygous manner. In vitro experiments showed that the del 7A SOX3 had increased transactivation of the HESX1 promoter. CONCLUSION: Our study provides additional evidence that deletion in PA tracts of SOX3 is associated with hypopituitarism. Female carriers of SOX3 PA tract deletions will show a broad phenotypic spectrum, ranging from clinically normal to CPHD.

Severe congenital lipodystrophy and a progeroid appearance: Mutation in the penultimate exon of FBN1 causing a recognizable phenotype.

Recently, three marfanoid patients with congenital lipodystrophy and a neonatal progeroid appearance were reported. Although their phenotype was distinct from that of classic Marfan syndrome, they all had a truncating mutation in the penultimate exon, i.e., exon 64, of FBN1, the causative gene for Marfan syndrome. These patients might represent a new entity, but the exact phenotypic and genotypic spectrum remains unknown. Here, we report on a girl born prematurely who exhibited severe congenital lipodystrophy and a neonatal progeroid appearance. The patient exhibited a characteristic growth pattern consisting of an accelerated growth in height with a discrepant poor weight gain. She had a characteristic facial appearance with craniosynostosis. A mutation analysis identified c.8175_8182del8bp, p.Arg2726Glufs*9 in exon 64 of the FBN1 gene. A review of similar, recently reported patients revealed that the cardinal features of these patients include (1) congenital lipodystrophy, (2) premature birth with an accelerated linear growth disproportionate to the weight gain, and (3) a progeroid appearance with distinct facial features. Lines of molecular evidence suggested that this new progeroid syndrome represents a neomorphic phenotype caused by truncated transcripts with an extremely charged protein motif that escapes from nonsense-mediated mRNA decay, altering FBN1-TGF beta signaling, rather than representing the severe end of the hypomorphic phenotype of the FBN1-TGF beta disorder spectrum. We propose that this marfanoid entity comprised of congenital lipodystrophy, a neonatal progeroid appearance, and a peculiar growth profile and caused by rare mutations in the penultimate exon of FBN1, be newly referred to as marfanoid-progeroid syndrome.

Severe obstructive sleep apnea in Loeys-Dietz syndrome successfully treated using continuous positive airway pressure.

Loeys-Dietz syndrome is a recently recognized connective tissue disorder characterized by severe craniofacial and skeletal abnormalities as well as arterial tortuosity with aggressive aneurysm formation. Marfan syndrome, a classic connective tissue disorder, is known to be associated with a risk of obstructive sleep apnea, but sleep-related breathing disorders have not been previously documented in Loeys-Dietz syndrome. The propositus had the prototypic features of Loeys-Dietz syndrome with a de novo mutation in TGFBR2. He developed severe obstructive sleep apnea during his infancy. Continuous positive airway pressure was introduced at age 7 years and provided significant improvement in his nocturnal apnea and sleep apnea-related symptoms, such as enuresis. Marfan syndrome is known to be associated with a high risk of sleep apnea because of its characteristic craniofacial and connective tissue abnormalities. Similarly, the severe craniofacial abnormalities in Loeys-Dietz syndrome may predispose patients to severe obstructive sleep apnea, even at a very young age. Despite the severity of obstructive sleep apnea in the propositus, the administration of continuous positive airway pressure was highly effective in alleviating his symptoms. In summary, severe obstructive sleep apnea was successfully treated using continuous positive airway pressure in a patient with Loeys-Dietz syndrome. Careful evaluation and aggressive intervention for the alleviation of obstructive sleep apnea is warranted in Loeys-Dietz syndrome.

12q14 microdeletion syndrome and short stature with or without relative macrocephaly.

Patients with 12q14 microdeletion can present with short stature with or without relative macrocephaly. When associated with relative macrocephaly, the phenotype resembles Silver-Russell syndrome (SRS). Short stature is attributable to haploinsufficiency of HMGA2, but a patient with a deletion at the HMGA2 locus only did not have macrocephaly. Hence, the presence of a separate locus for a relative macrocephaly phenotype was suggested. Herein, we present a girl with a 12q14 microdeletion involving the HMGA2 locus who had short stature but did not have macrocephaly. Inclusion and exclusion mappings based on a quantitative review of the degree of relative macrocephaly and the extent of the deletions in previously reported patients with a 12q14 microdeletion demonstrated a presumptive interval for relative macrocephaly spanning a few megabases. These results confirm that a deletion spanning both HMGA2 and this presumptive interval locus would cause an SRS-like phenotype.

Microduplication of Xq24 and Hartsfield syndrome with holoprosencephaly, ectrodactyly, and clefting.

The combination of holoprosencephaly and ectrodactyly, also known as Hartsfield syndrome, represents a unique genetic entity. An X-linked recessive mode of transmission has been suggested for this condition based on the observation that male patients have preferentially been affected. Thus far, no candidate genes have been suggested on the X chromosome. We report a male patient with a full-blown Hartsfield syndrome phenotype who had microduplication at Xq24 involving four genes. He presented with bilateral ectrodactyly of the hands (both hands had four fingers with a deep gap between the 2nd and 3rd digits), cleft lip and palate, and a depressed nasal bridge. Magnetic resonance imaging of the brain revealed lobar holoprosencephaly. His G-banded karyotype was normal. Array comparative genomic hybridization (CGH) using the Agilent 244K Whole Human Genome CGH array revealed a microduplication at Xq24 of 210 kb. Parental testing revealed that the deletion was derived from the asymptomatic mother. Of the genes on the duplicated interval, the duplications of SLC25A43 and SLC25A5 appeared to be the most likely to explain the patient's phenotype. From a clinical standpoint, it is important to point out that the propositus, who performs relatively well with holoprosencephaly and has a developmental quotient around 70, has survived multiple life-threatening episodes of hypernatremia. Awareness of the risk of hypernatremia is of great importance for the anticipatory management of patients with ectrodactyly and an oral cleft, even in the absence of overt hypotelorism.

Branchial arch defects and 19p13.12 microdeletion: defining the critical region into a 0.8 M base interval.

We present a patient with preauricular tags, preauricular and branchial pits, stenosis of the external auditory canals, mild hearing loss, and mild developmental delay who had a de novo 19p13.12 submicroscopic deletion. The size of the deletion was 760-kb, extending from 15,300,338 to 16,064,271 (hg18; NCBI Build 36.1). Our finding supports the notion that 19p13.12 represents a unique microdeletion syndrome characterized by branchial arch defects and the concept of exclusion mapping indicates that the putative locus for the branchial arch development is included in the 0.8-Mb interval defined by the deletion in the presently reported patient.

Survival of a male mosaic for PORCN mutation with mild focal dermal hypoplasia phenotype.

We report a 46,XY boy with a mild focal dermal hypoplasia phenotype who had both wild-type and mutated copies of the PORCN gene and was, therefore, mosaic for the mutation. He had cutaneous syndactyly, hydronephrosis, and nail dystrophy. Small whitish depigmented spots, which were slightly depressed from the skin surface, were distributed linearly on the trunk and arms. Aside from these findings, streaks of brown-pigmented macules were seen on the dorsal aspect of the legs. Both the linear arrangement of the whitish spots and the streaks of pigmented macules followed the lines of Blaschko. The phenotype of the patient, who did not exhibit cribriform atrophy, telangiectasia or fat herniation, seemed to be much milder than that of typical female patients with focal dermal hypoplasia. Analysis of the genomic DNA extracted from the peripheral lymphocytes revealed a transition 129G>A within exon 1 of PORCN, which leads to a nonsense mutation W43X. The percentage of peripheral lymphocytes carrying a mutation was estimated to be 50% by the subcloning and sequencing of individual clones of the PCR product amplified across the mutation. This patient's case history provides further molecular evidence supporting the concept that "male focal dermal hypoplasia" does exist and that typical features such as telangiectasia and fat herniation are sometimes absent.

Microdeletion of the Down syndrome critical region at 21q22.

The concept of the Down syndrome critical region implies the existence of several dosage-sensitive genes that result in an abnormal phenotype when duplicated. Among the genes in the presumed Down syndrome critical region, DYRK1A and SIM2 are thought to be particularly important because of their critical roles in the development of the central nervous system in model organisms. Considering that regulatory imbalances resulting in an altered amount of expression from crucial target genes tend to produce phenotypic effects in both monosomics and trisomics, haploinsufficiency for the Down syndrome critical region is expected to be associated with an abnormal phenotype. We report on a patient with severe microcephaly, a developmental delay, hypospadias, and corneal opacity who had a microdeletion spanning the Down syndrome critical region, including DYRK1A and SIM2. He presented with intrauterine growth retardation, hypospadias, corneal clouding, arched eyebrows, upslanting and narrow palpebral fissures, bifid uvula, prominent nasal root, short columella, prominent central incisors, pegged shaped teeth, retrognathia, hypoplastic nipples, and severe developmental delay. His G-banded karyotype was normal, but array comparative genomic hybridization showed a de novo deletion of 3.97 Mb at chromosome 21q22. The extreme degree of microcephaly in this patient may be ascribed to the haploinsufficiency of DYRK1A, since brain size is severely reduced in heterozygotes for the Dyrk1a null mutation in mice.

Multiplex PCR/liquid chromatography assay for screening of subtelomeric rearrangements.

In idiopathic or nonspecific mental retardation, the overall rate of cryptic subtelomeric rearrangements is estimated to be about 5%. Development of cost-effective screening for subtelomeric deletions would help clinical geneticists to make specific diagnoses in children with idiopathic mental retardation. Current screening modalities include fluorescence in situ hybridization (FISH) using subtelomeric probes and PCR-based quantitative analyses. Reductions in the cost and turnaround time will make the complete screening of subtelomeric rearrangements more widely used in clinical settings. Recently, a versatile method, called the multiplex PCR/liquid chromatography assay (MP/LC), was developed to assess copy numbers in this assay. Multiple genomic regions are amplified using unlabeled primers, then separated by ion-pair reversed-phase high-performance liquid chromatography. In the present study, we developed an MP/LC-based subtelomeric screening system that involves 21 multiple reactions and validated the protocol by analyzing 16 publicly available cell lines with known cytogenetic abnormalities involving at least one subtelomere per patient. To confirm the validity of the MP/LC method, we analyzed these cell lines concurrently with array-based comparative genomic hybridization (array-CGH), which gives higher resolution than the conventional G-banding technique. Among those 16 samples, the results from MP/LC and array-CGH agreed with each other perfectly. In 2 of the 16 samples, MP/LC correctly revealed subtelomeric duplications that were detected by array-CGH but were undetected by conventional cytogenetics, demonstrating the sensitivity of the MP/LC assay. This system is expected to be useful for making specific diagnoses and in genetic counseling for children with idiopathic mental retardation, a sizable fraction of whom have subtelomeric rearrangements.

Screening for Alagille syndrome mutations in the JAG1 and NOTCH2 genes using denaturing high-performance liquid chromatography.

Mutations in the JAG1 gene and the NOTCH2 gene cause Alagille syndrome. At present, however, genetic testing of Alagille syndrome is not commonly applied in clinical settings because the currently available assays are technically and financially demanding, mainly because of the size of the genes. In the present study, we optimized the highly sensitive and specific mutation scanning method automated denaturing high-performance liquid chromatography (DHPLC) to analyze the entire coding region of JAG1 and NOTCH2. The coding region was amplified by 69 primer pairs, all of which have the same cycling conditions, aliquoted on a 96-well format PCR plate. In this manner, all the exons were simultaneously amplified using a single block in a thermal cycler. We then wrote a computer script to analyze each segment of JAG1 and NOTCH2 by DHPLC in a serial manner using conditions that were optimized for each amplicon. The implementation of this screening method for JAG1 and NOTCH2 will help medical geneticists confirm their clinical impressions and provide accurate genetic counseling to the patients with Alagille syndrome and their families.

EFNB1 mutation at the ephrin ligand-receptor dimerization interface in a patient with craniofrontonasal syndrome.

Craniofrontonasal syndrome (CFNS) is characterized by craniosynostosis, hypertelorism, a broad nasal tip and occasionally cleft lip and palate, and is caused by a mutation in the ephrin-B1 gene (EFNB1). The study of naturally occurring human EFNB1 mutations offers a unique opportunity to better define the critical portion within the ephrin domain that is essential for the function of EFNB1 protein in craniofacial development. Here, we report a CFNS patient with a novel EFNB1 missense mutation present at the interface between EFNB1 and its receptor proteins. The patient's facial features included hypertelorism, a broad nasal tip, brachycephaly, frontal bossing, facial asymmetry and esotropia. In addition, she had pectus carinatum, grooved nails on her thumb, an abnormal palmar crease pattern and a broad first toe. Her development was appropriate for her age. Direct sequencing of polymerase chain reaction products using an autosequencer revealed a heterozygous missense mutation, Ser118Ile. Ser118 is located in the G-H loop of the extracellular ephrin domain and is highly evolutionarily conserved among rodents, avians and fish. The mutation occurred de novo and was not present in 100 normal Japanese control subjects. Substitutions of the adjacent amino acid residue, Pro119, have been previously reported in three CFNS patients. Since the structure of EFNB1 is not yet available, the spatial locality of Ser118 was characterized using the protein structure of EFNB2. We deduced that Ser118 in EFNB1 resides at the major dimerization interface with Eph receptors and inferred that the Ser118Ile mutation may impede the protrusion of the G-H loop, thereby disturbing Eph-Ephrin signal transduction.