Similar Dysmorphic Features Research Articles

Siblings with Imperforate anus and aplastic nasal alae: Johanson-Blizzard syndrome

Johanson-Blizzard syndrome is a rare genetic entity reported in medical literature resulting from mutations in UBR1 gene, affecting pancreas, craniofacial and urogenital development, causing significant morbidity and mortality. We report a neonate presenting with anorectal malformation requiring surgical intervention at birth, with similar surgeries being performed in two elder siblings. Surviving sibling of the proband neonate also has similar dysmorphic features of absent ala nasi, aplasia cutis of scalp along with pancreatic insufficiency, profound sensorineural hearing loss, pheno-type corresponding to Johanson-Blizzard syndrome. Syndromic diagnosis helps in screening for associated potential issues, which can intervened at early stages.

Erotomania and phenotypic continuum in a family frameshift variant of AUTS2: a case report and review

BackgroundPathogenic variants of the AUTS2 (Autism Susceptibility candidate 2) gene predispose to intellectual disability, autism spectrum disorder, attention deficit hyperactivity disorder, facial dysmorphism and short stature. This phenotype is therefore associated with neurocognitive disturbances and social cognition, indicating potential functional maladjustment in the affected subjects, and a potentially significant impact on quality of life. Although many isolated cases have been reported in the literature, to date no families have been described. This case reports on a family (three generations) with a frameshift variant in the AUTS2 gene.Case presentationThe proband is 13 years old with short stature, dysmorphic features, moderate intellectual disability and autism spectrum disorder. His mother is 49 years old and also has short stature and similar dysmorphic features. She does not have autism disorder but presents an erotomaniac delusion. Her cognitive performance is heterogeneous. The two aunts are also of short stature. The 50-year-old aunt has isolated social cognition disorders. The 45-year-old aunt has severe cognitive impairment and autism spectrum disorder. The molecular analysis of the three sisters and the proband shows the same AUTS2 heterozygous duplication leading to a frame shift expected to produce a premature stop codon, p.(Met593Tyrfs*85). Previously reported isolated cases revealed phenotypic and cognitive impairment variability. In this case report, these variabilities are present within the same family, presenting the same variant.ConclusionsThe possibility of a phenotypic spectrum within the same family highlights the need for joint psychiatry and genetics research.

Heterozygous ANKRD17 loss-of-function variants cause a syndrome with intellectual disability, speech delay, and dysmorphism

ANKRD17 is an ankyrin repeat-containing protein thought to play a role in cell cycle progression, whose ortholog in Drosophila functions in the Hippo pathway as a co-factor of Yorkie. Here, we delineate a neurodevelopmental disorder caused by de novo heterozygous ANKRD17 variants. The mutational spectrum of this cohort of 34 individuals from 32 families is highly suggestive of haploinsufficiency as the underlying mechanism of disease, with 21 truncating or essential splice site variants, 9 missense variants, 1 in-frame insertion-deletion, and 1 microdeletion (1.16 Mb). Consequently, our data indicate that loss of ANKRD17 is likely the main cause of phenotypes previously associated with large multi-gene chromosomal aberrations of the 4q13.3 region. Protein modeling suggests that most of the missense variants disrupt the stability of the ankyrin repeats through alteration of core structural residues. The major phenotypic characteristic of our cohort is a variable degree of developmental delay/intellectual disability, particularly affecting speech, while additional features include growth failure, feeding difficulties, non-specific MRI abnormalities, epilepsy and/or abnormal EEG, predisposition to recurrent infections (mostly bacterial), ophthalmological abnormalities, gait/balance disturbance, and joint hypermobility. Moreover, many individuals shared similar dysmorphic facial features. Analysis of single-cell RNA-seq data from the developing human telencephalon indicated ANKRD17 expression at multiple stages of neurogenesis, adding further evidence to the assertion that damaging ANKRD17 variants cause a neurodevelopmental disorder.

Rabson–Mendenhall Syndrome in a brother-sister pair in Kuwait: Diagnosis and 5 year follow up

AimTo report on Rabson–Mendenhall Syndrome (RMS) diagnosed in Kuwait. MethodsA toddler (18 months old) was referred with high plasma insulin and dysmorphic features suggestive of RMS including coarse facial features with globular nose, full lips and furrowed tongue. His skin was hyperkeratotic with hypertrichosis. His sister (aged 13.5 years) was diagnosed with diabetes at 9 years of age and treated with metformin and insulin. She presented with similar dysmorphic features, extensive acanthosis nigricans, dental abnormalities and bilateral nephrocalcinosis. The children were born to non-consanguineous parents. Blood samples were sent for genetic testing in a reference laboratory. ResultsBoth children were found to be homozygous for the p.Arg141Trp missense variant (p.Arg114Trp if numbered according to pro-receptor sequence) in the alpha subunit of the insulin receptor. ConclusionsThese cases demonstrate the importance of raising awareness among healthcare professionals to ensure rapid referral of patients with characteristic physical features of RMS and severe insulin resistance for genetic testing. Unfortunately, treatment of RMS patients remains a challenge with poor prognosis and short life expectancy usually caused by diabetes-related complications. Genetic testing confirms the diagnosis and allows informed genetic counseling of parents considering future pregnancies.

MN1 C-terminal truncation syndrome is a novel neurodevelopmental and craniofacial disorder with partial rhombencephalosynapsis.

MN1 encodes a transcriptional co-regulator without homology to other proteins, previously implicated in acute myeloid leukaemia and development of the palate. Large deletions encompassing MN1 have been reported in individuals with variable neurodevelopmental anomalies and non-specific facial features. We identified a cluster of de novo truncating mutations in MN1 in a cohort of 23 individuals with strikingly similar dysmorphic facial features, especially midface hypoplasia, and intellectual disability with severe expressive language delay. Imaging revealed an atypical form of rhombencephalosynapsis, a distinctive brain malformation characterized by partial or complete loss of the cerebellar vermis with fusion of the cerebellar hemispheres, in 8/10 individuals. Rhombencephalosynapsis has no previously known definitive genetic or environmental causes. Other frequent features included perisylvian polymicrogyria, abnormal posterior clinoid processes and persistent trigeminal artery. MN1 is encoded by only two exons. All mutations, including the recurrent variant p.Arg1295* observed in 8/21 probands, fall in the terminal exon or the extreme 3' region of exon 1, and are therefore predicted to result in escape from nonsense-mediated mRNA decay. This was confirmed in fibroblasts from three individuals. We propose that the condition described here, MN1 C-terminal truncation (MCTT) syndrome, is not due to MN1 haploinsufficiency but rather is the result of dominantly acting C-terminally truncated MN1 protein. Our data show that MN1 plays a critical role in human craniofacial and brain development, and opens the door to understanding the biological mechanisms underlying rhombencephalosynapsis.

Rare De Novo Missense Variants in RNA Helicase DDX6 Cause Intellectual Disability and Dysmorphic Features and Lead to P-Body Defects and RNA Dysregulation

The human RNA helicase DDX6 is an essential component of membrane-less organelles called processing bodies (PBs). PBs are involved in mRNA metabolic processes including translational repression via coordinated storage of mRNAs. Previous studies in human cell lines have implicated altered DDX6 in molecular and cellular dysfunction, but clinical consequences and pathogenesis in humans have yet to be described. Here, we report the identification of five rare de novo missense variants in DDX6 in probands presenting with intellectual disability, developmental delay, and similar dysmorphic features including telecanthus, epicanthus, arched eyebrows, and low-set ears. All five missense variants (p.His372Arg, p.Arg373Gln, p.Cys390Arg, p.Thr391Ile, and p.Thr391Pro) are located in two conserved motifs of the RecA-2 domain of DDX6 involved in RNA binding, helicase activity, and protein-partner binding. We use functional studies to demonstrate that the first variants identified (p.Arg373Gln and p.Cys390Arg) cause significant defects in PB assembly in primary fibroblast and model human cell lines. These variants' interactions with several protein partners were also disrupted in immunoprecipitation assays. Further investigation via complementation assays included the additional variants p.Thr391Ile and p.Thr391Pro, both of which, similarly to p.Arg373Gln and p.Cys390Arg, demonstrated significant defects in P-body assembly. Complementing these molecular findings, modeling of the variants on solved protein structures showed distinct spatial clustering near known protein binding regions. Collectively, our clinical and molecular data describe a neurodevelopmental syndrome associated with pathogenic missense variants in DDX6. Additionally, we suggest DDX6 join the DExD/H-box genes DDX3X and DHX30 in an emerging class of neurodevelopmental disorders involving RNA helicases.

A distinct neurodevelopmental syndrome with intellectual disability, autism spectrum disorder, characteristic facies, and macrocephaly is caused by defects in CHD8.

A decade ago, we described novel de novo submicroscopic deletions of chromosome 14q11.2 in three children with developmental delay, cognitive impairment, and similar dysmorphic features, including widely-spaced eyes, short nose with flat nasal bridge, long philtrum, prominent Cupid's bow of the upper lip, full lower lip, and auricular anomalies. We suggested that this constituted a new multiple congenital anomaly-intellectual disability syndrome due to defects in CHD8 and/or SUPT16H. The three patients in our original cohort were between 2 years and 3 years of age at the time. Here we present a fourth patient and clinical updates on our previous patients. To document the longitudinal course more fully, we integrate published reports of other patients and describe genotype-phenotype correlations among them. Children with the disorder present with developmental delay, intellectual disability, and/or autism spectrum disorder in addition to characteristic facies. Gastrointestinal and sleep problems are notable. The identification of multiple patients with the same genetic defect and characteristic clinical phenotype, confirms our suggestion that this is a syndromic disorder caused by haploinsufficiency or heterozygous loss of function of CHD8.

Phenotypic spectrum associated with SPECC1L pathogenic variants: new families and critical review of the nosology of Teebi, Opitz GBBB, and Baraitser-Winter syndromes

The SPECC1L protein plays a role in adherens junctions involved in cell adhesion, actin cytoskeleton organization, microtubule stabilization, spindle organization and cytokinesis. It modulates PI3K-AKT signaling and controls cranial neural crest cell delamination during facial morphogenesis. SPECC1L causative variants were first identified in individuals with oblique facial clefts. Recently, causative variants in SPECC1L were reported in a pedigree reported in 1988 as atypical Opitz GBBB syndrome. Six families with SPECC1L variants have been reported thus far. We report here eight further pedigrees with SPECC1L variants, including a three-generation family, and a further individual of a previously published family. We discuss the nosology of Teebi and GBBB, and the syndromes related to SPECC1L variants. Although the phenotype of individuals with SPECC1L mutations shows overlap with Opitz syndrome in its craniofacial anomalies, the canonical laryngeal malformations and male genital anomalies are not observed. Instead, individuals with SPECCL1 variants have branchial fistulae, omphalocele, diaphragmatic hernias, and uterus didelphis. We also point to the clinical overlap of SPECC1L syndrome with mild Baraitser-Winter craniofrontofacial syndrome: they share similar dysmorphic features (wide, short nose with a large tip, cleft lip and palate, blepharoptosis, retrognathia, and craniosynostosis), although intellectual disability, neuronal migration defect, and muscular problems remain largely specific to Baraitser-Winter syndrome. In conclusion, we suggest that patients with pathogenic variants in SPECC1L should not be described as “dominant (or type 2) Opitz GBBB syndrome”, and instead should be referred to as “SPECC1L syndrome” as both disorders show distinctive, non overlapping developmental anomalies beyond facial communalities.

Oral-Facial-Digital Syndrome Type II (Mohr Syndrome) in Palestine

Oral-facial-digital syndrome (OFDS) is a group of disorders characterized by oral cavity malformation, facial deformities and digits anomalies. There are at least 13 forms of OFDS, in which most of them have brain anomalies and different degrees of mental retardation. We have reported two cases with quite different dysmorphic features. The first case was a female and had small wide-spaced eyes, wide nose bridge, middle line cleft of upper lip, cleft hard palate, microglossia, micrognathia, polydactyly and syndactyly of the upper and lower limbs. Moreover, she had congenital hypotonia. Brain and abdominal ultrasound studies were normal. The baby's mother had a history of losing her first pregnancy resulted from intrauterine fetal death who was presented with similar dysmorphic features. The second case was a 4-year-old male who had dysmorphic features; Antimongoloid eye slant, prominent ears, broad nose bridge, high arched palate, cleft soft palate, lingual nodule, preaxial and posaxial polydactyly with syndactyly in both hands, bilateral bifid thumbs and bilateral clinodactyly. Feet had polydactyly with syndactyly, and bifid big toe shape. The first time, that two cases with characteristic features of oral facial digital syndrome type II to be diagnosed in two Palestinian siblings of different family with consanguineous marriage.

De Novo Mutations in PPP3CA Cause Severe Neurodevelopmental Disease with Seizures

Exome sequencing has readily enabled the discovery of the genetic mutations responsible for a wide range of diseases. This success has been particularly remarkable in the severe epilepsies and other neurodevelopmental diseases for which rare, often de novo, mutations play a significant role in disease risk. Despite significant progress, the high genetic heterogeneity of these disorders often requires large sample sizes to identify a critical mass of individuals with disease-causing mutations in a single gene. By pooling genetic findings across multiple studies, we have identified six individuals with severe developmental delay (6/6), refractory seizures (5/6), and similar dysmorphic features (3/6), each harboring a de novo mutation in PPP3CA. PPP3CA encodes the alpha isoform of a subunit of calcineurin. Calcineurin encodes a calcium- and calmodulin-dependent serine/threonine protein phosphatase that plays a role in a wide range of biological processes, including being a key regulator of synaptic vesicle recycling at nerve terminals. Five individuals with de novo PPP3CA mutations were identified among 4,760 trio probands with neurodevelopmental diseases; this is highly unlikely to occur by chance (p = 1.2× 10-8) given the size and mutability of the gene. Additionally, a sixth individual with a de novo mutation in PPP3CA was connected to this study through GeneMatcher. Based on these findings, we securely implicate PPP3CA in early-onset refractory epilepsy and further support the emerging role for synaptic dysregulation in epilepsy.

De Novo Mutations in CHAMP1 Cause Intellectual Disability with Severe Speech Impairment

CHAMP1 encodes a protein with a function in kinetochore-microtubule attachment and in the regulation of chromosome segregation, both of which are known to be important for neurodevelopment. By trio whole-exome sequencing, we have identified de novo deleterious mutations in CHAMP1 in five unrelated individuals affected by intellectual disability with severe speech impairment, motor developmental delay, muscular hypotonia, and similar dysmorphic features including short philtrum and a tented upper and everted lover lip. In addition to two frameshift and one nonsense mutations, we found an identical nonsense mutation, c.1192C>T (p.Arg398*), in two affected individuals. All mutations, if resulting in a stable protein, are predicted to lead to the loss of the functionally important zinc-finger domains in the C terminus of the protein, which regulate CHAMP1 localization to chromosomes and the mitotic spindle, thereby providing a mechanistic understanding for their pathogenicity. We thus establish deleterious de novo mutations in CHAMP1 as a cause of intellectual disability.

Haploinsufficiency of two histone modifier genes on 6p22.3, ATXN1 and JARID2, is associated with intellectual disability

BackgroundNineteen patients with deletions in chromosome 6p22-p24 have been published so far. The syndromic phenotype is varied, and includes intellectual disability, behavioural abnormalities, dysmorphic features and structural organ defects. Heterogeneous deletion breakpoints and sizes (1–17 Mb) and overlapping phenotypes have made the identification of the disease causing genes challenging. We suggest JARID2 and ATXN1, both harbored in 6p22.3, as disease causing genes.Methods and resultsWe describe five unrelated patients with de novo deletions (0.1-4.8 Mb in size) in chromosome 6p22.3-p24.1 detected by aCGH in a cohort of approximately 3600 patients ascertained for neurodevelopmental disorders. Two patients (Patients 4 and 5) carried non-overlapping deletions that were encompassed by the deletions of the remaining three patients (Patients 1–3), indicating the existence of two distinct dosage sensitive genes responsible for impaired cognitive function in 6p22.3 deletion-patients. The smallest region of overlap (SRO I) in Patients 1–4 (189 kb) included the genes JARID2 and DTNBP1, while SRO II in Patients 1–3 and 5 (116 kb) contained GMPR and ATXN1. Patients with deletion of SRO I manifested variable degrees of cognitive impairment, gait disturbance and distinct, similar facial dysmorphic features (prominent supraorbital ridges, deep set eyes, dark infraorbital circles and midface hypoplasia) that might be ascribed to the haploinsufficiency of JARID2. Patients with deletion of SRO II showed intellectual disability and behavioural abnormalities, likely to be caused by the deletion of ATXN1. Patients 1–3 presented with lower cognitive function than Patients 4 and 5, possibly due to the concomitant haploinsufficiency of both ATXN1 and JARID2. The chromatin modifier genes ATXN1 and JARID2 are likely candidates contributing to the clinical phenotype in 6p22-p24 deletion-patients. Both genes exert their effect on the Notch signalling pathway, which plays an important role in several developmental processes.ConclusionsPatients carrying JARID2 deletion manifested with cognitive impairment, gait disturbance and a characteristic facial appearance, whereas patients with deletion of ATXN1 seemed to be characterized by intellectual disability and behavioural abnormalities. Due to the characteristic facial appearance, JARID2 haploinsufficiency might represent a clinically recognizable neurodevelopmental syndrome.

Familial distal monosomy 3p26.3‐pter with trisomy 4q32.2‐qter, presenting with progressive ataxia, intellectual disability, and dysmorphic features

We present a boy diagnosed with partial 3p monosomy and partial 4q trisomy. The patient was 9 years of age with intellectual disability, dysmorphic features, and ataxia. A family history and medical evaluation showed that the father manifested similar facial dysmorphic features, intellectual disability, quadriparesis, and progressive cerebrospinal ataxia. The chromosomal aberration found in the proband was inherited from his father who was found to have a balanced reciprocal translocation of chromosomes 3p and 4q, which was in turn inherited from the paternal grandfather. The final cytogenetic diagnosis according to microarray was 46,XY,der(3)t(3;4)(p26.1;q32.2)arr 3p26.1(39,066-5,363,502)x1,4q32.2q35.2(162,555,236-191,173,881)x3. We describe the cytogenetic investigations that led to the identification of the breakpoints. In addition, we present an overview of the clinical features found in patients with partial 3p monosomies and partial 4q trisomies as reported in the literature.

9q22 Deletion - First Familial Case

BackgroundOnly 29 cases of constitutional 9q22 deletions have been published and all have been sporadic. Most associate with Gorlin syndrome or nevoid basal cell carcinoma syndrome (NBCCS, MIM #109400) due to haploinsufficiency of the PTCH1 gene (MIM *601309).Methods and ResultsWe report two mentally retarded female siblings and their cognitively normal father, all carrying a similar 5.3 Mb microdeletion at 9q22.2q22.32, detected by array CGH (244 K). The deletion does not involve the PTCH1 gene, but instead 30 other gene,s including the ROR2 gene (MIM *602337) which causing both brachydactyly type 1 (MIM #113000) and Robinow syndrome (MIM #268310), and the immunologically active SYK gene (MIM *600085). The deletion in the father was de novo and FISH analysis of blood lymphocytes did not suggest mosaicism. All three patients share similar mild dysmorphic features with downslanting palpebral fissures, narrow, high bridged nose with small nares, long, deeply grooved philtrum, ears with broad helix and uplifted lobuli, and small toenails. All have significant dysarthria and suffer from continuous middle ear and upper respiratory infections. The father also has a funnel chest and unilateral hypoplastic kidney but the daughters have no malformations.ConclusionsThis is the first report of a familial constitutional 9q22 deletion and the first deletion studied by array-CGH which does not involve the PTCH1 gene. The phenotype and penetrance are variable and the deletion found in the cognitively normal normal father poses a challenge in genetic counseling.

Hoffman syndrome: New patients, new insights

Hypogammaglobulinemia or agammaglobulinemia are major features of specific syndromes, including X-linked agammaglobulinemia and common variable immunodeficiency. However, the combination of hypogammaglobulinemia with specific dysmorphic features is less common, with only a few reported cases. One such report was a sporadic case of humoral immunodeficiency, facial dysmorphism, and limb anomalies in a young girl, later referred to as Hoffman syndrome. We report on a 7-year-old girl with almost complete loss of B cells, facial dysmorphism, and malformation of the limbs and genitalia, whose mother shows similar dysmorphic features with an attenuated version of the B-cell deficiency. We believe that all three cases described above represent the same condition. The features of the three affected individuals with Hoffman syndrome are reviewed. Further investigations in this recently recognized B-cell immunodeficiency syndrome are warranted.

Clinical and molecular characterization of individuals with recurrent genomic disorder at 10q22.3q23.2

The identification of genomic imbalances in young patients can affect medical management by allowing early intervention for developmental delay and by identifying patients at risk for unexpected medical complications. Using a 105K-feature oligonucleotide array, we identified a 7.25 Mb deletion at 10q22.3q23.2 in six unrelated patients. Deletions of this region have been described in individuals with cognitive and behavioral abnormalities, including autistic features, and may represent a recurring genetic syndrome. All four patients in this study for whom clinical information was available had mild dysmorphic features and three had developmental delay. Of note is the emerging clinical phenotype in these individuals with similar dysmorphic features such as macrocephaly, hypertelorism, and arachnodactyly, and neurodevelopmental delay that includes failure to thrive, hypotonia, and feeding difficulties in the neonatal period, and receptive and expressive language delay with global neurodevelopmental delay after the neonatal period. However, there is no pattern of abnormalities, craniofacial, behavioral, or otherwise, that would have aroused clinical suspicion of a specific syndrome. Finally, the patients' deletions encompass BMPR1A but not PTEN, and these patients may be at risk for colon cancer and should be referred for appropriate prophylactic care and surveillance. Of the two patients in this study who had colonoscopy following the array results, neither had polyps. Therefore, the magnitude of the increased risk for colon cancer is currently unknown.

Molecular and clinical characterization of patients with overlapping 10p deletions

Chromosome 10p terminal deletions have been associated with DiGeorge phenotype, and within the same genomic region haploinsufficiency of GATA3 causes the HDR syndrome (hypoparathyroidism, sensorineural deafness, renal dysplasia). We have performed detailed molecular analysis of four patients with partial overlapping 10p deletions by using FISH-mapping, array-CGH, and custom-designed high-resolution oligonucleotide array. All four patients had mental retardation and speech impairment and three of them showed variable signs of HDR syndrome. In addition, two patients had autistic behaviors and had similar dysmorphic features giving them a striking physical resemblance. A review of the literature identified 10 previously published cases with similar 10p deletions and reliable molecular or molecular cytogenetic mapping data. The combined information of present and previous cases suggests that partial deletions of 10p14-p15 represent a syndrome with a distinct and more severe phenotype than previously assumed. The main characteristics include severe mental retardation, language impairment, autistic behavior, and characteristic clinical features. A critical region involved in mental retardation and speech impairment is defined within 1.6 Mb in 10p15.3. In addition, deletion of 4.3 Mb within 10p14 is associated with autism and characteristic clinical findings.

Growth without Growth Hormone and Similar Dysmorphic Features in Three Patients with Sporadic Combined Pituitary Hormone Deficiencies

Background/Aims: Mutations in the HESX1 gene are associated with a broad spectrum of phenotypes: septo-optic dysplasia, midline defects, pituitary abnormalities with consequent hypopituitarism, isolated growth hormone (GH) deficiency or combined pituitary hormone deficiencies (CPHD). This study examined the prevalence of mutations in the HESX1 gene in patients with CPHD. Patients/Methods: Sixty patients with sporadic CPHD without septo-optic dysplasia were screened for mutations in HESX1. Results: Three patients were found to be heterozygous for the same Asn125Ser variant in the HESX1 gene. In all 3, panhypopituitarism was presented in the neonatal period, manifested by severe hypoglycemia and neonatal jaundice in 2 patients and respiratory distress in 1. Remarkable findings from physical examination included coarse face; prominent, large, low-set ears; and skeletal abnormalities. Magnetic resonance imaging, performed in 2 patients, revealed a hypoplastic anterior and ectopic posterior pituitary without other midline anomalies. Despite persistent GH deficiency and undetectable levels of insulin-like growth factor 1, all patients had normal linear growth along the 10–25th percentile without GH therapy. Conclusion: The present study expands the clinical picture of HESX1 mutations by demonstrating that patients heterozygous for Asn125Ser may have a severe endocrinologic and neuroradiologic phenotype and similar dysmorphic features appearing very early in life.

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.

Pigmentary Mosaicism, Subcortical Band Heterotopia, and Brain Cystic Lesions

A 10-year-old boy presented with a severe and diffuse mosaic skin hypopigmentation running (in narrow bands) along the lines of Blaschko associated with mosaic areas of alopecia, facial dysmorphism with midface hypoplasia, bilateral punctate cataract, microretrognathia, short neck, pectus excavatum, joint hypermobility, mild muscular hypotonia, generalized seizures, and mild mental retardation. Cranial magnetic resonance imaging revealed hypoplastic corpus callosum (primarily posterior), subcortical band heterotopia, and diffuse subcortical, periventricular cystic-like lesions. Similar dysmorphic features were observed in the child's mother, but with no imaging abnormalities. The facial phenotype coupled with the cysts in the brain was strongly reminiscent of the oculocerebrorenal Lowe syndrome. Full chromosome studies in the parents and the proband and mutation analysis on peripheral blood lymphocytes (and on skin cultured fibroblasts from affected and unaffected skin areas in the child) in the genes for subcortical band heterotopia (DCX (Xq22.3-q23)], lissencephaly (PAFAH1B1, alias LIS1, at 17p13.3), and oculocerebrorenal syndrome of Lowe (OCRL at Xq23-q24)] were unrevealing. This constellation of multiple congenital anomalies including skin hypopigmentation and eye, musculoskeletal, and nervous system abnormalities was sufficiently characterized to be regarded as a novel example of pigmentary mosaicism of the Ito type (i.e., hypomelanosis of Ito).