Contiguous gene syndrome due to an interstitial deletion in Xp22.3 in a boy with ichthyosis, chondrodysplasia punctata, mental retardation and ADHD

Microdeletions of Xp22.3 can result in contiguous gene syndromes, showing the variable association of apparently unrelated clinical manifestations such as ichthyosis, chondrodysplasia punctata, hypogonadotropic hypogonadism, anosmia, ocular albinism, short stature and mental retardation. We report on a boy with ichthyosis, dysmorphic features and mental retardation with ADHD. The patient was born at term after a pregnancy complicated by threatened abortion; decreased fetal movements and low estriol serum levels were reported during the last trimester. The boy was referred to us at the age of 13 years. He presented with aggressive and hyperactive behavior. He had dry hair, a flat face, bilateral lens opacities, a small nose with hypoplastic tip, alae nasi and nares, a high-arched palate with a very small cleft, mixed dentition with 7 unerupted permanent teeth, left sensorineural and right mixed hearing loss with a calcified plaque of the tympanic membrane, marked shortness of terminal phalanges of hands and feet, ichthyosis of trunk and limbs. The genomic interval between AFM248th5 and KAL1 was investigated. PCR analysis showed a deletion in Xp22.3, with the distal breakpoint between the marker AFM248th5 and PABX and the proximal one between DXS278 and KAL1. Array-CGH and FISH analysis confirmed the interstitial deletion (of about 5.5 Mb) and refined the breakpoints. We discuss the phenotype of our patient in relationship to the deleted segment and the possibility of mental retardation and ADHD genes in the region.     

Trisomy of chromosome 16p13.3 due to an unbalanced insertional translocation into chromosome 22p13

A dysmorphic boy with severe mental retardation was found on array CGH to have an insertional translocation of chromosome 16p13.3 into the short arm of chromosome 22, karyotype 46,XY,.ish der(22),ins(22;16)(p13;p13.3p13.3) de novo. His clinical features overlap with the reported cases of 'duplication 16p' syndrome, namely a round face, hypertelorism, a long philtrum, micrognathia, a thin upper lip, a posterior cleft palate and low set, simple ears, clubbed feet, severe developmental delay, psychomotor retardation and seizures. This 4-year boy with trisomy 16p13.3 has the smallest duplication reported of this critical region, which could not be detected without array CGH. The maximal duplicated region is gene rich and contains about 80 genes and/or candidate genes. Assignment of the genes that contribute to the observed phenotype awaits the characterisation of other patients with small duplications in this region.     

Duplication 16q12.1-q22.1 characterized by array CGH in a girl with spina bifida

We report a 7-year-old girl with spina bifida carrying a complex chromosome abnormality resulting in duplication 16q12.1-q22.1. An abnormal karyotype was identified involving the long arm of chromosome 11 and fluorescent in situ hybridization (FISH) to metaphase chromosomes revealed an insertion of part of chromosome 16 on chromosome 11. A detailed mapping of the chromosome abnormality using whole genome array based comparative genomic hybridization (CGH) of the patient DNA revealed a duplication 16q12.1-q22.1 corresponding to gain of 19.8Mb of DNA without any detectable loss of genetic material on chromosome 11. The karyotype is defined as 46,XX,der(11)ins(11;16)(q13;q12.1q22.1). We present here the clinical findings and a fine mapping of the associated structural chromosome abnormalities. We suggest that a gene dosage imbalance of 16q12.1-q22.1 is associated with spina bifida in the patient.     

Clinical report: AN INTERSTITIAL deletion of 16p13.11 detected by array CGH in a patient with infantile spasms

Chromosome 16p13.11 has recently been reported as a region of recurrent microdeletion/duplication, which may contribute to a specific clinical phenotype of epilepsy, significant learning difficulties and distinct facial dysmorphism. The 16p13.11 microdeletion syndrome is associated with schizophrenia, developmental delay and idiopathic generalised epilepsy. Haploinsufficiency of genes in 16p13.11 has been suggested as contributing to the pathogenicity of this microdeletion syndrome. We report a three-year-old boy with the 16p13.11 microdeletion syndrome, identified on array CGH, and describe his clinical phenotype, thereby adding to the existing literature on this newly-described microdeletion syndrome. We discuss the function and potential relevance of the genes in this region with regards to the features described in this condition.     

Mental retardation in association with a balanced X-autosome translocation and random inactivation of the X chromosomes

A woman whose karyotype shows an apparently balanced reciprocal translocation, 46,X, t(Xq +; 10q —) is described. She is profoundly mentally retarded and shows minor physical abnormalities with normal sexual development. There is a random pattern of late replication of the normal X and the X involved in the translocation, whereas in most balanced X-autosome translocations there is preferential inactivation of the normal X.     

Deletion of the distal short arm of the X chromosome (Xp) in a patient with short stature,chondrodysplasia punctata,and X-linked ichthyosis due to steroid sulfatase deficiency

We observed a boy with short stature, chondrodysplasia punctata, ichthyosis, and a terminal deletion of Xp. Steroid sulfatase deficiency was demonstrated in the patient's fibroblasts. Molecular analysis showed a deletion of the entire steroid sulfatase gene. This case represents another example of a contiguous gene syndrome in which the co-deletion of adjacent genes on a chromosome is responsible for a complex phenotype.     

A 10.46 Mb 12p11.1-12.1 interstitial deletion coincident with a 0.19 Mb NRXN1 deletion detected by array CGH in a girl with scoliosis and autism

We present a 12-year-old girl with de novo karyotype 46,XX,del(12)(p11.1p12.1). Array CGH revealed in addition to a 10.466 Mb interstitial deletion on 12p11.1→12p12.1 a 0.191 Mb deletion on 2p16.3. The girl presented with mild facial dysmorphism consisting of microcephaly, hypertelorism, downslanting palpebral fissures, strabismus, broad nasal base, bulbous nose, short philtrum, micro/retrognathia, irregular tooth arrangement, phalangeal deformity in distal phalanges of hands, 5th finger camptodactyly, brachydactyly in feet, history of joint hypermobility, and scoliosis. She was considered to have mild to moderate mental retardation and ascertained for an autism spectrum disorder(ASD). Short arm of chromosome 12 interstitial deletions are rarely reported whereas point mutations and deletions of NRXN1, which is located on chromosome 2p16.3, are associated with ASDs. In this article we present and discuss the phenotypic consequences of a patient who was affected by deletions of two different chromosomal regions.     

Atypical 18p- syndrome associated with partial trisomy 16p in a chromosomally unbalanced child of consanguineous parents with an identical balanced translocation

A 2 month old male infant was found to have mild growth retardation, prominent forehead, low set ears, low nasal bridge, rounded facies, cleft palate, webbed neck, shawl scrotum, and absent right kidney. The propositus, a product of a consanguineous marriage, had extremely rare abnormal cytogenetic findings. His karyotype contained three derivative chromosomes that originated from a familial translocation, t(16;18)(p13.3;p11.2) carried by both parents. Based on parental studies, the infant's unbalanced karyotype was defined as: [46,XY,t(16;18)(p13.3;p11.2), der(18)t(16;18).ish t(16;18)(16ptel-,16qtel+,18ptel+,wcp16+,wcp18+;16ptel+,18ptel-,wcp16+,wcp18+), der(18)t(16;18)(16ptel+,18ptel-,wcp16+,wcp18+)]. We describe this child at 2 months of age with a follow up at 4 1/2 years, exhibiting a mixed clinical picture with features of both 18p- and partial trisomy 16p13.3.