Lissencephaly with der(17)t(17;20)(p13.3;p12.2)mat

The isolated lissencephaly sequence may be caused by point mutations of the LIS1 gene or by FISH-detectable microdeletions of the 17p13.3 region, which carries the LIS1 gene. These have various patterns of phenotypic presentations, including the Miller-Dieker syndrome (MDS). Approximately 20% of these deletions are associated with a derivative chromosome 17 inherited from a parent who has a balanced reciprocal translocation involving chromosome 17 and another chromosome. We report a case of lissencephaly associated with a maternally inherited unbalanced translocation involving chromosome arms 17p and 20p. This results in partial monosomy of 17p13.3-->pter and partial trisomy of 20p12.2-->pter. To our knowledge, this is the first report of a reciprocal translocation between 17p and 20p. Our patient has a combination of findings of the MDS and trisomy 20p, along with several unique anomalies not described in either of those two conditions. This report may contribute to the delineation of a phenotype resulting from partial monosomy 17p and partial trisomy of 20p.     

“Essentially pure” partial trisomy (6)(p23→pter) in two brothers due to maternal t(6;17)(p23;p13.3)

We report on two brothers with low birth weight, growth retardation, microcephaly, minor facial anomalies, mental retardation, and trisomy (6)(p23→pter) due to a maternal t(6;17)(p23;p13.3). As demonstrated by fluorescent in situ hybridisation (FISH) with the Miller-Dieker cosmid probe (D17S379) and with a subtelomeric probe (D17S34) the additional deletion on 17p13 is very small, and therefore, the phenotype of these two boys is most likely the result of essentially pure partial trisomy 6p. Comparison of the clinical findings with those of ten cases from the literature of dup(6p) with a breakpoint in or more distal to 6p23 allows delineation of a specific phenotype of dup(6)(p23→pter) characterized by low birth weight, growth retardation, microcephaly, and blepharophimosis, blepharoptosis, microstomia, and abnormal ears. Am. J. Med. Genet. 85:389–394, 1999. © 1999 Wiley-Liss, Inc.     

Two sibs with different phenotypes due to adjacent-1 segregation of a subtle translocation t(4;5)(p16.3;p15.3) mat

High-resolution chromosome banding and in situ hybridization with combined cosmid and alphoid sequence probes were used to delineate a very small reciprocal translocation in a mother and her two children. The first child has a 46,XX,der(4)t(4;5)(p16.3;p15.3)mat and thus has a deletion of 4p16.3→pter and a duplication of 5p15.3→pter (most likely 5p15.31→pter). Clinical findings include marked growth retardation, developmental delay, seizure disorder, microcephaly, unruly hair, broad nasal tip, downturned mouth, narrow palate, 11 pairs of ribs,mild right club foot, and a deep sacral dimple. Thus, this child has only a few non-specific manifestations of Wolf-Hirschhorn syndrome. The second child has a 46,XY,der(5)t(4;5)(p16.3;p15.3)mat; thus a deletion of 5p15.3→pter and a duplication of 4p16.3→pter. He has failure to thrive, developmenatal delay, microcephaly, sparse hair, horizontal nystagmus, short upturned nose with flared nostrils, thin lips with overhanging upper lip, long fingers and toes, and hypertonicity. Findings in the second patient are not suggestive of cri du chat syndrome (del 5p). The mother is phenotypically normal. This translocation will be useful in mapping genes and markers on the 4p and 5p chromosomal regions. © 1993 Wiley-Liss, Inc.     

"Essentially pure" partial trisomy (6)(p23-->pter) in two brothers due to maternal t(6;17)(p23;p13.3).

We report on two brothers with low birth weight, growth retardation, microcephaly, minor facial anomalies, mental retardation, and trisomy (6)(p23-->pter) due to a maternal t(6;17)(p23;p13.3). As demonstrated by fluorescent in situ hybridisation (FISH) with the Miller-Dieker cosmid probe (D17S379) and with a subtelomeric probe (D17S34) the additional deletion on 17p13 is very small, and therefore, the phenotype of these two boys is most likely the result of essentially pure partial trisomy 6p. Comparison of the clinical findings with those of ten cases from the literature of dup(6p) with a breakpoint in or more distal to 6p23 allows delineation of a specific phenotype of dup(6)(p23-->pter) characterized by low birth weight, growth retardation, microcephaly, and blepharophimosis, blepharoptosis, microstomia, and abnormal ears.     

Miller-Dieker syndrome due to maternal cryptic translocation t(10;17)(q26.3;p13.3)

We report on a 3-month-old girl with Miller-Dieker syndrome resulting from a maternal full-cryptic translocation t(10;17)(q26.3;p13.3) detectable only by using fluorescence in situ hybridization (FISH). Parental studies using FISH are crucial for genetic counselling in cases of Miller-Dieker syndrome with submicroscopic deletion at 17p13.3. In a family with a parental cryptic translocation and high recurrence risk, prenatal diagnosis using FISH is feasible. © 1995 Wiley-Liss, Inc.     

Clinical and molecular genetic findings in five patients with Miller-Dieker syndrome

Five patients with type 1 lissencephaly, typical features of Miller-Dieker syndrome and apparently normal karyotypes were investigated for microdeletions in chromosome 17p13.3. Analysis of loci D17S5 and D17S379 by polymerase chain reaction and fluorescence in situ hybridization revealed a deletion in three cases. No deletion was observed in the remaining two cases. Given the almost identical clinical picture of the five patients, the great variation in the molecular findings argues against Miller-Dieker syndrome being a contiguous gene syndrome.     

Case of partial trisomy 9p and partial trisomy 14q resulting from a maternal translocation: Overlapping manifestations of characteristic phenotypes

We report on a female infant with partial trisomy 9p (pter→p13) and partial trisomy 14q (pter→q22) resulting from a 3:1 segregation of a maternal reciprocal translocation (9;14)(p13;q22). Both trisomy 9p and partial trisomy 14q have been described as recognized phenotypes with characteristic patterns of anomalies. This patient appears to be the first reported with a partial duplication of both 9p and 14q resulting in an overlapping phenotype including minor facial anomalies, cleft palate, and hand-foot anomalies. However, the facial findings were more pronounced than commonly observed in cases with only one or the other duplicated chromosome regions, resulting in a distinctive appearance. Am. J. Med. Genet. 84:132–136, 1999. © 1999 Wiley-Liss, Inc.     

A new 17p13.3 microduplication including the PAFAH1B1 and YWHAE genes resulting from an unbalanced X;17 translocation

Submicroscopic duplications of the genomic interval deleted in Miller-Dieker syndrome (MDS) were recently identified by array-based comparative genomic hybridization (a-CGH) studies, describing new genomic disorders in the MDS locus. These rearrangements of varying size, from 59-88 kb to 4 Mb, were non-recurrent, and appear to result from diverse molecular mechanisms. Only five patients had overlapping 17p13.3 duplications including the entire MDS critical region. We describe here a 13-year-old girl with a novel microduplication of the MDS critical region, involving the PAFAH1B1 and YWHAE genes. She presented with moderate psychomotor retardation, speech delay, behavioral problems, and bilateral cleft lip and palate, a previously unreported manifestation. Initially diagnosed as having an apparently simple terminal Xq26 deletion on standard cytogenetic analysis, she was found to have an associated terminal 4.2 Mb 17p13.3 submicroscopic duplication, identified by subtelomere FISH analysis, further characterized by high-resolution array CGH, resulting from an unbalanced X;17 translocation. Phenotypic comparison with the 5 other patients previously described, revealed common phenotypic features, such as hypotonia, mild to moderate developmental delay/mental retardation, speech abnormalities, behavioral problems, recurrent infections, relatively increase of body weight, discrete facial dysmorphism including downslanting palpebral fissures, broad midface, pointed chin, contributing to further delineate this new 17p13.3 microduplication syndrome.     

Unbalanced translocation (15;17)(q13;p13.3) with apparent Prader-Willi syndrome but without Miller-Dieker syndrome

We studied after death a 3-month-old girl whose karyotype was 45,XX, ? 15, ? 17, + der(17),t(15;17)(q13;p13.3) and thus combines abnormalities of chromosome 15 associated with the Prader-Willi syndrome and of chromosome 17 associated with the Miller-Dieker syndrome. This infant had several manifestations of the Prader-Willi syndrome in infancy but none of the Miller-Dieker syndrome. We propose that essentially no loss of 17p material has occurred and confirm previous reports that the critical region for the production of the Miller-Dieker phenotype is located subterminally in the 17p13.3 region.     

17p11.2p12 triplication and del(17)q11.2q12 in a severely affected child with dup(17)p11.2p12 syndrome

Multiple congenital anomalies/mental retardation syndromes due to genomic rearrangements involving chromosome 17p11.2 include deletion resulting in Smith-Magenis syndrome and a reciprocal duplication of the same region resulting in the 17p11.2 duplication syndrome. We present the clinical and molecular analysis of an 8-year-old male with a dup(17p11.2p12) who was evaluated for unusual severity of the phenotype. Fluorescent in situ hybridization (FISH) analysis not only confirmed the 17p duplication but also identified an approximately 25% mosaicism for tetrasomy 17p11.2p12. Whole-genome array comparative genomic hybridization (aCGH) was performed to identify other genomic rearrangements possibly contributing to the severe phenotype and the unusual features in the patient. The 17p duplication was determined by FISH and aCGH to encompass approximately 7.5 Mb, from COX10 to KCNJ12. An approximately 830 Kb deletion of 17q11.2q12, including exon 1 of an amiloride-sensitive cation channel neuronal gene, ACCN1, was also identified by aCGH; breakpoints of the deletion were confirmed by FISH. Sequencing the non-deleted allele of ACCN1 did not show any mutations. Western analysis of human tissue-specific proteins revealed that ACCN1 is expressed not only in the brain as previously reported but also in all tissues examined, including heart, liver, kidneys, and spleen. The large-sized 17p11.2p12 duplication, partial triplication of the same region, and the 17q11.2q12 deletion create a complex chromosome 17 rearrangement that has not been previously identified. This is the first case of triplication reported for this chromosome. Our study emphasizes the utility of whole-genome analysis for known cases with deletion/duplication syndromes with unusual or severe phenotypes.     

A large interstitial deletion of 17p13.1p11.2 involving the Smith-Magenis chromosome region in a girl with multiple congenital anomalies

A 6-month-old girl had multiple congenital anomalies, including dysmorphic face; tetralogy of Fallot, pulmonary atresia and patent ductus arteriosus; congenital cystic adenomatoid malformation of the right upper lung, and hemilateral kidney defect. Chromosome analysis as well as fluorescence in situ hybridization (FISH) and polymorphic marker analyses in the girl and her parents revealed a de novo large interstitial deletion of 17p13.1-p11.2 of the paternally derived chromosome 17. The deletion involved the Smith-Magenis chromosome region (SMCR). Lack of involvement of the Miller-Dieker syndrome region at 17p13.3 was confirmed by both FISH analysis and radiological examinations that showed no migrational abnormality. The girl died at age 7 months. This is the first report of a patient with a large interstitial deletion of 17p.     

Complementary duplication and deletion of 17 (pcen→p11.2): A family with a supernumerary chromosome comprised of an interstitially deleted segment

A sister and brother were investigated because both were developmentally delayed although they had somewhat different physical anomalies. The girl was found to have an interstitial deletion of chromosome 17. Her karyotype was 46,XX,del(17) (pter→p11.2:: cen→qter). Her brother had normal chromosomes in peripheral lymphocytes. Cytogenetic investigation of the mother showed the presence of the same deletion as in her daughter and a small supernumerary chromosome. The supernumerary chromosome appeared to contain the material deleted from the short arm of 17 since the mother's phenotype was normal. Study of skin fibroblasts in her son showed that he was mosaic for a normal cell line and one that contained the extra small chromosome; thus, he had mosaic partial trisomy 17(cen→p11.2). The origin of the centromere and telomere(s) of the small supernumerary chromosome in this family presents an interesting problem. © wiley-Liss, Inc.     

Segregation of three reciprocal translocations in the same family: t(3;4), t(5;10), and t(15;21)

A male infant with static antenatal encephalopathy and epilepsy was found to have a duplication of 5p12→5pter and deficiency of 10p13→10pter. Each of his parents was a carrier of a balanced reciprocal translocation. A third translocation was found in the maternal grandfather. The pedigree of each translocation and the segregation of parental reciprocal translocations are discussed.     

12p13 rearrangements: 6 Mb deletion responsible for ID/MCA and reciprocal duplication without clinical responsibility

Congenital balanced reciprocal translocations are one of the most frequent structural chromosomal aberrations in the population. We report a familial translocation t(12;22)(p13.3;pter) responsible for intellectual disabilities and congenital anomalies characterized by FISH and array CGH. Two patients carried a der(12)t(12;22)(p13.3;pter), resulting in a 6 Mb 12pter deletion. Patients presented with intellectual disabilities, pre- and post-natal growth retardation, ponderal development delay, global hypotonia, feeding problems and dysmorphic features. Two relatives presented with the reciprocal 12pter duplication, which had no clinical manifestations associated. For this translocation, we propose a mechanism based on a non-allelic recombination model, in which recombination of direct oriented segmental duplications between non-homologous chromatids leads to the reciprocal translocation. The characterization of this translocation has been critical for the family. Translocation carriers have a risk of 40% of having offspring carrying unbalanced products. 12p13.3 deletion carriers present with a recognizable syndrome and on the contrary, 12p13.3 duplication carriers present without clinical manifestations. Other published cases of 12p13.3 duplication show that this syndrome has a variable phenotype. It is advisable to delineate the duplication size and to discard other genetic aberrations, in order to give an accurate genetic counseling in patients carrying 12pter duplications.     

Interstitial deletion 8p21.3 → p23.1 in a 6-year-old girl

We present a 6-year-old mentally retarded girl. Chromosome analysis showed an interstitial deletion of chromosome 8; 46,XX,del(8) (pter → p23.1::p21.3 → qter). The proposita had normal activities of glutathione synthetase reductase (GSR) and factor VII. Parental chromosomes were normal.     

A microduplication on chromosome 17p13.1p13.3 including the PAFAH1B1 (LIS1) gene

Recently, three children with a microduplication in 17p13 including the PAFAH1B1 gene that encodes LIS1 were reported. LIS1 overexpression has earlier been shown to affect brain development by causing migrational defects and reductions in brain volume [Bi et al., 2009]. Here, we report an additional patient with a microduplication on chromosome 17p13.1p13.3 including the PAFAH1B1 gene, that was inserted into the long arm of chromosome 4. The patient had psychomotor and growth retardation, dysmorphic features, small ventricular septal defect (VSD), and immunoglobulin abnormality. Only subtle abnormalities in brain MRI scan were seen. Interestingly, the facial features of our patient closely resemble those previously reported in 17p trisomy patients.     

Array-CGH study of partial trisomy 9p without mental retardation

Partial trisomy 9p is one of the most common detected autosomal structural anomalies, so the phenotype-genotype correlation of this rearrangement has been well described. Despite variation in size of the 9p duplications, trisomy 9p syndrome is characterized by typical dysmorphic features and a variable but constant psychomotor and mental retardation. Previously reported phenotype genotype correlation studies proposed that the critical region for phenotype is located in 9p22. We report here on a new patient with partial trisomy 9p13.3→9pter in an 8-year-old boy with typical trisomy 9p dysmorphic features but a normal mental development. Cytogenetics investigations showed that our patient karyotype was 47,XY,+ der(22)t(9;22)(p13.q11) inherited by a 3:1 disjunction of a maternal reciprocal translocation t(9;22)(p13.q11). FISH and array CGH analysis were used to better characterize duplicated chromosomal regions and showed a large duplication of chromosome 9p13.3→9pter associated to microduplication in 22q11.1. The size of the duplications in chromosomes 9p and 22q were estimated about 33.9 and 2.67 Mb, respectively. The comparison between this case and those reported in the literature allows us to support that all syndromes show variability and that not all partial trisomies 9p are associated with intellectual disability.     

Further expansion and confirmation of phenotype in rare loss of YWHAE gene distinct from Miller–Dieker syndrome

Deletion of 17p13.3 has varying degrees of severity on brain development based on precise location and size of the deletion. The most severe phenotype is Miller–Dieker syndrome (MDS) which is characterized by lissencephaly, dysmorphic facial features, growth failure, developmental disability, and often early death. Haploinsufficiency of PAFAH1B1 is responsible for the characteristic lissencephaly in MDS. The precise role of YWHAE haploinsufficiency in MDS is unclear. Case reports are beginning to elucidate the phenotypes of individuals with 17p13.3 deletions that have deletion of YWHAE but do not include deletion of PAFAH1B1. Through our clinical genetics practice, we identified four individuals with 17p13.3 deletion that include YWHAE but not PAFAH1B1. These patients have a similar phenotype of dysmorphic facial features, developmental delay, and leukoencephalopathy. In a review of the literature, we identified 19 patients with 17p13.3 microdeletion sparing PAFAH1B1 but deleting YWHAE. Haploinsufficiency of YWHAE is associated with brain abnormalities including cystic changes. These individuals have high frequency of epilepsy, intellectual disability, and dysmorphic facial features including prominent forehead, epicanthal folds, and broad nasal root. We conclude that deletion of 17p13.3 excluding PAFAH1B1 but including YWHAE is associated with a consistent phenotype and should be considered a distinct condition from MDS.     

A case of Miller-Dieker syndrome associated with satellite on chromosome 17p

In this report, we describe a one-year-old girl of the Miller-Dieker syndrome(MDS) with lissencephaly, seizures, microcephaly and mental disorders. Cytogenetic studies of this patient confirmed the presence of a 46,XX, 17ps+ chromosome karyotype, but it could not find the microdeletion of 17p13.3. Fluorescence in situ hybridization(FISH) studies confirmed a terminal deletion in the patient using the LIS1 gene probe which mapped to 17p13.3. Further it was also found the satellite on 17p13(17ps) in the patient who was rare associated with MDS. These findings suggest that FISH analysis may be useful method to detect microdeletion of LIS1 gene as 17-specific probe in the investigation of MDS patients.     

Omphalocele in Miller-Dieker syndrome: Expanding the phenotype

We report on a patient prenatally diagnosed with omphalocele, mild cerebral ventriculomegaly, nuchal fold thickening, and cystic changes in the umbilical cord who was found postnatally to have lissencephaly type I. Prenatal chromosome analysis showed a normal male karyotype; however, postnatal high resolution banding and FISH analysis, using a probe for locus D17S379 in chromosome region 17p13.3, demonstrated a deletion at 17p13.3 consistent with Miller-Dieker syndrome (MDS). A review documented four more cases with MDS/isolated lissencephaly/17p-, with omphalocele. Because MDS is a contiguous gene disorder, we speculate that a gene or genes in this region have a major role in the closure of the lateral folds or the return of the midgut from the body stalk to the abdomen at 5–11 weeks of gestation. Prenatal diagnosis of omphalocele with mild ventriculomegaly should prompt FISH analysis for a deletion in 17p13.3. Am. J. Med. Genet. 69:293–298, 1997. © 1997 Wiley-Liss, Inc.