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Partial monosomy of chromosome 1p36.3: characterization of the critical region and delineation of a syndrome.

We describe 5 patients ranging in age from 3 to 47 years, with karyotypic abnormalities resulting in monosomy for portion of 1p36.3, microcephaly, mental retardation, prominent forehead, deep-set eyes, depressed nasal bridge, flat midface, relative prognathism, and abnormal ears. Four patients have small hands and feet. All exhibited self-abusive behavior. Additional findings in some of the patients include brain anomalies, optic atrophy, hearing loss and skeletal deformities. The breakpoints within chromosome 1 were designated at 1p36.33 (1 case). Thus, the smallest region of deletion overlap is 1p36.33-->1pter. Detection of the abnormal 1 relied on high resolution G-band analysis. Fluorescence in situ hybridization (FISH) utilizing a DNA probe (Oncor D1Z2) containing the repetitive sequences in distal 1p36, confirmed a deletion of one 1 homologue in all 5 cases. The abnormal 1 resulted from a de novo deletion in only one patient. The remaining patients were either confirmed (3 cases) or suspected (1 case) to have unbalanced translocations. Despite the additional genetic imbalance present in these four cases, monosomy of 1p36.33 appears to be responsible for a specific clinical phenotype. Characterization of this phenotype should assist in the clinical diagnosis of this chromosome abnormality.

Abnormalities, Multiple↗

Distal deletion, del(2)(q33.3q33.3), in a patient with severe growth deficiency and minor anomalies.

We report on an 18-month-old boy with a 2q33.3 deletion. The clinical findings observed in the propositus included minor anomalies of face and distal limbs, intrauterine and postnatal growth retardation, microcephaly and, so far, moderate developmental delay. Conventional GTG banded chromosome analysis indicated a small deletion in distal 2q. Subsequent analysis by fluorescent in situ hybridization (FISH) using different probes allowed us to narrow down the deletion to most or all of segment 2q33.3. This case shows the importance of the application of different YAC probes for a precise determination of breakpoints in small interstitial deletions.

Abnormalities, Multiple↗

Provisionally unique autosomal recessive syndrome due to significant consanguinity.

We report a patient with a syndrome of MR/MCA who was the product of a highly consanguineous family. The patient was the result of a union between a man and his daughter. The daughter was in turn the product of a mating between this same man and his mother. Major findings include: severe psychomotor and mental retardation, microcephaly with cerebral dysgenesis and cerebellar hypoplasia, early hypotonia and late hypertonia, short stature, early swallowing incoordination with aspiration pneumonias, distinctive face with striking hypertelorism, hypospadias, cryptorchidism, overlapping fingers, and rocker-bottom feet. Chromosome and metabolic studies were normal. The severity and uniqueness of his phenotype suggests a new, probably private, autosomal recessive disorder due to homozygosity for one or more loci.

Abnormalities, Multiple↗

Cancer-prone syndrome of mosaic variegated aneuploidy and total premature chromatid separation: report of five infants.

Five infants (two girls and three boys) from four families all had severe pre- and postnatal growth retardation, profound developmental delay, microcephaly, hypoplasia of the brain with Dandy-Walker complex or other posterior fossa malformations, and developed uncontrollable clonic seizures. Four infants developed Wilms tumors, and one showed cystic lesions in bilateral kidneys. All five infants showed variegated mosaic aneuploidy in cultured lymphocytes. In two infants whose chromosomes were prepared by us, 48.5%-83.2% lymphocytes showed total premature chromatid separation (PCS). Their parents had 3.5%-41.7% of their lymphocytes in total PCS. The remaining three infants and their parents, whose chromosomes were prepared at outside laboratories, tended to show lower frequencies of total PCS. Another five infants reported with the disorder were reviewed together with the five infants we described. Together, their clinical and cytogenetic manifestations were similar enough to suggest a syndrome. Seven of the 10 infants developed proven or probable Wilms tumors. The age at diagnosis of the tumors was younger than usual at 2-16 months. The tumors were bilateral in four infants and unilateral in three infants, and cystic changes were present in six infants. Two infants developed botryoid rhabdomyosarcoma. The carriers of the syndrome are thus liable to tumorigenesis. The possible role of mitotic checkpoint defects, proven in two infants with the syndrome (Matsuura et al. [2000: Am J Hum Genet 69:483-486]), was discussed in connection with tumor development and progression.

Abnormalities, Multiple↗

Newborn with malformations and a combined duplication of 9pter-q22 and 16q22-qter resulting from unbalanced segregation of a complex maternal translocation.

We report a patient with duplication of 9pter-q22 combined with duplication of 16q22-qter. The chromosome anomaly was the result of a 3:1 segregation of a maternal translocation (46,XX,t[9;16;21]). This newborn had intrauterine growth retardation and microcephaly, the characteristic recognizable pattern of trisomy 9p, cerebellar hypoplasia, a porencephalic cyst in the parieto-occipital region, and rocker-bottom feet. We compare the clinical features with another previously described case of duplication of an identical 9p segment combined with distal 16q duplication of a similar, but not identical segment, as well as with cases with duplication of either one of the two segments.

Abnormalities, Multiple↗

Ring chromosome 12 with variable phenotypic features: clinical report and review of the literature.

A ring chromosome 12 (p13; q24.33) was observed in all cells analyzed from peripheral blood lymphocytes of a 15-year-old female referred for academic difficulties and growth delay. In addition to clinical manifestations generally observed with ring chromosome 12 such as growth retardation, mental deficiency, microcephaly, the patient had bilateral pseudocamptodactyly of little fingers, mild hirsutism, exaggerated lumbar lordosis, and ostium secundum atrial septal defect (ASD). The clinical features of reported cases are analyzed. The only consistent features were growth retardation and mental deficiency. Breakpoint in all the cases has been at the telomeric region with minimal deletion of chromosomal material. An account of complex changes at mitosis and meiosis in ring chromosome has been given. Examination of 200 metaphases demonstrated 2% cell line was showing 45,XX, -12. Serum lactate dehydrogenase (LDH) level was normal ruling out overlapping monosomy 12 syndrome.

Abnormalities, Multiple↗

van den Ende-Gupta syndrome of blepharophimosis, arachnodactyly, and congenital contractures: clinical delineation and recurrence in brothers.

We describe two Hispanic brothers born to unrelated parents with van den Ende-Gupta syndrome (VDEGS), a distinctive combination of characteristic dysmorphic features, skeletal abnormalities, and cerebellar hyperplasia. This syndrome was previously delineated by van den Ende et al. [1992: Am J Med Genet 42:467-469] and Gupta et al. [1995: J Med Genet 32:809-812], with additional reports by Phadke et al. [1998: Am J Med Genet 77:16-18] and Bistritzer et al. [1993: Clin Genet 44:15-19]. This is the fifth report of VDEGS, which is characterized by blepharophimosis, narrow nose with hypoplastic alae nasi, hypoplastic maxilla, everted lower lip, slender and elongated hands and feet, arachnodactyly, self-limiting joint contractures, and distinctive skeletal findings. This report of affected siblings, and a previous report of double second cousins born to consanguineous parents [Bistritzer et al. [1993: Clin Genet 44:15-19]], suggests autosomal recessive inheritance. This brings to eight, the total number of reported cases, derived from six families, three of which are consanguineous. It is important to distinguish VDEGS from Marden-Walker syndrome (MWS) since both syndromes include blepharophimosis, arachnodactyly, and congenital contractures. Both syndromes are inherited in an autosomal recessive fashion, but VDEGS lacks severe mental retardation, serious brain malformations, microcephaly, failure to thrive, and severe joint limitation, which are consistently present in MWS. Of particular importance, MWS may be associated with cerebellar malformations such as Dandy-Walker malformation, while the brothers reported herein with VDEGS both demonstrated distinctive cerebellar enlargement, a new finding for this disorder. While, congenital contractures with arachnodactyly are features commonly seen in several other delineated syndromes, such as congenital contractural arachnodactyly (CCA) syndrome, characteristic facial features (blepharophimosis, narrow nose with ocular hypertelorism, prominent ears, and everted lower lip), distinguish VDEGS from other syndromes associated with CCA, including CCA.

Blepharophimosis↗

Deletion 12q: a second patient with 12q24.31q24.32 deletion.

We report on a 20-month-old patient with facial dysmorphisms, microcephaly, cardiac septal defects, global developmental delay, and failure to thrive. Karyotypic evaluation revealed an interstitial deletion of the long arm of one chromosome 12, del(12)(q24.31q24.32). Only one other patient with a similar deletion has been reported previously. By comparing the two patients, we can begin to identify a characteristic phenotypic pattern.

Abnormalities, Multiple↗

Child with De Novo t(1;6)(p22.1;p22.1) translocation and features of ectodermal dysplasia with hypodontia and developmental delay.

We report on a 6.5-year-old girl with a balanced translocation between the short arms of chromosomes 1 and 6. She was referred for genetics evaluation because of developmental speech delay and congenital absence of several deciduous and permanent teeth. She was very sensitive to noise (hyperacusis), had poor hair and nail growth, decreased sweating, and turned very red with high fever. She had microcephaly (head circumference at the second centile; weight and height were at 25th centile), short palpebral fissures, epicanthal folds, sparse eyelashes, large ears, partial anodontia, short finger and toenails, and dry skin. She had mild developmental delay. Family history was significant for learning problems in two paternal uncles, one paternal aunt, and several paternal cousins. Thyroid studies, calcium, phosphorus, and alkaline phosphatase levels were normal. Her karyotype was 46,XX,t(1;6)(p22.1;p22.2), and parental karyotypes were normal. This apparently balanced translocation may have resulted in either a submicroscopic loss or disruption of a gene or genes involved in ectodermal dysplasia. There are no reported cases of ectodermal dysplasia associated with this chromosome rearrangement.

Anodontia↗

Johnson-McMillin syndrome, a neuroectodermal syndrome with conductive hearing loss and microtia: report of a new case.

In 1983, Johnson et al. described 16 related individuals with alopecia, anosmia or hyposmia, conductive hearing loss, microtia and/or atresia of the external auditory canal, and hypogonadotrophic hypogonadism inherited in an autosomal dominant pattern. Other less constant manifestations included facial asymmetry, mental retardation, congenital heart defect, cleft palate, and choanal stenosis. An isolated case was reported later (Johnston et al. [1987: Am J Med Genet 26: 925-927]) and thereafter an affected mother and son (Hennekam and Holtus [1993: Am J Med Genet 47: 714-716]). We describe an additional unrelated female patient with features resembling those of the previously reported cases. She presented with intrauterine growth deficiency, microcephaly, alopecia, bilateral microtia with canal atresia, conductive hearing loss, partial left facial palsy, posterior cleft palate, left choanal stenosis, tetralogy of Fallot, developmental delay, and right thumb polydactyly. Because the phenotypic abnormalities in this syndrome affect the brain, facial structures, ectoderm and its derivatives, outflow tract of the heart, and Rathke's pouch derivatives, this has suggested to previous authors etiologic involvement of the ectoderm and neuroectoderm of the first and second branchial arches, Rathke's pouch, and the diencephalon. Microtia with conductive hearing loss differentiates the condition from other ectodermal dysplasias. In the initial report, females appeared somewhat less affected than males, and there was male-to-male transmission. The mother of our patient manifests subtle features, which suggest she may be a mildly affected female. Additionally, there is a family history of early-onset alopecia in the maternal grandfather's relatives.

Abnormalities, Multiple↗

Angelman syndrome associated with oculocutaneous albinism due to an intragenic deletion of the P gene.

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by mental retardation, speech impairment, ataxia, and happy disposition with frequent smiling. AS results from the loss of expression of a maternal imprinted gene, UBE3A, mapped within 15q11-q13 region, due to different mechanisms: maternal deletion, paternal UPD, imprinting center mutation, and UBE3A mutation. Deletion AS patients may exhibit hypopigmentation of skin, eye, and hair correlating with deletion of P gene localized in the distal part of Prader-Willi (PWS)/AS region. Our patient presented developmental delay, severe mental retardation, absence of speech, outbursts of laughter, microcephaly, ataxia, hyperactivity, seizures, white skin, no retinal pigmentation, and gold yellow hair. His parents were of African ancestry. The SNURF-SNRPN methylation analysis confirmed AS diagnosis and microsatellite studies disclosed deletion with breakpoints in BP2 and BP3. All of the 25 exons and flanking introns of the P gene of the patient, his father, and mother were investigated. The patient is hemizygous for the deleted exon 7 of the P gene derived from his father who is a carrier of the deleted allele. Our patient manifests OCA2 associated with AS due to the loss of the maternal chromosome 15 with the normal P allele, and the paternal deletion in the P gene. As various degrees of hypopigmentation are associated with PWS and AS patients, the study of the P gene in a hemizygous state could contribute to the understanding of its effect on human pigmentation during development and to disclose the presence of modifier pigmentation gene(s) in the PWS/AS region.

Albinism, Oculocutaneous↗

New syndrome of simplified gyral pattern, micromelia, dysmorphic features and early death.

We report two sisters with a new syndrome of simplified gyral pattern, normal head circumference at birth but with subsequent development of microcephaly, intractable seizures, and early death. Dysmorphic features included coarse face, hypertrichosis, short nose, paranasal widening, long philtrum, short neck, upper limb micromelia, single transverse palmar lines, and clasp thumbs. The proband had repeated convulsions from shortly after birth and she required continuous artificial ventilation. Neurological examination showed absent sucking, rooting, Moro and grasping reflexes. MRI revealed a diffuse simplified gyral pattern with apparent agyria over the frontal lobes. Biochemical screening gave normal results. Her older sister had bilateral renal pelvic dilatation on prenatal ultrasound. She also developed severe convulsions on the first day of life, and she had to be artificially ventilated for 38 days. She had severe developmental retardation and neurological examination showed absence of spontaneous movements and Moro reflex, weak sucking reflex, and hypertonicity. CT scan of the brain showed a simplified gyral pattern. At 3 months, she developed hypocalcemia and hyperphosphatemia with normal levels of vitamin D and alkaline phosphatase, and parathyroid hormone level was low. Other biochemical tests gave normal results. She died at 5 months due to a massive aspiration event. Based on the unique clinical and radiological features found in our patients, we propose that this is a new syndrome.

Brain Diseases↗

Myoclonus in a patient with a deletion of the epsilon-sarcoglycan locus on chromosome 7q21.

Autosomal dominant myoclonus-dystonia syndrome (MDS) is characterized by myoclonic and/or dystonic movements with onset as early as infancy. In most families, MDS is caused by mutations in the gene SGCE, which encodes epsilon -sarcoglycan and is located on chromosome 7q21. Data from several sources, including multi-generation pedigrees revealing parent-of-origin effects on MDS penetrance, suggest that SGCE is maternally imprinted. We present a 32-month-old patient with an interstitial deletion affecting chromosome 7q21, and a phenotype including myoclonus, microcephaly, short stature, dysmorphic face and language delay. We used fluorescence in situ hybridization (FISH) to estimate the size of our patient's deletion (9.0-15 Mbp) and to confirm absence of SGCE on the affected chromosome. Polymerase chain reaction (PCR) analysis of polymorphic markers in the region revealed that the paternally inherited chromosome contained the deletion, consistent with a model of maternal SGCE imprinting. Our patient is the first case of MDS caused by complete deletion of SGCE, and represents a new contiguous gene disorder. The case underscores the need to consider chromosomal deletions in patients whose phenotypes are more complex than the classic presentation of a known disease.

Child, Preschool↗

Partial hexasomy of chromosome 15.

Marker chromosomes originating from chromosome 15, often referred to as inv dup(15), is the most common marker chromosome found in humans. The large marker 15 that contains the Prader-Willi syndrome (PWS)/Angelman syndrome (AS) chromosome region is usually associated with an abnormal phenotype of moderate to severe mental retardation, seizures, poor motor coordination, behavioral problems, and mild dysmorphic features. We report here an infant boy with two copies of the large inv dup(15). A 10-day-old infant was found to have infantile spasms, microcephaly, hypotonia, and lethargy. Lymphocyte chromosome analysis revealed a 48,XY, +2mar karyotype. Fluorescence in situ hybridization with probes rRNA, D15Z4, D15S11, and GABRB3 demonstrated that both markers were chromosome 15 in origin and contained the Prader-Willi/Angelman syndrome chromosome region. Therefore, this patient is hexasomic for the PWS/AS region. The phenotype of this patient does not appear to be significantly more severe than patients with one copy of the large inv dup(15) at birth, however, follow-up evaluation of the patient at 21 months of age shows that this patient has frequent and severe seizure activity, severe bilateral hearing loss, and cortical blindness.

Adult↗

657del5 mutation in the gene for Nijmegen breakage syndrome (NBS1) in a cohort of Russian children with lymphoid tissue malignancies and controls.

Nijmegen breakage syndrome (NBS, OMIM 251260) is a rare hereditary disease, characterized by immune deficiency, microcephaly, and an extremely high incidence of lymphoid tissue malignancies. The gene mutated in NBS, NBS1, was recently cloned from its location on chromosome 8q21. The encoded protein, nibrin (p95), together with hMre11 and hRad50, is involved in the double-strand DNA break repair system. We screened two Russian cohorts for the 657del5 NBS1 mutation and found no carriers in 548 controls and two carriers in 68 patients with lymphoid malignancies: one with acute lymphoblastic leukemia (ALL) and one with non-Hodgkin lymphoma (NHL). Several relatives of the second patient, who were carriers of the same mutation, had cancer (ALL, breast cancer, GI cancers). These preliminary data suggest that NBS1 mutation carriers can be predisposed to malignant disorders.

Base Sequence↗

Juberg-Hayward syndrome: report of a new patient with severe phenotype and novel clinical features.

We report a patient with severe mental retardation (MR), microcephaly, Dandy-Walker malformation, bilateral lip/palate clefts, hypertrophied sublingual frenulum, lobular tongue, absent thumbs, and other skeletal abnormalities, including Y-shaped metacarpals and urogenital abnormalities. High-resolution karyotype and subtelomeric fluorescence in situ hybridization were normal. We propose that his clinical picture is most consistent with Juberg-Hayward or orocraniodigital syndrome. Several clinical features present in our patient (unilateral distal displacement of elbow position, second-site radioulnar synostosis, bilateral Y-shaped metacarpal, lobular tongue, hypertrophic frenuli, Dandy-Walker malformation) have not previously been reported in this condition, thus expanding the phenotypic spectrum of this rare condition. The presence of these novel findings suggests possible overlap with other syndromes, such as orofaciodigital and Malpuech syndromes.

Adolescent↗

Genitopatellar syndrome: expanding the phenotype.

Genitopatellar syndrome is a recently described disorder with characteristic facies, genital anomalies, absent patella, flexion contractures, microcephaly, renal anomalies, and mental retardation. The presence of affected siblings in two of the original families suggests autosomal recessive inheritance. We report a new patient that exhibits all of these cardinal features and is also the second case to have additional, more severe findings including a congenital heart defect, anal anomalies, and features of an ectodermal dysplasia, thus expanding the phenotype to include these manifestations.

Facies↗

Thyroid dysfunction in a patient with aglossia.

We report a Thai girl who had aglossia, micrognathia, microsomia, collapse of mandibular arch, persistence of buccopharyngeal membrane, microcephaly, and mild developmental delay. Thyroid function tests indicated that she had subclinical hypothyroidism. Thyroid scan revealed normal uptake of the whole thyroid gland. Tongue morphogenesis is integrally linked to the normal development of thyroid gland, and abnormal tongue morphogenesis could potentially result in a functional thyroid disorder. We propose that micrognathia, microsomia, congenital absence of mandibular incisors, and collapse of the mandibular arch are the result of abnormal tongue development.

Abnormalities, Multiple↗