Interstitial deletion (6) (q11----q15) in an infant with congenital abnormalities

Proximal Deletion of 6q Overlapping with Toriello-Carey Facial Phenotype: Prenatal Findings, Clinical Course, Differential Diagnosis, and Review

Proximal deletion of 6q is a relatively rare chromosomal abnormality. Reported patients have deletions of different sizes but share partial overlap and present with similar clinical features, and some of them were described prior to the introduction of chromosome microarrays. We describe a male patient with prenatal sonographic findings of nuchal edema, intrauterine growth restriction, renal pelvis dilatation, and oligohydramnios. At birth, facial dysmorphism, retro/micrognathia, a short and wide neck as well as cardiovascular and renal anomalies were noted. His clinical evolution has been marked by failure to thrive, severe developmental delay, and cognitive impairment. The diagnosis of Toriello-Carey syndrome (TCS) was based on his "gestalt." aCGH identified a de novo proximal deletion of 17 Mb in 6q (6q12q14.3). Deletion 6q13q14 seems to be responsible for the main facial features and should be considered within the differential diagnosis of TCS.

Deletion of the long arm of chromosome 6: report on a new case with intractable epilepsy

Interstitial deletions in the terminal region of chromosome 6 are rare. The deletion most often occurs de novo. Mental retardation is always described. The most characteristic manifestations are microcephaly, micrognathia, hypotonia, typical facial appearance, strabismus, and congenital heart defects. Although this chromosomal syndrome does not appear to have a distinctive phenotype, epileptic seizures are uncommon in affected individuals. We report on a novel finding in a patient with the 46 XX karyotype and del(6)(q25-q26) who developed intractable epilepsy.

Chromosome 6q deletion: Report of a new case and review of the literature

The authors report an additional case of partial monosomy of the long arm of chromosome 6 [46,XY,del (6)(q22 <font SIZE="3" face="Symbol">®</font> qter)]. Our patient has a large segment beyond 6q25 deleted, then severe psychomotor retardation is expected to occur.

Deletion of the long arm of chromosome 6: two new patients and literature review

Two children with a partial monosomy 6q are reported: a girl with an interstitial deletion [46,XX,del(6)(q16.2q23.1)], and a boy with a terminal deletion [46,XY,del(6)(q25.1)]. Both children presented with developmental delay, facial dysmorphism and a cardiac defect. The patients have been studied using G banding and cosmid probes specific for the long arm of chromosome 6. Clinical data are compared with patients reported in the literature.

Interstitial 6q deletion and Prader-Willi-like phenotype

A third case of an interstitial deletion of the long arm of chromosome 6 with clinical features mimicking Prader-Willi syndrome (PWS) is presented. Although preliminary clinical evaluation in each case suggested PWS, further review revealed that the features in all three cases are not completely compatible with the characteristic findings in Prader-Willi syndrome. Furthermore, the deletions in the three cases do not show a consistent region of overlap. Consequently, no particular band or region in 6q can be defined as associated with obesity. However, our findings confirm the suggestion of Villa et al. in 1995, that individuals with a PWS phenotype who are cytogenetically and molecularly negative for a deletion of 15q11-q13 should be examined for a deletion of 6q.

Interstitial deletion (6)q13q15

We report on a 2-year-old child with psychomotor retardation, facial and urogenital anomalies. His chromosome constitution was 46,XY, del(6)(q13q15). This case further contributes to the karyotype-phenotype correlation of proximal deletion 6q syndromes.

Monosomy 6q1: syndrome delineation

We report on a girl with a de novo 6q1 interstitial deletion. To our knowledge, this is the second reported case with a deletion of 6q11-q15. We review the phenotype of monosomy 6q1. Our patient has manifestations similar to others with monosomy 6q1 including mental deficiency, growth retardation, short neck, and minor facial anomalies.

Mapping of the serotonin 5-HT1D beta autoreceptor gene on chromosome 6 and direct analysis for sequence variants

Abnormal brain serotonin function may be characteristic of several neuropsychiatric disorders. Thus, it is important to identify polymorphic genes and screen for functional variants at loci coding for genes that control normal serotonin functions. 5-HT1D beta is a terminal serotonin autoreceptor which may play a role in regulating serotonin synthesis and release. Using an SSCP technique we screened for 5-HT1D beta coding sequence variants in psychiatrically interviewed populations, which included controls, alcoholics, and alcoholic arsonists and alcoholic violent offenders with low CSF concentrations of the main serotonin metabolite 5-HIAA. A common polymorphism was identified in the 5-HT1D beta gene with allele frequencies of 0.72 and 0.28. The SSCP variant was caused by a silent G to C substitution at nucleotide 861 of the coding region. This polymorphism could also be detected as a HincII RFLP of amplified DNA. DNAs from informative CEPH families were typed for the HincII RFLP and analyzed with respect to 20 linked markers on chromosome 6. Multipoint analysis placed the 5-HT1D beta receptor gene between markers D6S286 and D6S275. A maximum two-point lod score of 10.90 was obtained to D6S26, which had been previously localized on 6q14-15. Chromosomal aberrations involving this region have been previously shown to cause retinal anomalies, developmental delay, and abnormal brain development. This region also contains the gene for North Carolina-type macular dystrophy.

De novo interstitial deletion q16.2q21 on chromosome 6

A de novo interstitial deletion of 6q16.2q21 was observed in a 23-month-old boy with mental and psychomotor delay, obese appearance, minor craniofacial anomalies, and brain anomalies. We compare clinical manifestations of this patient with those observed in previously reported cases with similar 6q interstitial deletions. It is interesting to note the clinical similarities between some patients with interstitial deletions of 6q16 or q21 bands and patients with Prader-Willi syndrome (PWS) and it may help to keep in mind cytogenetic studies of patients with some PWS findings.

The putative melanoma tumor-suppressor gene on human chromosome 6q

The tumorigenicity of malignant melanoma cells may be suppressed experimentally by the introduction into these cells of human chromosome 6 or mouse chromosome 4. These chromosomes share a homologous region, contained in human chromosome 6q12-21. Abnormalities of this human chromosomal region have been found frequently not only in cutaneous and uveal malignant melanomas, but also in a range of other tumors. In all these, mutations of tumor-suppressor genes on human chromosome 6q may be involved. Identification of this putative tumor-suppressor gene may give new insights into the biology of malignant melanomas, and could pave the way for new treatment for such tumors, based upon the tumor-suppressor protein which this gene is likely to encode.

Monosomy 6q: report on four new cases

We report on four patients with partial monosomy of the long arm of chromosome 6: two children presenting with an interstitial deletion del(6)(q14q16), the two others presenting with a terminal deletion del(6)(q25qter). These patients are compared with previous reports in the literature: 16 cases of terminal deletion and 17 cases of interstitial deletion. The deletions most often occur de novo. Mental retardation is always described. Dysmorphic facial features range between minor and major. There may be associated visceral abnormalities. After comparing the size and the localisation of the deletions with clinical data, we are now able to suggest a clinical localisation on chromosome 6.

Ocular albinism in a male with del (6)(q13-q15): candidate region for autosomal recessive ocular albinism?

We describe a boy with an interstitial deletion of 6(q13-q15) and include "coarse" facial features, upslanting palpebral fissures, thin vermilion border of the upper lip, elongated philtrum, developmental delay, and profound hypotonia. The child's eye findings, pedigree, paucity of maternal ocular changes, and lack of melanin macroglobules in the skin suggest that this individual's phenotype is clinically similar to that of autosomal recessive ocular albinism. Though it is possible that this deletion and his ophthalmic disorder are coincidental, we postulate that the ocular albinism may be due to hemizygosity for a paternally derived ocular albinism gene located on chromosome 6 in the region q13-q15. This patient's deletion is secondary to a recombination of a maternal intrachromosomal inverted insertion of this region. Of the 7 reported 6q1 deletions, this is the only case that is due to a familial chromosome rearrangement.

Interstitial deletion of the long arm of chromosome 6 associated with absent pulmonary valve

We report on a newborn infant with a deletion of 6q and absent pulmonary valve. His chromosome constitution was 46,XY,del (6) (q15q21). To our knowledge this is the first case with such combination. Some of his clinical features were found in common in 2 previous 6q- cases with the same breakpoints.

Autopsy findings in interstitial deletion 6q

Autopsy findings from a child with interstitial deletion 6q [46,XX,del(6)(q13q21)] are reported. There was cervical scoliosis, an endocardial cushion defect, right ventricular hypertrophy, subependymal cysts, multicystic kidneys (Potter type IIB), and lung hypoplasia.