Search

Point mutations and genomic deletions of the CDKL5 (STK9) gene on chromosome Xp22 have been reported in patients with severe neurodevelopmental abnormalities, including Rett-like disorders. To date, only larger-sized (8-21 Mb) duplications harboring CDKL5 have been described. We report seven females and four males from seven unrelated families with CDKL5 duplications 540-935 kb in size. Three families of different ethnicities had identical 667kb duplications containing only the shorter CDKL5 isoform. Four affected boys, 8-14 years of age, and three affected girls, 6-8 years of age, manifested autistic behavior, developmental delay, language impairment, and hyperactivity. Of note, two boys and one girl had macrocephaly. Two carrier mothers of the affected boys reported a history of problems with learning and mathematics while at school. None of the patients had epilepsy. Similarly to CDKL5 mutations and deletions, the X-inactivation pattern in all six studied females was random. We hypothesize that the increased dosage of CDKL5 might have affected interactions of this kinase with its substrates, leading to perturbation of synaptic plasticity and learning, and resulting in autistic behavior, developmental and speech delay, hyperactivity, and macrocephaly.

Objective To describe the early detection of two tumors in two children by recognition of unusual features in initial thyroid assessments. Methods We present the clinical findings and results of laboratory studies in two children. In addition, we describe RET proto-oncogene studies in one of them. Results A 14.5-year-old boy was referred for assessment because of short stature in conjunction with lack of physical growth and development. His physical examination was remarkable for height at the 50th percentile (height age, 11.5 years), weight at the 50th percentile (weight age, 13 years), and prepubertal male status. Pertinent laboratory findings were a normal thyroid-stimulating hormone (TSH) level but low free thyroxine (FT4) index. These findings prompted an immediate magnetic resonance imaging study of the head. A parasellar tumor was detected and removed; histopathologic examination revealed that it was a craniopharyngioma. The patient requires lifelong multihormonal therapy for his panhypopituitarism and has responded with physical growth. Our second patient, a 7.5-year-old girl, was referred because of a painless left thyroid nodule of 4 months’ duration. Her physical examination was remarkable for (1) upper lip swelling, (2) intermittent rash, and (3) a goiter with painless mobile left and right nodules. Normal levels of TSH and FT4, serum calcitonin of 6,192 pg/mL, and a fine-needle biopsy specimen that stained strongly for calcitonin were obtained at her first clinic visit. A total thyroidectomy was performed and confirmed the presence of medullary thyroid carcinoma. Genetic studies showed that she was positive for the RET multiple endocrine neoplasia IIB mutation. After 4 years of follow-up, the patient had serum calcitonin levels that remained low ( Conclusion Attention to thyroid physical findings and laboratory studies can promptly lead to correct diagnoses and management of some rare and life-threatening tumors in children. (Endocr Pract. 2001;7:467-473)

In clinical diagnostics, both array comparative genomic hybridization (array CGH) and single nucleotide polymorphism (SNP) genotyping have proven to be powerful genomic technologies utilized for the evaluation of developmental delay, multiple congenital anomalies, and neuropsychiatric disorders. Differences in the ability to resolve genomic changes between these arrays may constitute an implementation challenge for clinicians: which platform (SNP vs array CGH) might best detect the underlying genetic cause for the disease in the patient? While only SNP arrays enable the detection of copy number neutral regions of absence of heterozygosity (AOH), they have limited ability to detect single-exon copy number variants (CNVs) due to the distribution of SNPs across the genome. To provide comprehensive clinical testing for both CNVs and copy-neutral AOH, we enhanced our custom-designed high-resolution oligonucleotide array that has exon-targeted coverage of 1860 genes with 60 000 SNP probes, referred to as Chromosomal Microarray Analysis – Comprehensive (CMA-COMP). Of the 3240 cases evaluated by this array, clinically significant CNVs were detected in 445 cases including 21 cases with exonic events. In addition, 162 cases (5.0%) showed at least one AOH region >10 Mb. We demonstrate that even though this array has a lower density of SNP probes than other commercially available SNP arrays, it reliably detected AOH events >10 Mb as well as exonic CNVs beyond the detection limitations of SNP genotyping. Thus, combining SNP probes and exon-targeted array CGH into one platform provides clinically useful genetic screening in an efficient manner.

Failure-to-thrive (FTT) has been described in patients with organic acidemias treated with low protein diets.To determine if patients with methylmalonic (MMA) or propionic acidemia (PA) can achieve normal growth and nutrition status.A 6-month multicenter outpatient study was conducted with infants and toddlers treated with Propimex-1 Amino Acid-Modified Medical Food With Iron (Ross Products Division, Abbott Laboratories, Columbus, OH). Main outcome measures were anthropometrics, protein status indices, plasma retinol, and alpha-tocopherol.Sixteen patients completed the study. Mean baseline age was 0.54 +/- 0.02 years (range 0.03-3.00 years). By study end, mean National Center for Health Statistics (NCHS) weight centile increased from 26 to 49%; mean crown-heel length centile from 25 to 33%; and mean head circumference centile from 43 to 54%. Mean (+/- SE) protein and energy intakes by6-month-old, 612-month-old, and 14-year-old patients were 15.3 +/- 0.9 g and 645 +/- 10 kcal; 18.3 +/- 1.1 g and 741 +/- 92 kcal; and 25.1 +/- 2.46 g and 1062 +/- 100 kcal, respectively. Plasma glycine concentrations were significantly and negatively correlated with energy intake (r=-0.77, p0.0005). No correlation was found between dietary protein intakes and plasma ammonia concentrations. Protein status indices, retinol and alpha-tocopherol concentrations were within reference ranges at study end.Propimex-1 improved growth and nutrition status in patients with MMA or PA in just 6 months when fed in sufficient amounts. Providing energy and protein for patients with FTT at intakes recommended for catch-up growth may have resulted in even better growth.

We report on a family with fra(10)(q25) ascertained through a female with multiple minor anomalies and present in her phenotypically normal father and other family members. The site is expressed spontaneously at levels of 9% in lymphocytes, 2% in lymphoblasts, and 6% in skin fibroblasts. Expression frequency is significantly enhanced to levels as high as 100% by addition of BrdU to the culture medium. The consistently high level of induced expression in lymphoblasts from the proband facilitates analysis of the biochemical and structural bases of fragile site expression.

The nucleotide sequence for human argininosuccinate synthetase cDNA was determined by analysis of six clones isolated from a single experiment. The sequence covered 1623 nucleotides including 76 bases of poly(A) and contained a 1236 nucleotide open reading frame encoding a protein of 46,434 daltons. In one cDNA isolate, a cloning artifact or perhaps RNA polymerase error involving addition of an A in a region of six A's within the coding sequence was documented. Single base variations in the 3' untranslated region were examined in detail since detection of DNA polymorphisms in the cDNAs could imply over-expression of both alleles at the active locus in canavanine-resistant cells, i.e. a trans-acting mechanism for enzyme overproduction. However, the sequence from five cDNAs suggested some single base artifacts, and DNA polymorphism remains uncertain. The occurrence of three tandem arginine codons in the 5' untranslated region of the cDNA suggested the possibility of an interaction of arginyl-tRNA with mRNA to regulate RNA processing or half-life as a mechanism for arginine-mediated repression.