The assessment of skeletal status in young patients with Turner syndrome by 2 densitometric techniques: Phalangeal quantitative ultrasound and dual energy X-ray absorptiometry.

BACKGROUND: Studies using dual energy X-ray absorptiometry (DXA) demonstrate a reduction in bone mineral density (BMD) in children and adolescents with Turner syndrome (TS). However, these studies do not take into account changes in bone size, which influence BMD in the case of short-statured patients. Phalangeal quantitative ultrasound (phQUS) measurements have shown an ability to reveal changes due to skeletal growth, aging, and bone and mineral disorders. There is limited data on bone mineral status in girls with TS assessed by 2 different techniques, i.e., DXA and phQUS. OBJECTIVES: The aim of this study was to investigate the potential negative impact of TS on bone status and to assess whether densitometric values were related to former fractures. MATERIAL AND METHODS: In 43 TS girls aged 5-18 years, we evaluated bone status by 2 different densitometric techniques, DXA and phQUS. RESULTS: The mean lumbar spine areal bone mineral density (LS aBMD) Z-score was significantly lower than 0 (the hypothetical mean) compared to the reference population (p < 0.001). The mean LS aBMD height-adjusted Z-score did not differ significantly from 0. The amplitude-dependent speed of sound (Ad-SoS) Z-score was significantly lower than 0 compared with a Polish reference population. There were no significant differences between fractured and fracture-free patients as regards Ad-SoS Z-score and LS aBMD height-adjusted Z-score. CONCLUSIONS: Girls with TS have normal bone density adjusted for height, but significantly decreased phQUS values. Neither DXA nor phalangeal Ad-SoS can identify young TS patients with former fractures.

Genomic findings in patients with clinical suspicion of 22q11.2 deletion syndrome.

Chromosome 22q11.2 deletion syndrome, one of the most common human genomic syndromes, has highly heterogeneous clinical presentation. Patients usually harbor a 1.5 to 3 Mb hemizygous deletion at chromosome 22q11.2, resulting in pathognomic TBX1, CRKL and/or MAPK1 haploinsufficiency. However, there are some individuals with clinical features resembling the syndrome who are eventually diagnosed with genomic disorders affecting other chromosomal regions. The objective of this study was to evaluate the additive value of high-resolution array-CGH testing in the cohort of 41 patients with clinical features of 22q11.2 deletion syndrome and negative results of standard cytogenetic diagnostic testing (karyotype and FISH for 22q11.2 locus). Array-CGH analysis revealed no aberrations at chromosomes 22 or 10 allegedly related to the syndrome. Five (12.2 %) patients were found to have other genomic imbalances, namely 17q21.31 microdeletion syndrome (MIM#610443), 1p36 deletion syndrome (MIM#607872), NF1 microduplication syndrome (MIM#613675), chromosome 6pter-p24 deletion syndrome (MIM#612582) and a novel interstitial deletion at 3q26.31 of 0.65 Mb encompassing a dosage-dependent gene NAALADL2. Our study demonstrates that the implementation of array-CGH into the panel of classic diagnostic procedures adds significantly to their efficacy. It allows for detection of constitutional genomic imbalances in 12 % of subjects with negative result of karyotype and FISH targeted for 22q11.2 region. Moreover, if used as first-tier genetic test, the method would provide immediate diagnosis in ∼40 % phenotypic 22q11.2 deletion subjects.

Novel COL4A1 mutation in an infant with severe dysmorphic syndrome with schizencephaly, periventricular calcifications, and cataract resembling congenital infection.

BACKGROUND: A clinical case is described of growth retardation, severe developmental delay, facial dysmorphic features with microcephaly, as well as congenital cataract, schizencephaly, periventricular calcifications, and epilepsy. METHODS: TORCH infection was suspected, but all tests for toxoplasmosis, rubella, cytomegalovirus, and herpes simplex virus were negative for the child and her mother; however, an increased level of antibodies against parvovirus B19 was detected in the proband. RESULTS: Chromosomal analysis and array-CGH showed no aberration. Target capture sequencing for COL4A1 and COL4A2 revealed a de novo COL4A1 mutation (c.2123G>T [p.Gly708Val]). The mutation occurred at a highly conserved Gly residue in the Gly-X-Y repeat of the collagen triple helical domain, suggesting that these mutations may alter the collagen IV α1α1α2 heterotrimers. The mutation was predicted to be damaging. CONCLUSION: We suggest that COL4A1 testing should be considered in patients with schizencephaly as well as with phenotype suggesting TORCH infection without any proven etiological factors.