An autosome complement consists of 29 pairs of single-armed (acrocentric
) chromosomes that gradually decrease in size (NN 1-29).
Carriers of translocations of relatively small chromosomal regions onto an acrocentric
short arm may have a very high risk of having unbalanced offspring (3, 4).
chromosomes are the main origin of sSMCs and chromosome 15 is the most frequent origin of de novo cases that contains 50% of acrocentric
 This raises the prospect of determining the familial transmission of individual acrocentric
Karyotypically, however, Nannospalax has both low diploid (2n) and fundamental (NF) numbers and acrocentric
chromosomes, while Spalax, on the contrary, has high 2n and NF and no acrocentric
chromosomes (Topachevskii, 1969; Lyapunova et al., 1974; Savic and Soldatovic, 1984; Savic and Nevo, 1990; Zima and Kral, 1984; Coskun et al., 2012a, b; Arslan et al., 2016).
Fifteen pairs of acrocentric
chromosomes gradually decreased in size; the sex chromosome (X) was the largest element in the karyotype (Fig.
One of the structural chromosomopathies is the Robertsonian translocation, defined as the fusion of two non-homologous acrocentric
The chromosomal pairs were organized based on heterochromatn locaton (Imai 1991), into: Metacentric (M), Metacentric with pericentromeric and telomeric C-bands ([M.sup.t]), Acrocentric
(A), and Pseudoacrocentric ([A.sup.M]).
A = acrocentric
, M = metacentric, and NOR = Nuclear Organiser Region.
Robertsonian translocations (ROBs) are whole arm rearrangements involving the acrocentric
13-15 and 21-22 chromosomes and carriers are at increased risk for aneuploidy and thus uniparental disomy (UPD).
Jumping translocations of 1q fusing with the short-arm telomeric regions of at least one of the acrocentric
chromosomes 13, 14, 15, 21, and 22 were noted in 75% (25/33) of cases.
Abdel-Basset & Fayza (2004) studied karyotype characteristics, such as chromosome size and variable morphology, including metacentric, submetacentric, and acrocentric
chromosomes, and reported chromosome length ranging from 1.90 to 0.46 [micro]m in Venus verrucosa and 1.10 to 0.50 [micro]m in Ruditapes decussatus, both from the family Veneridae.