(a) What is meant by karyotype? How does its analysis help in diagnosis of the chromosomal aberrations in man? 20 marks (b)…

(a) Karyotype and the Diagnosis of Chromosomal Aberrations Karyotype: the chromosome complement of a species or an individual, described by the number, size, centromere position and banding pattern of its chromosomes. It is shown as a photograph or ideogram in which homologous chromosomes are paired and arranged in decreasing order of size. The normal human karyotype has 46 chromosomes: 22 pairs of autosomes and one pair of sex chromosomes (46,XX in females, 46,XY in males). Under the Denver (1960) system they fall into groups A–G by size and centromere position:

• A (1–3): large metacentric and submetacentric.
• B (4–5): large submetacentric.
• C (6–12 and X): medium submetacentric.
• D (13–15): medium acrocentric.
• E (16–18): small metacentric and submetacentric.
• F (19–20): small metacentric.
• G (21–22 and Y): small acrocentric.

Preparing a karyotype: peripheral blood lymphocytes are cultured for about 72 hours with phytohaemagglutinin (a mitogen). Colchicine arrests dividing cells at metaphase, when chromosomes are most condensed; hypotonic KCl swells the cells; and the cells are fixed in methanol–acetic acid (3:1) and dropped onto slides. Staining follows: G-banding (trypsin and Giemsa) is standard and gives about 400–550 light and dark bands per haploid set, while Q-banding (quinacrine fluorescence), R-banding and C-banding (centromeric heterochromatin) are used for special purposes. Chromosomes are counted, paired and described in ISCN notation. For prenatal diagnosis, amniotic fluid cells (amniocentesis, about 15–18 weeks) or chorionic villi (CVS, about 10–13 weeks) are cultured.

How analysis helps diagnosis

• Numerical aberrations (aneuploidy, from non-disjunction) are found by counting. Examples are Down syndrome (47,XX,+21 or 47,XY,+21), Edwards syndrome (+18), Patau syndrome (+13), Turner syndrome (45,X), Klinefelter syndrome (47,XXY) and XYY. Polyploidy (69,XXX, triploidy) is seen in miscarriages.
• Structural aberrations are found from altered banding. Examples are deletions (cri-du-chat syndrome, 46,XX,del(5p)), duplications, inversions, ring chromosomes and translocations. A Robertsonian translocation (for example 14;21) causes about 4% of Down syndrome and can recur in families. The Philadelphia chromosome, t(9;22)(q34;q11), creates the BCR-ABL fusion gene of chronic myeloid leukaemia.
• Mosaicism: two cell lines (for example 46,XX/47,XX,+21) explain milder cases.
• Clinical uses: diagnosis of dysmorphic or developmentally delayed children, ambiguous genitalia, infertility and repeated miscarriage (where a parent may carry a balanced translocation), prenatal diagnosis for older mothers or abnormal screening, and cancer cytogenetics. This allows genetic counselling on recurrence risk.
• Limits: conventional karyotyping cannot detect changes smaller than about 5–10 megabases, so FISH and chromosomal microarray are used for microdeletions (for example 22q11.2 deletion).

(b) Urbanisation and its Impact on the Family in India Urbanisation is the process by which a growing proportion of a population lives in towns and cities, through natural growth, rural–urban migration and reclassification, together with the spread of an urban way of life: occupational specialisation, individualism, secondary relationships and a money economy (Louis Wirth's "urbanism as a way of life"). India was 31.1% urban in 2011, with megacities such as Mumbai, Delhi, Kolkata, Bengaluru and Chennai.

Impact on the family

• Household structure: migration for jobs, small urban dwellings, rent and transfers split large co-resident households, so nuclear households dominate in cities. Studies show, however, that the change is less than it appears. I.P. Desai (Mahuva, Gujarat) and M.S. Gore (Urbanization and Family Change, 1968, among Aggarwals of Delhi) found that joint-family obligations, visits, remittances and decision-making persisted among separately living kin. A.M. Shah distinguished the household from the family, and Milton Singer showed that Madras industrialists adapted the joint family to business needs.
• Functions: schools, hospitals, markets and the state take over educational, economic and protective functions, while emotional support and socialisation remain with the family.
• Marriage: the age at marriage has risen; more marriages are self-chosen, inter-caste or arranged through matrimonial websites, although caste endogamy remains strong. Dowry has often grown with consumerism, and divorce and live-in relationships are more visible.
• Gender roles: women's education and employment, and dual-earner couples, have raised women's say in decisions, but the "double burden" of paid work and domestic work persists. Where men migrate alone, left-behind women head rural households.
• Elderly and children: smaller households and migration of children create problems of elderly care, loneliness and old-age homes, while crèches and domestic workers replace kin for childcare.
• Urban poor: in slums and migrant settlements, families use kin and caste networks for housing and jobs (chain migration), and household forms fluctuate as members move between village and city.
• New forms: single-person, single-parent and working-women's hostel households are increasing. Overall, urbanisation has changed the form of the Indian family more than its values; the family adapts, as Singer and Gore showed, rather than simply disintegrating.

(c) Contemporary Challenges in Anthropological Fieldwork Malinowski's model of long-term participant observation in a bounded village faces new challenges:

• Ethics and consent: informed consent from communities with low literacy, protecting identities and avoiding harm are now required by the American Anthropological Association's principles, ICMR's National Ethical Guidelines (2017) and institutional ethics committees. Controversies such as Darkness in El Dorado (2000), over research among the Yanomami, and the US Army's Human Terrain System (from 2007), which embedded anthropologists with troops, show the risks.
• Access and security: fieldwork in conflict zones such as parts of the North-East, Kashmir and Maoist-affected central India, and access to protected groups such as the Jarawa and Sentinelese (restricted under the Andaman and Nicobar Protection of Aboriginal Tribes Regulation, 1956), raise safety and permission problems.
• Positionality and representation: after Writing Culture (Clifford and Marcus, 1986), the authority of the ethnographer is questioned. Reflexivity about caste, gender, class and nationality is expected, and native anthropologists, as M.N. Srinivas discussed, face their own insider problems.
• Decolonisation and community rights: communities increasingly demand a share in research design, benefits and data, rejecting extractive or "parachute" research; indigenous data sovereignty is expressed in the CARE principles.
• Changing field sites: mobile, networked and globalised communities require multi-sited ethnography (George Marcus) and "studying up" into bureaucracies, corporations and laboratories (Laura Nader), where access is hard.
• Digital fieldwork: online communities, social media and remote interviews (widespread after COVID-19) raise questions of consent, privacy, authenticity and data security.
• Institutional constraints: short funding cycles, pressure to publish, and preference for quick surveys reduce long-term fieldwork, while restrictions on foreign researchers limit international collaboration. These challenges have made anthropology more ethical, collaborative and reflexive, while keeping fieldwork at the core of the discipline.